Merge branch 'master' into docking # Conflicts: # backends/imgui_impl_sdl2.cpp # backends/imgui_impl_sdl3.cpp # imgui.h # imgui_demo.cpp # imgui_internal.h

diff --git a/backends/imgui_impl_allegro5.cpp b/backends/imgui_impl_allegro5.cpp
index 6ee88a1..29951b9 100644
--- a/backends/imgui_impl_allegro5.cpp
+++ b/backends/imgui_impl_allegro5.cpp

@@ -10,6 +10,7 @@
 // Missing features or Issues:
 //  [ ] Renderer: The renderer is suboptimal as we need to unindex our buffers and convert vertices manually.
 //  [ ] Platform: Missing gamepad support.
+//  [ ] Renderer: Multi-viewport support (multiple windows).
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_allegro5.h b/backends/imgui_impl_allegro5.h
index 135c4ff..e1f3173 100644
--- a/backends/imgui_impl_allegro5.h
+++ b/backends/imgui_impl_allegro5.h

@@ -10,6 +10,7 @@
 // Missing features or Issues:
 //  [ ] Renderer: The renderer is suboptimal as we need to unindex our buffers and convert vertices manually.
 //  [ ] Platform: Missing gamepad support.
+//  [ ] Renderer: Multi-viewport support (multiple windows).
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_android.cpp b/backends/imgui_impl_android.cpp
index a76de1c..13294cb 100644
--- a/backends/imgui_impl_android.cpp
+++ b/backends/imgui_impl_android.cpp

@@ -8,6 +8,7 @@
 //  [ ] Platform: Clipboard support.
 //  [ ] Platform: Gamepad support.
 //  [ ] Platform: Mouse cursor shape and visibility (ImGuiBackendFlags_HasMouseCursors). Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'. FIXME: Check if this is even possible with Android.
+//  [ ] Platform: Multi-viewport support (multiple windows). Not meaningful on Android.
 // Important:
 //  - Consider using SDL or GLFW backend on Android, which will be more full-featured than this.
 //  - FIXME: On-screen keyboard currently needs to be enabled by the application (see examples/ and issue #3446)

diff --git a/backends/imgui_impl_android.h b/backends/imgui_impl_android.h
index f6e4103..308daa2 100644
--- a/backends/imgui_impl_android.h
+++ b/backends/imgui_impl_android.h

@@ -8,6 +8,7 @@
 //  [ ] Platform: Clipboard support.
 //  [ ] Platform: Gamepad support.
 //  [ ] Platform: Mouse cursor shape and visibility (ImGuiBackendFlags_HasMouseCursors). Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'. FIXME: Check if this is even possible with Android.
+//  [ ] Platform: Multi-viewport support (multiple windows). Not meaningful on Android.
 // Important:
 //  - Consider using SDL or GLFW backend on Android, which will be more full-featured than this.
 //  - FIXME: On-screen keyboard currently needs to be enabled by the application (see examples/ and issue #3446)

diff --git a/backends/imgui_impl_dx10.cpp b/backends/imgui_impl_dx10.cpp
index 1187983..b053cb0 100644
--- a/backends/imgui_impl_dx10.cpp
+++ b/backends/imgui_impl_dx10.cpp

@@ -5,6 +5,7 @@
 //  [X] Renderer: User texture binding. Use 'ID3D10ShaderResourceView*' as texture identifier. Read the FAQ about ImTextureID/ImTextureRef!
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -16,6 +17,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2026-01-19: DirectX11: Added 'SamplerNearest' in ImGui_ImplDX11_RenderState. Renamed 'SamplerDefault' to 'SamplerLinear'. 
 //  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-11: DirectX10: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas.
@@ -98,6 +100,10 @@
     return ImGui::GetCurrentContext() ? (ImGui_ImplDX10_Data*)ImGui::GetIO().BackendRendererUserData : nullptr;
 }
 
+// Forward Declarations
+static void ImGui_ImplDX10_InitMultiViewportSupport();
+static void ImGui_ImplDX10_ShutdownMultiViewportSupport();
+
 // Functions
 static void ImGui_ImplDX10_SetupRenderState(ImDrawData* draw_data, ID3D10Device* device)
 {
@@ -610,6 +616,7 @@
     io.BackendRendererName = "imgui_impl_dx10";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
     io.BackendFlags |= ImGuiBackendFlags_RendererHasTextures;   // We can honor ImGuiPlatformIO::Textures[] requests during render.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)
 
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
     platform_io.Renderer_TextureMaxWidth = platform_io.Renderer_TextureMaxHeight = D3D10_REQ_TEXTURE2D_U_OR_V_DIMENSION;
@@ -629,6 +636,8 @@
     if (pDXGIAdapter) pDXGIAdapter->Release();
     bd->pd3dDevice->AddRef();
 
+    ImGui_ImplDX10_InitMultiViewportSupport();
+
     return true;
 }
 
@@ -639,13 +648,14 @@
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
+    ImGui_ImplDX10_ShutdownMultiViewportSupport();
     ImGui_ImplDX10_InvalidateDeviceObjects();
     if (bd->pFactory) { bd->pFactory->Release(); }
     if (bd->pd3dDevice) { bd->pd3dDevice->Release(); }
 
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures);
+    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
     platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
@@ -660,6 +670,131 @@
             IM_ASSERT(0 && "ImGui_ImplDX10_CreateDeviceObjects() failed!");
 }
 
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* RendererUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGui_ImplDX10_ViewportData
+{
+    IDXGISwapChain*         SwapChain;
+    ID3D10RenderTargetView* RTView;
+
+    ImGui_ImplDX10_ViewportData()   { SwapChain = nullptr; RTView = nullptr; }
+    ~ImGui_ImplDX10_ViewportData()  { IM_ASSERT(SwapChain == nullptr && RTView == nullptr); }
+};
+
+static void ImGui_ImplDX10_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplDX10_Data* bd = ImGui_ImplDX10_GetBackendData();
+    ImGui_ImplDX10_ViewportData* vd = IM_NEW(ImGui_ImplDX10_ViewportData)();
+    viewport->RendererUserData = vd;
+
+    // PlatformHandleRaw should always be a HWND, whereas PlatformHandle might be a higher-level handle (e.g. GLFWWindow*, SDL's WindowID).
+    // Some backends will leave PlatformHandleRaw == 0, in which case we assume PlatformHandle will contain the HWND.
+    HWND hwnd = viewport->PlatformHandleRaw ? (HWND)viewport->PlatformHandleRaw : (HWND)viewport->PlatformHandle;
+    IM_ASSERT(hwnd != 0);
+
+    // Create swap chain
+    DXGI_SWAP_CHAIN_DESC sd;
+    ZeroMemory(&sd, sizeof(sd));
+    sd.BufferDesc.Width = (UINT)viewport->Size.x;
+    sd.BufferDesc.Height = (UINT)viewport->Size.y;
+    sd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
+    sd.SampleDesc.Count = 1;
+    sd.SampleDesc.Quality = 0;
+    sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
+    sd.BufferCount = 1;
+    sd.OutputWindow = hwnd;
+    sd.Windowed = TRUE;
+    sd.SwapEffect = DXGI_SWAP_EFFECT_DISCARD;
+    sd.Flags = 0;
+
+    IM_ASSERT(vd->SwapChain == nullptr && vd->RTView == nullptr);
+    bd->pFactory->CreateSwapChain(bd->pd3dDevice, &sd, &vd->SwapChain);
+    bd->pFactory->MakeWindowAssociation(hwnd, DXGI_MWA_NO_ALT_ENTER | DXGI_MWA_NO_WINDOW_CHANGES); // Disable e.g. Alt+Enter
+
+    // Create the render target
+    if (vd->SwapChain)
+    {
+        ID3D10Texture2D* pBackBuffer;
+        vd->SwapChain->GetBuffer(0, IID_PPV_ARGS(&pBackBuffer));
+        bd->pd3dDevice->CreateRenderTargetView(pBackBuffer, nullptr, &vd->RTView);
+        pBackBuffer->Release();
+    }
+}
+
+static void ImGui_ImplDX10_DestroyWindow(ImGuiViewport* viewport)
+{
+    // The main viewport (owned by the application) will always have RendererUserData == 0 here since we didn't create the data for it.
+    if (ImGui_ImplDX10_ViewportData* vd = (ImGui_ImplDX10_ViewportData*)viewport->RendererUserData)
+    {
+        if (vd->SwapChain)
+            vd->SwapChain->Release();
+        vd->SwapChain = nullptr;
+        if (vd->RTView)
+            vd->RTView->Release();
+        vd->RTView = nullptr;
+        IM_DELETE(vd);
+    }
+    viewport->RendererUserData = nullptr;
+}
+
+static void ImGui_ImplDX10_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGui_ImplDX10_Data* bd = ImGui_ImplDX10_GetBackendData();
+    ImGui_ImplDX10_ViewportData* vd = (ImGui_ImplDX10_ViewportData*)viewport->RendererUserData;
+    if (vd->RTView)
+    {
+        vd->RTView->Release();
+        vd->RTView = nullptr;
+    }
+    if (vd->SwapChain)
+    {
+        ID3D10Texture2D* pBackBuffer = nullptr;
+        vd->SwapChain->ResizeBuffers(0, (UINT)size.x, (UINT)size.y, DXGI_FORMAT_UNKNOWN, 0);
+        vd->SwapChain->GetBuffer(0, IID_PPV_ARGS(&pBackBuffer));
+        if (pBackBuffer == nullptr) { fprintf(stderr, "ImGui_ImplDX10_SetWindowSize() failed creating buffers.\n"); return; }
+        bd->pd3dDevice->CreateRenderTargetView(pBackBuffer, nullptr, &vd->RTView);
+        pBackBuffer->Release();
+    }
+}
+
+static void ImGui_ImplDX10_RenderViewport(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplDX10_Data* bd = ImGui_ImplDX10_GetBackendData();
+    ImGui_ImplDX10_ViewportData* vd = (ImGui_ImplDX10_ViewportData*)viewport->RendererUserData;
+    ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+    bd->pd3dDevice->OMSetRenderTargets(1, &vd->RTView, nullptr);
+    if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
+        bd->pd3dDevice->ClearRenderTargetView(vd->RTView, (float*)&clear_color);
+    ImGui_ImplDX10_RenderDrawData(viewport->DrawData);
+}
+
+static void ImGui_ImplDX10_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplDX10_ViewportData* vd = (ImGui_ImplDX10_ViewportData*)viewport->RendererUserData;
+    if (vd->SwapChain)
+        vd->SwapChain->Present(0, 0); // Present without vsync
+}
+
+void ImGui_ImplDX10_InitMultiViewportSupport()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_CreateWindow = ImGui_ImplDX10_CreateWindow;
+    platform_io.Renderer_DestroyWindow = ImGui_ImplDX10_DestroyWindow;
+    platform_io.Renderer_SetWindowSize = ImGui_ImplDX10_SetWindowSize;
+    platform_io.Renderer_RenderWindow = ImGui_ImplDX10_RenderViewport;
+    platform_io.Renderer_SwapBuffers = ImGui_ImplDX10_SwapBuffers;
+}
+
+void ImGui_ImplDX10_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
 //-----------------------------------------------------------------------------
 
 #endif // #ifndef IMGUI_DISABLE

diff --git a/backends/imgui_impl_dx10.h b/backends/imgui_impl_dx10.h
index 87945d6..0d61065 100644
--- a/backends/imgui_impl_dx10.h
+++ b/backends/imgui_impl_dx10.h

@@ -5,6 +5,7 @@
 //  [X] Renderer: User texture binding. Use 'ID3D10ShaderResourceView*' as texture identifier. Read the FAQ about ImTextureID/ImTextureRef!
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_dx11.cpp b/backends/imgui_impl_dx11.cpp
index 193127b..36b936e 100644
--- a/backends/imgui_impl_dx11.cpp
+++ b/backends/imgui_impl_dx11.cpp

@@ -6,6 +6,7 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -17,10 +18,12 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2026-01-19: DirectX11: Added 'SamplerNearest' in ImGui_ImplDX11_RenderState. Renamed 'SamplerDefault' to 'SamplerLinear'.
 //  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-11: DirectX11: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas.
 //  2025-05-07: DirectX11: Honor draw_data->FramebufferScale to allow for custom backends and experiment using it (consistently with other renderer backends, even though in normal condition it is not set under Windows).
+//  2025-02-24: [Docking] Added undocumented ImGui_ImplDX11_SetSwapChainDescs() to configure swap chain creation for secondary viewports.
 //  2025-01-06: DirectX11: Expose VertexConstantBuffer in ImGui_ImplDX11_RenderState. Reset projection matrix in ImDrawCallback_ResetRenderState handler.
 //  2024-10-07: DirectX11: Changed default texture sampler to Clamp instead of Repeat/Wrap.
 //  2024-10-07: DirectX11: Expose selected render state in ImGui_ImplDX11_RenderState, which you can access in 'void* platform_io.Renderer_RenderState' during draw callbacks.
@@ -85,6 +88,7 @@
     ID3D11DepthStencilState*    pDepthStencilState;
     int                         VertexBufferSize;
     int                         IndexBufferSize;
+    ImVector<DXGI_SWAP_CHAIN_DESC> SwapChainDescsForViewports;
 
     ImGui_ImplDX11_Data()       { memset((void*)this, 0, sizeof(*this)); VertexBufferSize = 5000; IndexBufferSize = 10000; }
 };
@@ -101,6 +105,10 @@
     return ImGui::GetCurrentContext() ? (ImGui_ImplDX11_Data*)ImGui::GetIO().BackendRendererUserData : nullptr;
 }
 
+// Forward Declarations
+static void ImGui_ImplDX11_InitMultiViewportSupport();
+static void ImGui_ImplDX11_ShutdownMultiViewportSupport();
+
 // Functions
 static void ImGui_ImplDX11_SetupRenderState(const ImDrawData* draw_data, ID3D11DeviceContext* device_ctx)
 {
@@ -626,6 +634,7 @@
     io.BackendRendererName = "imgui_impl_dx11";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
     io.BackendFlags |= ImGuiBackendFlags_RendererHasTextures;   // We can honor ImGuiPlatformIO::Textures[] requests during render.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)
 
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
     platform_io.Renderer_TextureMaxWidth = platform_io.Renderer_TextureMaxHeight = D3D11_REQ_TEXTURE2D_U_OR_V_DIMENSION;
@@ -648,6 +657,8 @@
     bd->pd3dDevice->AddRef();
     bd->pd3dDeviceContext->AddRef();
 
+    ImGui_ImplDX11_InitMultiViewportSupport();
+
     return true;
 }
 
@@ -658,6 +669,7 @@
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
+    ImGui_ImplDX11_ShutdownMultiViewportSupport();
     ImGui_ImplDX11_InvalidateDeviceObjects();
     if (bd->pFactory)             { bd->pFactory->Release(); }
     if (bd->pd3dDevice)           { bd->pd3dDevice->Release(); }
@@ -665,7 +677,7 @@
 
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures);
+    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
     platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
@@ -680,6 +692,152 @@
             IM_ASSERT(0 && "ImGui_ImplDX11_CreateDeviceObjects() failed!");
 }
 
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* RendererUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGui_ImplDX11_ViewportData
+{
+    IDXGISwapChain*                 SwapChain;
+    ID3D11RenderTargetView*         RTView;
+
+    ImGui_ImplDX11_ViewportData()   { SwapChain = nullptr; RTView = nullptr; }
+    ~ImGui_ImplDX11_ViewportData()  { IM_ASSERT(SwapChain == nullptr && RTView == nullptr); }
+};
+
+// Multi-Viewports: configure templates used when creating swapchains for secondary viewports. Will try them in order.
+// This is intentionally not declared in the .h file yet, so you will need to copy this declaration:
+void ImGui_ImplDX11_SetSwapChainDescs(const DXGI_SWAP_CHAIN_DESC* desc_templates, int desc_templates_count);
+void ImGui_ImplDX11_SetSwapChainDescs(const DXGI_SWAP_CHAIN_DESC* desc_templates, int desc_templates_count)
+{
+    ImGui_ImplDX11_Data* bd = ImGui_ImplDX11_GetBackendData();
+    bd->SwapChainDescsForViewports.resize(desc_templates_count);
+    memcpy(bd->SwapChainDescsForViewports.Data, desc_templates, sizeof(DXGI_SWAP_CHAIN_DESC));
+}
+
+static void ImGui_ImplDX11_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplDX11_Data* bd = ImGui_ImplDX11_GetBackendData();
+    ImGui_ImplDX11_ViewportData* vd = IM_NEW(ImGui_ImplDX11_ViewportData)();
+    viewport->RendererUserData = vd;
+
+    // PlatformHandleRaw should always be a HWND, whereas PlatformHandle might be a higher-level handle (e.g. GLFWWindow*, SDL's WindowID).
+    // Some backends will leave PlatformHandleRaw == 0, in which case we assume PlatformHandle will contain the HWND.
+    HWND hwnd = viewport->PlatformHandleRaw ? (HWND)viewport->PlatformHandleRaw : (HWND)viewport->PlatformHandle;
+    IM_ASSERT(hwnd != 0);
+    IM_ASSERT(vd->SwapChain == nullptr && vd->RTView == nullptr);
+
+    // Create swap chain
+    HRESULT hr = DXGI_ERROR_UNSUPPORTED;
+    for (const DXGI_SWAP_CHAIN_DESC& sd_template : bd->SwapChainDescsForViewports)
+    {
+        IM_ASSERT(sd_template.BufferDesc.Width == 0 && sd_template.BufferDesc.Height == 0 && sd_template.OutputWindow == nullptr);
+        DXGI_SWAP_CHAIN_DESC sd = sd_template;
+        sd.BufferDesc.Width = (UINT)viewport->Size.x;
+        sd.BufferDesc.Height = (UINT)viewport->Size.y;
+        sd.OutputWindow = hwnd;
+        hr = bd->pFactory->CreateSwapChain(bd->pd3dDevice, &sd, &vd->SwapChain);
+        if (SUCCEEDED(hr))
+            break;
+    }
+    IM_ASSERT(SUCCEEDED(hr));
+    bd->pFactory->MakeWindowAssociation(hwnd, DXGI_MWA_NO_ALT_ENTER | DXGI_MWA_NO_WINDOW_CHANGES); // Disable e.g. Alt+Enter
+
+    // Create the render target
+    if (vd->SwapChain != nullptr)
+    {
+        ID3D11Texture2D* pBackBuffer;
+        vd->SwapChain->GetBuffer(0, IID_PPV_ARGS(&pBackBuffer));
+        bd->pd3dDevice->CreateRenderTargetView(pBackBuffer, nullptr, &vd->RTView);
+        pBackBuffer->Release();
+    }
+}
+
+static void ImGui_ImplDX11_DestroyWindow(ImGuiViewport* viewport)
+{
+    // The main viewport (owned by the application) will always have RendererUserData == nullptr since we didn't create the data for it.
+    if (ImGui_ImplDX11_ViewportData* vd = (ImGui_ImplDX11_ViewportData*)viewport->RendererUserData)
+    {
+        if (vd->SwapChain)
+            vd->SwapChain->Release();
+        vd->SwapChain = nullptr;
+        if (vd->RTView)
+            vd->RTView->Release();
+        vd->RTView = nullptr;
+        IM_DELETE(vd);
+    }
+    viewport->RendererUserData = nullptr;
+}
+
+static void ImGui_ImplDX11_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGui_ImplDX11_Data* bd = ImGui_ImplDX11_GetBackendData();
+    ImGui_ImplDX11_ViewportData* vd = (ImGui_ImplDX11_ViewportData*)viewport->RendererUserData;
+    if (vd->RTView)
+    {
+        vd->RTView->Release();
+        vd->RTView = nullptr;
+    }
+    if (vd->SwapChain)
+    {
+        ID3D11Texture2D* pBackBuffer = nullptr;
+        vd->SwapChain->ResizeBuffers(0, (UINT)size.x, (UINT)size.y, DXGI_FORMAT_UNKNOWN, 0);
+        vd->SwapChain->GetBuffer(0, IID_PPV_ARGS(&pBackBuffer));
+        if (pBackBuffer == nullptr) { fprintf(stderr, "ImGui_ImplDX11_SetWindowSize() failed creating buffers.\n"); return; }
+        bd->pd3dDevice->CreateRenderTargetView(pBackBuffer, nullptr, &vd->RTView);
+        pBackBuffer->Release();
+    }
+}
+
+static void ImGui_ImplDX11_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplDX11_Data* bd = ImGui_ImplDX11_GetBackendData();
+    ImGui_ImplDX11_ViewportData* vd = (ImGui_ImplDX11_ViewportData*)viewport->RendererUserData;
+    ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+    bd->pd3dDeviceContext->OMSetRenderTargets(1, &vd->RTView, nullptr);
+    if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
+        bd->pd3dDeviceContext->ClearRenderTargetView(vd->RTView, (float*)&clear_color);
+    ImGui_ImplDX11_RenderDrawData(viewport->DrawData);
+}
+
+static void ImGui_ImplDX11_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplDX11_ViewportData* vd = (ImGui_ImplDX11_ViewportData*)viewport->RendererUserData;
+    if (vd->SwapChain)
+        vd->SwapChain->Present(0, 0); // Present without vsync
+}
+
+static void ImGui_ImplDX11_InitMultiViewportSupport()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_CreateWindow = ImGui_ImplDX11_CreateWindow;
+    platform_io.Renderer_DestroyWindow = ImGui_ImplDX11_DestroyWindow;
+    platform_io.Renderer_SetWindowSize = ImGui_ImplDX11_SetWindowSize;
+    platform_io.Renderer_RenderWindow = ImGui_ImplDX11_RenderWindow;
+    platform_io.Renderer_SwapBuffers = ImGui_ImplDX11_SwapBuffers;
+
+    // Default swapchain format
+    DXGI_SWAP_CHAIN_DESC sd;
+    ZeroMemory(&sd, sizeof(sd));
+    sd.BufferDesc.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
+    sd.SampleDesc.Count = 1;
+    sd.SampleDesc.Quality = 0;
+    sd.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
+    sd.BufferCount = 1;
+    sd.Windowed = TRUE;
+    sd.SwapEffect = DXGI_SWAP_EFFECT_DISCARD;
+    sd.Flags = 0;
+    ImGui_ImplDX11_SetSwapChainDescs(&sd, 1);
+}
+
+static void ImGui_ImplDX11_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
 //-----------------------------------------------------------------------------
 
 #endif // #ifndef IMGUI_DISABLE

diff --git a/backends/imgui_impl_dx11.h b/backends/imgui_impl_dx11.h
index 338e009..bf27e42 100644
--- a/backends/imgui_impl_dx11.h
+++ b/backends/imgui_impl_dx11.h

@@ -6,6 +6,7 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_dx12.cpp b/backends/imgui_impl_dx12.cpp
index a542078..976c937 100644
--- a/backends/imgui_impl_dx12.cpp
+++ b/backends/imgui_impl_dx12.cpp

@@ -6,6 +6,8 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
+//      FIXME: The transition from removing a viewport and moving the window in an existing hosted viewport tends to flicker.
 
 // The aim of imgui_impl_dx12.h/.cpp is to be usable in your engine without any modification.
 // IF YOU FEEL YOU NEED TO MAKE ANY CHANGE TO THIS CODE, please share them and your feedback at https://github.com/ocornut/imgui/
@@ -20,6 +22,8 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-10-23: [Docking] DirectX12: Fixed an issue in synchronization logic improving rendering throughput for secondary viewports. (#8961, #9025)
 //  2025-10-11: DirectX12: Reuse texture upload buffer and grow it only when necessary. (#9002)
 //  2025-09-29: DirectX12: Rework synchronization logic. (#8961)
 //  2025-09-29: DirectX12: Enable swapchain tearing to eliminate viewports framerate throttling. (#8965)
@@ -115,9 +119,6 @@
     UINT                        pTexUploadBufferSize;
     void*                       pTexUploadBufferMapped;
 
-    ImGui_ImplDX12_RenderBuffers* pFrameResources;
-    UINT                        frameIndex;
-
     ImGui_ImplDX12_Data()       { memset((void*)this, 0, sizeof(*this)); }
 };
 
@@ -137,11 +138,85 @@
     int                 VertexBufferSize;
 };
 
+// Buffers used for secondary viewports created by the multi-viewports systems
+struct ImGui_ImplDX12_FrameContext
+{
+    UINT64                          FenceValue;
+    ID3D12CommandAllocator*         CommandAllocator;
+    ID3D12Resource*                 RenderTarget;
+    D3D12_CPU_DESCRIPTOR_HANDLE     RenderTargetCpuDescriptors;
+};
+
+// Helper structure we store in the void* RendererUserData field of each ImGuiViewport to easily retrieve our backend data.
+// Main viewport created by application will only use the Resources field.
+// Secondary viewports created by this backend will use all the fields (including Window fields),
+struct ImGui_ImplDX12_ViewportData
+{
+    // Window
+    ID3D12CommandQueue*             CommandQueue;
+    ID3D12GraphicsCommandList*      CommandList;
+    ID3D12DescriptorHeap*           RtvDescHeap;
+    IDXGISwapChain3*                SwapChain;
+    HANDLE                          SwapChainWaitableObject;
+    UINT                            NumFramesInFlight;
+    ImGui_ImplDX12_FrameContext*    FrameCtx;
+
+    // Render buffers
+    UINT                            FrameIndex;
+    ImGui_ImplDX12_RenderBuffers*   FrameRenderBuffers;
+
+    ImGui_ImplDX12_ViewportData(UINT num_frames_in_flight)
+    {
+        CommandQueue = nullptr;
+        CommandList = nullptr;
+        RtvDescHeap = nullptr;
+        SwapChain = nullptr;
+        SwapChainWaitableObject = nullptr;
+        NumFramesInFlight = num_frames_in_flight;
+        FrameCtx = new ImGui_ImplDX12_FrameContext[NumFramesInFlight];
+        FrameIndex = 0;
+        FrameRenderBuffers = new ImGui_ImplDX12_RenderBuffers[NumFramesInFlight];
+
+        for (UINT i = 0; i < NumFramesInFlight; ++i)
+        {
+            FrameCtx[i].FenceValue = 0;
+            FrameCtx[i].CommandAllocator = nullptr;
+            FrameCtx[i].RenderTarget = nullptr;
+
+            // Create buffers with a default size (they will later be grown as needed)
+            FrameRenderBuffers[i].IndexBuffer = nullptr;
+            FrameRenderBuffers[i].VertexBuffer = nullptr;
+            FrameRenderBuffers[i].VertexBufferSize = 5000;
+            FrameRenderBuffers[i].IndexBufferSize = 10000;
+        }
+    }
+    ~ImGui_ImplDX12_ViewportData()
+    {
+        IM_ASSERT(CommandQueue == nullptr && CommandList == nullptr);
+        IM_ASSERT(RtvDescHeap == nullptr);
+        IM_ASSERT(SwapChain == nullptr);
+        IM_ASSERT(SwapChainWaitableObject == nullptr);
+
+        for (UINT i = 0; i < NumFramesInFlight; ++i)
+        {
+            IM_ASSERT(FrameCtx[i].CommandAllocator == nullptr && FrameCtx[i].RenderTarget == nullptr);
+            IM_ASSERT(FrameRenderBuffers[i].IndexBuffer == nullptr && FrameRenderBuffers[i].VertexBuffer == nullptr);
+        }
+
+        delete[] FrameCtx; FrameCtx = nullptr;
+        delete[] FrameRenderBuffers; FrameRenderBuffers = nullptr;
+    }
+};
+
 struct VERTEX_CONSTANT_BUFFER_DX12
 {
     float   mvp[4][4];
 };
 
+// Forward Declarations
+static void ImGui_ImplDX12_InitMultiViewportSupport();
+static void ImGui_ImplDX12_ShutdownMultiViewportSupport();
+
 // FIXME-WIP: Allow user to forward declare those two, for until we come up with a backend agnostic API to do this. (#9173)
 void ImGui_ImplDX12_SetupSamplerLinear(ID3D12GraphicsCommandList* command_list);
 void ImGui_ImplDX12_SetupSamplerNearest(ID3D12GraphicsCommandList* command_list);
@@ -236,8 +311,9 @@
 
     // FIXME: We are assuming that this only gets called once per frame!
     ImGui_ImplDX12_Data* bd = ImGui_ImplDX12_GetBackendData();
-    bd->frameIndex = bd->frameIndex + 1;
-    ImGui_ImplDX12_RenderBuffers* fr = &bd->pFrameResources[bd->frameIndex % bd->numFramesInFlight];
+    ImGui_ImplDX12_ViewportData* vd = (ImGui_ImplDX12_ViewportData*)draw_data->OwnerViewport->RendererUserData;
+    ImGui_ImplDX12_RenderBuffers* fr = &vd->FrameRenderBuffers[vd->FrameIndex % bd->numFramesInFlight];
+    vd->FrameIndex++;
 
     // Create and grow vertex/index buffers if needed
     if (fr->VertexBuffer == nullptr || fr->VertexBufferSize < draw_data->TotalVtxCount)
@@ -839,6 +915,13 @@
     return true;
 }
 
+static void ImGui_ImplDX12_DestroyRenderBuffers(ImGui_ImplDX12_RenderBuffers* render_buffers)
+{
+    SafeRelease(render_buffers->IndexBuffer);
+    SafeRelease(render_buffers->VertexBuffer);
+    render_buffers->IndexBufferSize = render_buffers->VertexBufferSize = 0;
+}
+
 void    ImGui_ImplDX12_InvalidateDeviceObjects()
 {
     ImGui_ImplDX12_Data* bd = ImGui_ImplDX12_GetBackendData();
@@ -871,13 +954,6 @@
     for (ImTextureData* tex : ImGui::GetPlatformIO().Textures)
         if (tex->RefCount == 1)
             ImGui_ImplDX12_DestroyTexture(tex);
-
-    for (UINT i = 0; i < bd->numFramesInFlight; i++)
-    {
-        ImGui_ImplDX12_RenderBuffers* fr = &bd->pFrameResources[i];
-        SafeRelease(fr->IndexBuffer);
-        SafeRelease(fr->VertexBuffer);
-    }
 }
 
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
@@ -926,6 +1002,15 @@
     io.BackendRendererName = "imgui_impl_dx12";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
     io.BackendFlags |= ImGuiBackendFlags_RendererHasTextures;   // We can honor ImGuiPlatformIO::Textures[] requests during render.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)
+
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        ImGui_ImplDX12_InitMultiViewportSupport();
+
+    // Create a dummy ImGui_ImplDX12_ViewportData holder for the main viewport,
+    // Since this is created and managed by the application, we will only use the ->Resources[] fields.
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    main_viewport->RendererUserData = IM_NEW(ImGui_ImplDX12_ViewportData)(bd->numFramesInFlight);
 
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
     if (init_info->SrvDescriptorAllocFn == nullptr)
@@ -933,18 +1018,6 @@
 #endif
     IM_ASSERT(init_info->SrvDescriptorAllocFn != nullptr && init_info->SrvDescriptorFreeFn != nullptr);
 
-    // Create buffers with a default size (they will later be grown as needed)
-    bd->frameIndex = UINT_MAX;
-    bd->pFrameResources = new ImGui_ImplDX12_RenderBuffers[bd->numFramesInFlight];
-    for (int i = 0; i < (int)bd->numFramesInFlight; i++)
-    {
-        ImGui_ImplDX12_RenderBuffers* fr = &bd->pFrameResources[i];
-        fr->IndexBuffer = nullptr;
-        fr->VertexBuffer = nullptr;
-        fr->IndexBufferSize = 10000;
-        fr->VertexBufferSize = 5000;
-    }
-
     return true;
 }
 
@@ -985,12 +1058,23 @@
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
+    // Manually delete main viewport render resources in-case we haven't initialized for viewports
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    if (ImGui_ImplDX12_ViewportData* vd = (ImGui_ImplDX12_ViewportData*)main_viewport->RendererUserData)
+    {
+        // We could just call ImGui_ImplDX12_DestroyWindow(main_viewport) as a convenience but that would be misleading since we only use data->Resources[]
+        for (UINT i = 0; i < bd->numFramesInFlight; i++)
+            ImGui_ImplDX12_DestroyRenderBuffers(&vd->FrameRenderBuffers[i]);
+        IM_DELETE(vd);
+        main_viewport->RendererUserData = nullptr;
+    }
+
+    ImGui_ImplDX12_ShutdownMultiViewportSupport();
     ImGui_ImplDX12_InvalidateDeviceObjects();
-    delete[] bd->pFrameResources;
 
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures);
+    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
     platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
@@ -1005,6 +1089,254 @@
             IM_ASSERT(0 && "ImGui_ImplDX12_CreateDeviceObjects() failed!");
 }
 
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+static void ImGui_ImplDX12_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplDX12_Data* bd = ImGui_ImplDX12_GetBackendData();
+    ImGui_ImplDX12_ViewportData* vd = IM_NEW(ImGui_ImplDX12_ViewportData)(bd->numFramesInFlight);
+    viewport->RendererUserData = vd;
+
+    // PlatformHandleRaw should always be a HWND, whereas PlatformHandle might be a higher-level handle (e.g. GLFWWindow*, SDL's WindowID).
+    // Some backends will leave PlatformHandleRaw == 0, in which case we assume PlatformHandle will contain the HWND.
+    HWND hwnd = viewport->PlatformHandleRaw ? (HWND)viewport->PlatformHandleRaw : (HWND)viewport->PlatformHandle;
+    IM_ASSERT(hwnd != 0);
+
+    // Use shared command queue from init info
+    vd->FrameIndex = 0;
+    vd->CommandQueue = bd->pCommandQueue;
+
+    // Create command allocator.
+    HRESULT res = S_OK;
+    for (UINT i = 0; i < bd->numFramesInFlight; ++i)
+    {
+        res = bd->pd3dDevice->CreateCommandAllocator(D3D12_COMMAND_LIST_TYPE_DIRECT, IID_PPV_ARGS(&vd->FrameCtx[i].CommandAllocator));
+        IM_ASSERT(res == S_OK);
+    }
+
+    // Create command list.
+    res = bd->pd3dDevice->CreateCommandList(0, D3D12_COMMAND_LIST_TYPE_DIRECT, vd->FrameCtx[0].CommandAllocator, nullptr, IID_PPV_ARGS(&vd->CommandList));
+    IM_ASSERT(res == S_OK);
+    vd->CommandList->Close();
+
+    // Create swap chain
+    // FIXME-VIEWPORT: May want to copy/inherit swap chain settings from the user/application.
+    DXGI_SWAP_CHAIN_DESC1 sd1;
+    ZeroMemory(&sd1, sizeof(sd1));
+    sd1.BufferCount = bd->numFramesInFlight;
+    sd1.Width = (UINT)viewport->Size.x;
+    sd1.Height = (UINT)viewport->Size.y;
+    sd1.Format = bd->RTVFormat;
+    sd1.BufferUsage = DXGI_USAGE_RENDER_TARGET_OUTPUT;
+    sd1.SampleDesc.Count = 1;
+    sd1.SampleDesc.Quality = 0;
+    sd1.SwapEffect = DXGI_SWAP_EFFECT_FLIP_DISCARD;
+    sd1.AlphaMode = DXGI_ALPHA_MODE_UNSPECIFIED;
+    sd1.Scaling = DXGI_SCALING_NONE;
+    sd1.Stereo = FALSE;
+    sd1.Flags = DXGI_SWAP_CHAIN_FLAG_FRAME_LATENCY_WAITABLE_OBJECT;
+
+    if (bd->tearingSupport)
+        sd1.Flags |= DXGI_SWAP_CHAIN_FLAG_ALLOW_TEARING;
+
+    IDXGISwapChain1* swap_chain = nullptr;
+    res = bd->pdxgiFactory->CreateSwapChainForHwnd(vd->CommandQueue, hwnd, &sd1, nullptr, nullptr, &swap_chain);
+    IM_ASSERT(res == S_OK);
+    res = bd->pdxgiFactory->MakeWindowAssociation(hwnd, DXGI_MWA_NO_ALT_ENTER | DXGI_MWA_NO_WINDOW_CHANGES); // Disable e.g. Alt+Enter
+    IM_ASSERT(res == S_OK);
+
+    // Or swapChain.As(&mSwapChain)
+    IM_ASSERT(vd->SwapChain == nullptr);
+    swap_chain->QueryInterface(IID_PPV_ARGS(&vd->SwapChain));
+    swap_chain->Release();
+
+    // Create the render targets and waitable object
+    if (vd->SwapChain)
+    {
+        D3D12_DESCRIPTOR_HEAP_DESC desc = {};
+        desc.Type = D3D12_DESCRIPTOR_HEAP_TYPE_RTV;
+        desc.NumDescriptors = bd->numFramesInFlight;
+        desc.Flags = D3D12_DESCRIPTOR_HEAP_FLAG_NONE;
+        desc.NodeMask = 1;
+
+        HRESULT hr = bd->pd3dDevice->CreateDescriptorHeap(&desc, IID_PPV_ARGS(&vd->RtvDescHeap));
+        IM_ASSERT(hr == S_OK);
+
+        SIZE_T rtv_descriptor_size = bd->pd3dDevice->GetDescriptorHandleIncrementSize(D3D12_DESCRIPTOR_HEAP_TYPE_RTV);
+        D3D12_CPU_DESCRIPTOR_HANDLE rtv_handle = vd->RtvDescHeap->GetCPUDescriptorHandleForHeapStart();
+        for (UINT i = 0; i < bd->numFramesInFlight; i++)
+        {
+            vd->FrameCtx[i].RenderTargetCpuDescriptors = rtv_handle;
+            rtv_handle.ptr += rtv_descriptor_size;
+        }
+
+        ID3D12Resource* back_buffer;
+        for (UINT i = 0; i < bd->numFramesInFlight; i++)
+        {
+            IM_ASSERT(vd->FrameCtx[i].RenderTarget == nullptr);
+            vd->SwapChain->GetBuffer(i, IID_PPV_ARGS(&back_buffer));
+            bd->pd3dDevice->CreateRenderTargetView(back_buffer, nullptr, vd->FrameCtx[i].RenderTargetCpuDescriptors);
+            vd->FrameCtx[i].RenderTarget = back_buffer;
+        }
+
+        hr = vd->SwapChain->SetMaximumFrameLatency(bd->numFramesInFlight);
+        IM_ASSERT(hr == S_OK);
+        vd->SwapChainWaitableObject = vd->SwapChain->GetFrameLatencyWaitableObject();
+    }
+
+    for (UINT i = 0; i < bd->numFramesInFlight; i++)
+        ImGui_ImplDX12_DestroyRenderBuffers(&vd->FrameRenderBuffers[i]);
+}
+
+static void ImGui_WaitForPendingOperations(ImGui_ImplDX12_ViewportData* vd)
+{
+    ImGui_ImplDX12_Data* bd = ImGui_ImplDX12_GetBackendData();
+    HRESULT hr = vd->CommandQueue->Signal(bd->Fence, ++bd->FenceLastSignaledValue);
+    IM_ASSERT(hr == S_OK);
+
+    hr = bd->Fence->SetEventOnCompletion(bd->FenceLastSignaledValue, bd->FenceEvent);
+    IM_ASSERT(hr == S_OK);
+    ::WaitForSingleObject(bd->FenceEvent, INFINITE);
+}
+
+static ImGui_ImplDX12_FrameContext* ImGui_WaitForNextFrameContext(ImGui_ImplDX12_ViewportData* vd)
+{
+    ImGui_ImplDX12_Data* bd = ImGui_ImplDX12_GetBackendData();
+    ImGui_ImplDX12_FrameContext* frame_context = &vd->FrameCtx[vd->FrameIndex % vd->NumFramesInFlight];
+    if (bd->Fence->GetCompletedValue() < frame_context->FenceValue)
+    {
+        HRESULT hr = bd->Fence->SetEventOnCompletion(frame_context->FenceValue, bd->FenceEvent);
+        IM_ASSERT(hr == S_OK);
+        HANDLE waitableObjects[] = { vd->SwapChainWaitableObject, bd->FenceEvent };
+        ::WaitForMultipleObjects(2, waitableObjects, TRUE, INFINITE);
+    }
+    else
+    {
+        ::WaitForSingleObject(vd->SwapChainWaitableObject, INFINITE);
+    }
+    return frame_context;
+}
+
+static void ImGui_ImplDX12_DestroyWindow(ImGuiViewport* viewport)
+{
+    // The main viewport (owned by the application) will always have RendererUserData == 0 since we didn't create the data for it.
+    ImGui_ImplDX12_Data* bd = ImGui_ImplDX12_GetBackendData();
+    if (ImGui_ImplDX12_ViewportData* vd = (ImGui_ImplDX12_ViewportData*)viewport->RendererUserData)
+    {
+        ImGui_WaitForPendingOperations(vd);
+
+        vd->CommandQueue = nullptr;
+        ::CloseHandle(vd->SwapChainWaitableObject);
+        vd->SwapChainWaitableObject = nullptr;
+        SafeRelease(vd->CommandList);
+        SafeRelease(vd->SwapChain);
+        SafeRelease(vd->RtvDescHeap);
+
+        for (UINT i = 0; i < bd->numFramesInFlight; i++)
+        {
+            SafeRelease(vd->FrameCtx[i].RenderTarget);
+            SafeRelease(vd->FrameCtx[i].CommandAllocator);
+            ImGui_ImplDX12_DestroyRenderBuffers(&vd->FrameRenderBuffers[i]);
+        }
+        IM_DELETE(vd);
+    }
+    viewport->RendererUserData = nullptr;
+}
+
+static void ImGui_ImplDX12_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGui_ImplDX12_Data* bd = ImGui_ImplDX12_GetBackendData();
+    ImGui_ImplDX12_ViewportData* vd = (ImGui_ImplDX12_ViewportData*)viewport->RendererUserData;
+
+    ImGui_WaitForPendingOperations(vd);
+
+    for (UINT i = 0; i < bd->numFramesInFlight; i++)
+        SafeRelease(vd->FrameCtx[i].RenderTarget);
+
+    if (vd->SwapChain)
+    {
+        ID3D12Resource* back_buffer = nullptr;
+        DXGI_SWAP_CHAIN_DESC1 desc = {};
+        vd->SwapChain->GetDesc1(&desc);
+        vd->SwapChain->ResizeBuffers(0, (UINT)size.x, (UINT)size.y, desc.Format, desc.Flags);
+        for (UINT i = 0; i < bd->numFramesInFlight; i++)
+        {
+            vd->SwapChain->GetBuffer(i, IID_PPV_ARGS(&back_buffer));
+            bd->pd3dDevice->CreateRenderTargetView(back_buffer, nullptr, vd->FrameCtx[i].RenderTargetCpuDescriptors);
+            vd->FrameCtx[i].RenderTarget = back_buffer;
+        }
+    }
+}
+
+static void ImGui_ImplDX12_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplDX12_Data* bd = ImGui_ImplDX12_GetBackendData();
+    ImGui_ImplDX12_ViewportData* vd = (ImGui_ImplDX12_ViewportData*)viewport->RendererUserData;
+
+    ImGui_ImplDX12_FrameContext* frame_context = ImGui_WaitForNextFrameContext(vd);
+    UINT back_buffer_idx = vd->SwapChain->GetCurrentBackBufferIndex();
+
+    const ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+    D3D12_RESOURCE_BARRIER barrier = {};
+    barrier.Type = D3D12_RESOURCE_BARRIER_TYPE_TRANSITION;
+    barrier.Flags = D3D12_RESOURCE_BARRIER_FLAG_NONE;
+    barrier.Transition.pResource = vd->FrameCtx[back_buffer_idx].RenderTarget;
+    barrier.Transition.Subresource = D3D12_RESOURCE_BARRIER_ALL_SUBRESOURCES;
+    barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_PRESENT;
+    barrier.Transition.StateAfter = D3D12_RESOURCE_STATE_RENDER_TARGET;
+
+    // Draw
+    ID3D12GraphicsCommandList* cmd_list = vd->CommandList;
+
+    frame_context->CommandAllocator->Reset();
+    cmd_list->Reset(frame_context->CommandAllocator, nullptr);
+    cmd_list->ResourceBarrier(1, &barrier);
+    cmd_list->OMSetRenderTargets(1, &vd->FrameCtx[back_buffer_idx].RenderTargetCpuDescriptors, FALSE, nullptr);
+    if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
+        cmd_list->ClearRenderTargetView(vd->FrameCtx[back_buffer_idx].RenderTargetCpuDescriptors, (const float*)&clear_color, 0, nullptr);
+    cmd_list->SetDescriptorHeaps(1, &bd->pd3dSrvDescHeap);
+
+    ImGui_ImplDX12_RenderDrawData(viewport->DrawData, cmd_list);
+
+    barrier.Transition.StateBefore = D3D12_RESOURCE_STATE_RENDER_TARGET;
+    barrier.Transition.StateAfter = D3D12_RESOURCE_STATE_PRESENT;
+    cmd_list->ResourceBarrier(1, &barrier);
+    cmd_list->Close();
+
+    vd->CommandQueue->ExecuteCommandLists(1, (ID3D12CommandList* const*)&cmd_list);
+
+    HRESULT hr = vd->CommandQueue->Signal(bd->Fence, ++bd->FenceLastSignaledValue);
+    IM_ASSERT(hr == S_OK);
+    frame_context->FenceValue = bd->FenceLastSignaledValue;
+}
+
+static void ImGui_ImplDX12_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplDX12_Data* bd = ImGui_ImplDX12_GetBackendData();
+    ImGui_ImplDX12_ViewportData* vd = (ImGui_ImplDX12_ViewportData*)viewport->RendererUserData;
+
+    vd->SwapChain->Present(0, bd->tearingSupport ? DXGI_PRESENT_ALLOW_TEARING : 0);
+}
+
+void ImGui_ImplDX12_InitMultiViewportSupport()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_CreateWindow = ImGui_ImplDX12_CreateWindow;
+    platform_io.Renderer_DestroyWindow = ImGui_ImplDX12_DestroyWindow;
+    platform_io.Renderer_SetWindowSize = ImGui_ImplDX12_SetWindowSize;
+    platform_io.Renderer_RenderWindow = ImGui_ImplDX12_RenderWindow;
+    platform_io.Renderer_SwapBuffers = ImGui_ImplDX12_SwapBuffers;
+}
+
+void ImGui_ImplDX12_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
 //-----------------------------------------------------------------------------
 
 #endif // #ifndef IMGUI_DISABLE

diff --git a/backends/imgui_impl_dx12.h b/backends/imgui_impl_dx12.h
index b8be8db..97dcc0f 100644
--- a/backends/imgui_impl_dx12.h
+++ b/backends/imgui_impl_dx12.h

@@ -6,6 +6,7 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // The aim of imgui_impl_dx12.h/.cpp is to be usable in your engine without any modification.
 // IF YOU FEEL YOU NEED TO MAKE ANY CHANGE TO THIS CODE, please share them and your feedback at https://github.com/ocornut/imgui/

diff --git a/backends/imgui_impl_dx9.cpp b/backends/imgui_impl_dx9.cpp
index 37b5815..2ccf231 100644
--- a/backends/imgui_impl_dx9.cpp
+++ b/backends/imgui_impl_dx9.cpp

@@ -6,6 +6,7 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: IMGUI_USE_BGRA_PACKED_COLOR support, as this is the optimal color encoding for DirectX9.
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -17,6 +18,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-11: DirectX9: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas.
 //  2024-10-07: DirectX9: Changed default texture sampler to Clamp instead of Repeat/Wrap.
@@ -87,6 +89,12 @@
     return ImGui::GetCurrentContext() ? (ImGui_ImplDX9_Data*)ImGui::GetIO().BackendRendererUserData : nullptr;
 }
 
+// Forward Declarations
+static void ImGui_ImplDX9_InitMultiViewportSupport();
+static void ImGui_ImplDX9_ShutdownMultiViewportSupport();
+static void ImGui_ImplDX9_CreateDeviceObjectsForPlatformWindows();
+static void ImGui_ImplDX9_InvalidateDeviceObjectsForPlatformWindows();
+
 // Functions
 static void ImGui_ImplDX9_SetupRenderState(ImDrawData* draw_data)
 {
@@ -296,6 +304,11 @@
         global_vtx_offset += draw_list->VtxBuffer.Size;
     }
 
+    // When using multi-viewports, it appears that there's an odd logic in DirectX9 which prevent subsequent windows
+    // from rendering until the first window submits at least one draw call, even once. That's our workaround. (see #2560)
+    if (global_vtx_offset == 0)
+        bd->pd3dDevice->DrawIndexedPrimitive(D3DPT_TRIANGLELIST, 0, 0, 0, 0, 0);
+
     // Restore the DX9 transform
     device->SetTransform(D3DTS_WORLD, &last_world);
     device->SetTransform(D3DTS_VIEW, &last_view);
@@ -336,6 +349,7 @@
     io.BackendRendererName = "imgui_impl_dx9";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
     io.BackendFlags |= ImGuiBackendFlags_RendererHasTextures;   // We can honor ImGuiPlatformIO::Textures[] requests during render.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)
 
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
     platform_io.Renderer_TextureMaxWidth = platform_io.Renderer_TextureMaxHeight = 4096;
@@ -344,6 +358,8 @@
     bd->pd3dDevice->AddRef();
     bd->HasRgbaSupport = ImGui_ImplDX9_CheckFormatSupport(bd->pd3dDevice, D3DFMT_A8B8G8R8);
 
+    ImGui_ImplDX9_InitMultiViewportSupport();
+
     return true;
 }
 
@@ -354,12 +370,13 @@
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
+    ImGui_ImplDX9_ShutdownMultiViewportSupport();
     ImGui_ImplDX9_InvalidateDeviceObjects();
     if (bd->pd3dDevice) { bd->pd3dDevice->Release(); }
 
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures);
+    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
     platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
@@ -448,6 +465,7 @@
     ImGui_ImplDX9_Data* bd = ImGui_ImplDX9_GetBackendData();
     if (!bd || !bd->pd3dDevice)
         return false;
+    ImGui_ImplDX9_CreateDeviceObjectsForPlatformWindows();
     return true;
 }
 
@@ -466,6 +484,7 @@
         }
     if (bd->pVB) { bd->pVB->Release(); bd->pVB = nullptr; }
     if (bd->pIB) { bd->pIB->Release(); bd->pIB = nullptr; }
+    ImGui_ImplDX9_InvalidateDeviceObjectsForPlatformWindows();
 }
 
 void ImGui_ImplDX9_NewFrame()
@@ -475,6 +494,148 @@
     IM_UNUSED(bd);
 }
 
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* RendererUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGui_ImplDX9_ViewportData
+{
+    IDirect3DSwapChain9*    SwapChain;
+    D3DPRESENT_PARAMETERS   d3dpp;
+
+    ImGui_ImplDX9_ViewportData()  { SwapChain = nullptr; ZeroMemory(&d3dpp, sizeof(D3DPRESENT_PARAMETERS)); }
+    ~ImGui_ImplDX9_ViewportData() { IM_ASSERT(SwapChain == nullptr); }
+};
+
+static void ImGui_ImplDX9_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplDX9_Data* bd = ImGui_ImplDX9_GetBackendData();
+    ImGui_ImplDX9_ViewportData* vd = IM_NEW(ImGui_ImplDX9_ViewportData)();
+    viewport->RendererUserData = vd;
+
+    // PlatformHandleRaw should always be a HWND, whereas PlatformHandle might be a higher-level handle (e.g. GLFWWindow*, SDL's WindowID).
+    // Some backends will leave PlatformHandleRaw == 0, in which case we assume PlatformHandle will contain the HWND.
+    HWND hwnd = viewport->PlatformHandleRaw ? (HWND)viewport->PlatformHandleRaw : (HWND)viewport->PlatformHandle;
+    IM_ASSERT(hwnd != 0);
+
+    ZeroMemory(&vd->d3dpp, sizeof(D3DPRESENT_PARAMETERS));
+    vd->d3dpp.Windowed = TRUE;
+    vd->d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
+    vd->d3dpp.BackBufferWidth = (UINT)viewport->Size.x;
+    vd->d3dpp.BackBufferHeight = (UINT)viewport->Size.y;
+    vd->d3dpp.BackBufferFormat = D3DFMT_UNKNOWN;
+    vd->d3dpp.hDeviceWindow = hwnd;
+    vd->d3dpp.EnableAutoDepthStencil = FALSE;
+    vd->d3dpp.AutoDepthStencilFormat = D3DFMT_D16;
+    vd->d3dpp.PresentationInterval = D3DPRESENT_INTERVAL_IMMEDIATE;   // Present without vsync
+
+    HRESULT hr = bd->pd3dDevice->CreateAdditionalSwapChain(&vd->d3dpp, &vd->SwapChain); IM_UNUSED(hr);
+    IM_ASSERT(hr == D3D_OK);
+    IM_ASSERT(vd->SwapChain != nullptr);
+}
+
+static void ImGui_ImplDX9_DestroyWindow(ImGuiViewport* viewport)
+{
+    // The main viewport (owned by the application) will always have RendererUserData == 0 since we didn't create the data for it.
+    if (ImGui_ImplDX9_ViewportData* vd = (ImGui_ImplDX9_ViewportData*)viewport->RendererUserData)
+    {
+        if (vd->SwapChain)
+            vd->SwapChain->Release();
+        vd->SwapChain = nullptr;
+        ZeroMemory(&vd->d3dpp, sizeof(D3DPRESENT_PARAMETERS));
+        IM_DELETE(vd);
+    }
+    viewport->RendererUserData = nullptr;
+}
+
+static void ImGui_ImplDX9_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGui_ImplDX9_Data* bd = ImGui_ImplDX9_GetBackendData();
+    ImGui_ImplDX9_ViewportData* vd = (ImGui_ImplDX9_ViewportData*)viewport->RendererUserData;
+    if (vd->SwapChain)
+    {
+        vd->SwapChain->Release();
+        vd->SwapChain = nullptr;
+        vd->d3dpp.BackBufferWidth = (UINT)size.x;
+        vd->d3dpp.BackBufferHeight = (UINT)size.y;
+        HRESULT hr = bd->pd3dDevice->CreateAdditionalSwapChain(&vd->d3dpp, &vd->SwapChain); IM_UNUSED(hr);
+        IM_ASSERT(hr == D3D_OK);
+    }
+}
+
+static void ImGui_ImplDX9_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplDX9_Data* bd = ImGui_ImplDX9_GetBackendData();
+    ImGui_ImplDX9_ViewportData* vd = (ImGui_ImplDX9_ViewportData*)viewport->RendererUserData;
+    ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+
+    LPDIRECT3DSURFACE9 render_target = nullptr;
+    LPDIRECT3DSURFACE9 last_render_target = nullptr;
+    LPDIRECT3DSURFACE9 last_depth_stencil = nullptr;
+    vd->SwapChain->GetBackBuffer(0, D3DBACKBUFFER_TYPE_MONO, &render_target);
+    bd->pd3dDevice->GetRenderTarget(0, &last_render_target);
+    bd->pd3dDevice->GetDepthStencilSurface(&last_depth_stencil);
+    bd->pd3dDevice->SetRenderTarget(0, render_target);
+    bd->pd3dDevice->SetDepthStencilSurface(nullptr);
+
+    if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
+    {
+        D3DCOLOR clear_col_dx = D3DCOLOR_RGBA((int)(clear_color.x*255.0f), (int)(clear_color.y*255.0f), (int)(clear_color.z*255.0f), (int)(clear_color.w*255.0f));
+        bd->pd3dDevice->Clear(0, nullptr, D3DCLEAR_TARGET, clear_col_dx, 1.0f, 0);
+    }
+
+    ImGui_ImplDX9_RenderDrawData(viewport->DrawData);
+
+    // Restore render target
+    bd->pd3dDevice->SetRenderTarget(0, last_render_target);
+    bd->pd3dDevice->SetDepthStencilSurface(last_depth_stencil);
+    render_target->Release();
+    last_render_target->Release();
+    if (last_depth_stencil) last_depth_stencil->Release();
+}
+
+static void ImGui_ImplDX9_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplDX9_ViewportData* vd = (ImGui_ImplDX9_ViewportData*)viewport->RendererUserData;
+    HRESULT hr = vd->SwapChain->Present(nullptr, nullptr, vd->d3dpp.hDeviceWindow, nullptr, 0);
+    // Let main application handle D3DERR_DEVICELOST by resetting the device.
+    IM_ASSERT(SUCCEEDED(hr) || hr == D3DERR_DEVICELOST);
+}
+
+static void ImGui_ImplDX9_InitMultiViewportSupport()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_CreateWindow = ImGui_ImplDX9_CreateWindow;
+    platform_io.Renderer_DestroyWindow = ImGui_ImplDX9_DestroyWindow;
+    platform_io.Renderer_SetWindowSize = ImGui_ImplDX9_SetWindowSize;
+    platform_io.Renderer_RenderWindow = ImGui_ImplDX9_RenderWindow;
+    platform_io.Renderer_SwapBuffers = ImGui_ImplDX9_SwapBuffers;
+}
+
+static void ImGui_ImplDX9_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
+static void ImGui_ImplDX9_CreateDeviceObjectsForPlatformWindows()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int i = 1; i < platform_io.Viewports.Size; i++)
+        if (!platform_io.Viewports[i]->RendererUserData)
+            ImGui_ImplDX9_CreateWindow(platform_io.Viewports[i]);
+}
+
+static void ImGui_ImplDX9_InvalidateDeviceObjectsForPlatformWindows()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int i = 1; i < platform_io.Viewports.Size; i++)
+        if (platform_io.Viewports[i]->RendererUserData)
+            ImGui_ImplDX9_DestroyWindow(platform_io.Viewports[i]);
+}
+
 //-----------------------------------------------------------------------------
 
 #endif // #ifndef IMGUI_DISABLE

diff --git a/backends/imgui_impl_dx9.h b/backends/imgui_impl_dx9.h
index 021439b..59762e6 100644
--- a/backends/imgui_impl_dx9.h
+++ b/backends/imgui_impl_dx9.h

@@ -6,6 +6,7 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: IMGUI_USE_BGRA_PACKED_COLOR support, as this is the optimal color encoding for DirectX9.
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_glfw.cpp b/backends/imgui_impl_glfw.cpp
index da54589..e5e3096 100644
--- a/backends/imgui_impl_glfw.cpp
+++ b/backends/imgui_impl_glfw.cpp

@@ -9,10 +9,12 @@
 //  [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy GLFW_KEY_* values are obsolete since 1.87 and not supported since 1.91.5]
 //  [X] Platform: Gamepad support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
 //  [X] Platform: Mouse cursor shape and visibility (ImGuiBackendFlags_HasMouseCursors) with GLFW 3.1+. Resizing cursors requires GLFW 3.4+! Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 //  [X] Multiple Dear ImGui contexts support.
 // Missing features or Issues:
 //  [ ] Platform: Touch events are only correctly identified as Touch on Windows. This create issues with some interactions. GLFW doesn't provide a way to identify touch inputs from mouse inputs, we cannot call io.AddMouseSourceEvent() to identify the source. We provide a Windows-specific workaround.
 //  [ ] Platform: Missing ImGuiMouseCursor_Wait and ImGuiMouseCursor_Progress cursors.
+//  [ ] Platform: Multi-viewport: Missing ImGuiBackendFlags_HasParentViewport support. The viewport->ParentViewportID field is ignored, and therefore io.ConfigViewportsNoDefaultParent has no effect either.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -29,17 +31,25 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2026-02-10: Try to set IMGUI_IMPL_GLFW_DISABLE_X11 / IMGUI_IMPL_GLFW_DISABLE_WAYLAND automatically if corresponding headers are not accessible. (#9225)
+//  2026-01-25: [Docking] Improve workarounds for cases where GLFW is unable to provide any reliable monitor info. Preserve existing monitor list when none of the new one is valid. (#9195, #7902, #5683)
+//  2026-01-18: [Docking] Dynamically load X11 functions to avoid -lx11 linking requirement introduced on 2025-09-10.
 //  2025-12-12: Added IMGUI_IMPL_GLFW_DISABLE_X11 / IMGUI_IMPL_GLFW_DISABLE_WAYLAND to forcefully disable either.
 //  2025-12-10: Avoid repeated glfwSetCursor()/glfwSetInputMode() calls when unnecessary. Lowers overhead for very high framerates (e.g. 10k+ FPS).
 //  2025-11-06: Lower minimum requirement to GLFW 3.0. Though a recent version e.g GLFW 3.4 is highly recommended.
 //  2025-09-18: Call platform_io.ClearPlatformHandlers() on shutdown.
 //  2025-09-15: Content Scales are always reported as 1.0 on Wayland. FramebufferScale are always reported as 1.0 on X11. (#8920, #8921)
+//  2025-09-10: [Docking] Improve multi-viewport behavior in tiling WMs on X11 via the ImGui_ImplGlfw_SetWindowFloating() function. Note: using GLFW backend on Linux/BSD etc. requires linking with -lX11. (#8884, #8474, #8289)
 //  2025-07-08: Made ImGui_ImplGlfw_GetContentScaleForWindow(), ImGui_ImplGlfw_GetContentScaleForMonitor() helpers return 1.0f on Emscripten and Android platforms, matching macOS logic. (#8742, #8733)
 //  2025-06-18: Added support for multiple Dear ImGui contexts. (#8676, #8239, #8069)
 //  2025-06-11: Added ImGui_ImplGlfw_GetContentScaleForWindow(GLFWwindow* window) and ImGui_ImplGlfw_GetContentScaleForMonitor(GLFWmonitor* monitor) helper to facilitate making DPI-aware apps.
+//  2025-05-15: [Docking] Add Platform_GetWindowFramebufferScale() handler, to allow varying Retina display density on multiple monitors.
+//  2025-04-26: [Docking] Disable multi-viewports under Wayland. (#8587)
 //  2025-03-10: Map GLFW_KEY_WORLD_1 and GLFW_KEY_WORLD_2 into ImGuiKey_Oem102.
 //  2025-03-03: Fixed clipboard handler assertion when using GLFW <= 3.2.1 compiled with asserts enabled.
+//  2025-02-21: [Docking] Update monitors and work areas information every frame, as the later may change regardless of monitor changes. (#8415)
+//  2024-11-05: [Docking] Added Linux workaround for spurious mouse up events emitted while dragging and creating new viewport. (#3158, #7733, #7922)
 //  2024-08-22: Moved some OS/backend related function pointers from ImGuiIO to ImGuiPlatformIO:
 //               - io.GetClipboardTextFn    -> platform_io.Platform_GetClipboardTextFn
 //               - io.SetClipboardTextFn    -> platform_io.Platform_SetClipboardTextFn
@@ -56,6 +66,7 @@
 //  2023-03-16: Inputs: Fixed key modifiers handling on secondary viewports (docking branch). Broken on 2023/01/04. (#6248, #6034)
 //  2023-03-14: Emscripten: Avoid using glfwGetError() and glfwGetGamepadState() which are not correctly implemented in Emscripten emulation. (#6240)
 //  2023-02-03: Emscripten: Registering custom low-level mouse wheel handler to get more accurate scrolling impulses on Emscripten. (#4019, #6096)
+//  2023-01-18: Handle unsupported glfwGetVideoMode() call on e.g. Emscripten.
 //  2023-01-04: Inputs: Fixed mods state on Linux when using Alt-GR text input (e.g. German keyboard layout), could lead to broken text input. Revert a 2022/01/17 change were we resumed using mods provided by GLFW, turns out they were faulty.
 //  2022-11-22: Perform a dummy glfwGetError() read to cancel missing names with glfwGetKeyName(). (#5908)
 //  2022-10-18: Perform a dummy glfwGetError() read to cancel missing mouse cursors errors. Using GLFW_VERSION_COMBINED directly. (#5785)
@@ -108,6 +119,8 @@
 #pragma clang diagnostic ignored "-Wsign-conversion"        // warning: implicit conversion changes signedness
 #pragma clang diagnostic ignored "-Wexit-time-destructors"  // warning: declaration requires an exit-time destructor     // exit-time destruction order is undefined. if MemFree() leads to users code that has been disabled before exit it might cause problems. ImGui coding style welcomes static/globals.
 #pragma clang diagnostic ignored "-Wglobal-constructors"    // warning: declaration requires a global destructor         // similar to above, not sure what the exact difference is.
+#elif defined(__GNUC__)
+#pragma GCC diagnostic ignored "-Wfloat-equal"              // warning: comparing floating-point with '==' or '!=' is unsafe
 #endif
 
 #if defined(__has_include)
@@ -145,10 +158,13 @@
 #elif GLFW_HAS_X11
 #ifndef GLFW_EXPOSE_NATIVE_X11      // for glfwGetX11Display(), glfwGetX11Window() on Freedesktop (Linux, BSD, etc.)
 #define GLFW_EXPOSE_NATIVE_X11
+#include <X11/Xatom.h>
+#include <dlfcn.h>              // for dlopen()
 #endif
 #include <GLFW/glfw3native.h>
-#endif
 #undef Status                   // X11 headers are leaking this.
+#endif
+
 #ifndef _WIN32
 #include <unistd.h>             // for usleep()
 #endif
@@ -167,12 +183,29 @@
 // We gather version tests as define in order to easily see which features are version-dependent.
 #define GLFW_VERSION_COMBINED           (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 + GLFW_VERSION_REVISION)
 #define GLFW_HAS_CREATECURSOR           (GLFW_VERSION_COMBINED >= 3100) // 3.1+ glfwCreateCursor()
+#define GLFW_HAS_WINDOW_TOPMOST         (GLFW_VERSION_COMBINED >= 3200) // 3.2+ GLFW_FLOATING
+#define GLFW_HAS_WINDOW_HOVERED         (GLFW_VERSION_COMBINED >= 3300) // 3.3+ GLFW_HOVERED
+#define GLFW_HAS_WINDOW_ALPHA           (GLFW_VERSION_COMBINED >= 3300) // 3.3+ glfwSetWindowOpacity
 #define GLFW_HAS_PER_MONITOR_DPI        (GLFW_VERSION_COMBINED >= 3300) // 3.3+ glfwGetMonitorContentScale
+#if defined(__EMSCRIPTEN__) || defined(__SWITCH__)                      // no Vulkan support in GLFW for Emscripten or homebrew Nintendo Switch
+#define GLFW_HAS_VULKAN                 (0)
+#else
+#define GLFW_HAS_VULKAN                 (GLFW_VERSION_COMBINED >= 3200) // 3.2+ glfwCreateWindowSurface
+#endif
+#define GLFW_HAS_FOCUS_WINDOW           (GLFW_VERSION_COMBINED >= 3200) // 3.2+ glfwFocusWindow
+#define GLFW_HAS_FOCUS_ON_SHOW          (GLFW_VERSION_COMBINED >= 3300) // 3.3+ GLFW_FOCUS_ON_SHOW
+#define GLFW_HAS_MONITOR_WORK_AREA      (GLFW_VERSION_COMBINED >= 3300) // 3.3+ glfwGetMonitorWorkarea
+#define GLFW_HAS_OSX_WINDOW_POS_FIX     (GLFW_VERSION_COMBINED >= 3301) // 3.3.1+ Fixed: Resizing window repositions it on MacOS #1553
 #ifdef GLFW_RESIZE_NESW_CURSOR          // Let's be nice to people who pulled GLFW between 2019-04-16 (3.4 define) and 2019-11-29 (cursors defines) // FIXME: Remove when GLFW 3.4 is released?
 #define GLFW_HAS_NEW_CURSORS            (GLFW_VERSION_COMBINED >= 3400) // 3.4+ GLFW_RESIZE_ALL_CURSOR, GLFW_RESIZE_NESW_CURSOR, GLFW_RESIZE_NWSE_CURSOR, GLFW_NOT_ALLOWED_CURSOR
 #else
 #define GLFW_HAS_NEW_CURSORS            (0)
 #endif
+#ifdef GLFW_MOUSE_PASSTHROUGH           // Let's be nice to people who pulled GLFW between 2019-04-16 (3.4 define) and 2020-07-17 (passthrough)
+#define GLFW_HAS_MOUSE_PASSTHROUGH      (GLFW_VERSION_COMBINED >= 3400) // 3.4+ GLFW_MOUSE_PASSTHROUGH
+#else
+#define GLFW_HAS_MOUSE_PASSTHROUGH      (0)
+#endif
 #define GLFW_HAS_GAMEPAD_API            (GLFW_VERSION_COMBINED >= 3300) // 3.3+ glfwGetGamepadState() new api
 #define GLFW_HAS_GETKEYNAME             (GLFW_VERSION_COMBINED >= 3200) // 3.2+ glfwGetKeyName()
 #define GLFW_HAS_GETERROR               (GLFW_VERSION_COMBINED >= 3300) // 3.3+ glfwGetError()
@@ -195,6 +228,13 @@
     GlfwClientApi_Unknown,  // Anything else fits here.
 };
 
+#if GLFW_HAS_X11
+typedef Atom (*PFN_XInternAtom)(Display*, const char* ,Bool);
+typedef int  (*PFN_XChangeProperty)(Display*, Window, Atom, Atom, int, int, const unsigned char*, int);
+typedef int  (*PFN_XChangeWindowAttributes)(Display*, Window, unsigned long, XSetWindowAttributes*);
+typedef int  (*PFN_XFlush)(Display*);
+#endif
+
 // GLFW data
 struct ImGui_ImplGlfw_Data
 {
@@ -207,7 +247,10 @@
     GLFWcursor*             MouseCursors[ImGuiMouseCursor_COUNT];
     GLFWcursor*             LastMouseCursor;
 #endif
+    bool                    MouseIgnoreButtonUpWaitForFocusLoss;
+    bool                    MouseIgnoreButtonUp;
     ImVec2                  LastValidMousePos;
+    GLFWwindow*             KeyOwnerWindows[GLFW_KEY_LAST];
     bool                    IsWayland;
     bool                    InstalledCallbacks;
     bool                    CallbacksChainForAllWindows;
@@ -229,6 +272,15 @@
     WNDPROC                 PrevWndProc;
 #endif
 
+#if GLFW_HAS_X11
+    // Module and function pointers loaded at initialization to avoid linking statically with X11.
+    void*                       X11Module;
+    PFN_XInternAtom             XInternAtom;
+    PFN_XChangeProperty         XChangeProperty;
+    PFN_XChangeWindowAttributes XChangeWindowAttributes;
+    PFN_XFlush                  XFlush;
+#endif
+
     ImGui_ImplGlfw_Data()   { memset((void*)this, 0, sizeof(*this)); }
 };
 
@@ -252,6 +304,11 @@
     return (ImGui_ImplGlfw_Data*)ImGui::GetIO(ctx).BackendPlatformUserData;
 }
 
+// Forward Declarations
+static void ImGui_ImplGlfw_UpdateMonitors();
+static void ImGui_ImplGlfw_InitMultiViewportSupport();
+static void ImGui_ImplGlfw_ShutdownMultiViewportSupport();
+
 // Functions
 static bool ImGui_ImplGlfw_IsWayland()
 {
@@ -422,6 +479,10 @@
     if (bd->PrevUserCallbackMousebutton != nullptr && ImGui_ImplGlfw_ShouldChainCallback(bd, window))
         bd->PrevUserCallbackMousebutton(window, button, action, mods);
 
+    // Workaround for Linux: ignore mouse up events which are following an focus loss following a viewport creation
+    if (bd->MouseIgnoreButtonUp && action == GLFW_RELEASE)
+        return;
+
     ImGuiIO& io = ImGui::GetIO(bd->Context);
     ImGui_ImplGlfw_UpdateKeyModifiers(io, window);
     if (button >= 0 && button < ImGuiMouseButton_COUNT)
@@ -489,6 +550,9 @@
     ImGuiIO& io = ImGui::GetIO(bd->Context);
     ImGui_ImplGlfw_UpdateKeyModifiers(io, window);
 
+    if (keycode >= 0 && keycode < IM_COUNTOF(bd->KeyOwnerWindows))
+        bd->KeyOwnerWindows[keycode] = (action == GLFW_PRESS) ? window : nullptr;
+
     keycode = ImGui_ImplGlfw_TranslateUntranslatedKey(keycode, scancode);
 
     ImGuiKey imgui_key = ImGui_ImplGlfw_KeyToImGuiKey(keycode, scancode);
@@ -502,6 +566,10 @@
     if (bd->PrevUserCallbackWindowFocus != nullptr && ImGui_ImplGlfw_ShouldChainCallback(bd, window))
         bd->PrevUserCallbackWindowFocus(window, focused);
 
+    // Workaround for Linux: when losing focus with MouseIgnoreButtonUpWaitForFocusLoss set, we will temporarily ignore subsequent Mouse Up events
+    bd->MouseIgnoreButtonUp = (bd->MouseIgnoreButtonUpWaitForFocusLoss && focused == 0);
+    bd->MouseIgnoreButtonUpWaitForFocusLoss = false;
+
     ImGuiIO& io = ImGui::GetIO(bd->Context);
     io.AddFocusEvent(focused != 0);
 }
@@ -513,6 +581,13 @@
         bd->PrevUserCallbackCursorPos(window, x, y);
 
     ImGuiIO& io = ImGui::GetIO(bd->Context);
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        int window_x, window_y;
+        glfwGetWindowPos(window, &window_x, &window_y);
+        x += window_x;
+        y += window_y;
+    }
     io.AddMousePosEvent((float)x, (float)y);
     bd->LastValidMousePos = ImVec2((float)x, (float)y);
 }
@@ -551,7 +626,7 @@
 
 void ImGui_ImplGlfw_MonitorCallback(GLFWmonitor*, int)
 {
-    // Unused in 'master' branch but 'docking' branch will use this, so we declare it ahead of it so if you have to install callbacks you can install this one too.
+    // This function is technically part of the API even if we stopped using the callback, so leaving it around.
 }
 
 #ifdef EMSCRIPTEN_USE_EMBEDDED_GLFW3
@@ -574,35 +649,7 @@
 #endif
 
 #ifdef _WIN32
-// GLFW doesn't allow to distinguish Mouse vs TouchScreen vs Pen.
-// Add support for Win32 (based on imgui_impl_win32), because we rely on _TouchScreen info to trickle inputs differently.
-static ImGuiMouseSource GetMouseSourceFromMessageExtraInfo()
-{
-    LPARAM extra_info = ::GetMessageExtraInfo();
-    if ((extra_info & 0xFFFFFF80) == 0xFF515700)
-        return ImGuiMouseSource_Pen;
-    if ((extra_info & 0xFFFFFF80) == 0xFF515780)
-        return ImGuiMouseSource_TouchScreen;
-    return ImGuiMouseSource_Mouse;
-}
-static LRESULT CALLBACK ImGui_ImplGlfw_WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
-{
-    ImGui_ImplGlfw_Data* bd = (ImGui_ImplGlfw_Data*)::GetPropA(hWnd, "IMGUI_BACKEND_DATA");
-    ImGuiIO& io = ImGui::GetIO(bd->Context);
-
-    switch (msg)
-    {
-    case WM_MOUSEMOVE: case WM_NCMOUSEMOVE:
-    case WM_LBUTTONDOWN: case WM_LBUTTONDBLCLK: case WM_LBUTTONUP:
-    case WM_RBUTTONDOWN: case WM_RBUTTONDBLCLK: case WM_RBUTTONUP:
-    case WM_MBUTTONDOWN: case WM_MBUTTONDBLCLK: case WM_MBUTTONUP:
-    case WM_XBUTTONDOWN: case WM_XBUTTONDBLCLK: case WM_XBUTTONUP:
-        io.AddMouseSourceEvent(GetMouseSourceFromMessageExtraInfo());
-        break;
-    default: break;
-    }
-    return ::CallWindowProcW(bd->PrevWndProc, hWnd, msg, wParam, lParam);
-}
+static LRESULT CALLBACK ImGui_ImplGlfw_WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
 #endif
 
 void ImGui_ImplGlfw_InstallCallbacks(GLFWwindow* window)
@@ -682,6 +729,20 @@
 #endif
     io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;          // We can honor io.WantSetMousePos requests (optional, rarely used)
 
+    bool has_viewports = false;
+#ifndef __EMSCRIPTEN__
+    has_viewports = true;
+#if GLFW_HAS_GETPLATFORM
+    if (glfwGetPlatform() == GLFW_PLATFORM_WAYLAND)
+        has_viewports = false;
+#endif
+    if (has_viewports)
+        io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports;  // We can create multi-viewports on the Platform side (optional)
+#endif
+#if GLFW_HAS_MOUSE_PASSTHROUGH || GLFW_HAS_WINDOW_HOVERED
+    io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport; // We can call io.AddMouseViewportEvent() with correct data (optional)
+#endif
+
     bd->Context = ImGui::GetCurrentContext();
     bd->Window = window;
     bd->Time = 0.0;
@@ -733,6 +794,11 @@
     if (install_callbacks)
         ImGui_ImplGlfw_InstallCallbacks(window);
 
+    // Update monitor a first time during init
+    // (note: monitor callback are broken in GLFW 3.2 and earlier, see github.com/glfw/glfw/issues/784)
+    ImGui_ImplGlfw_UpdateMonitors();
+    glfwSetMonitorCallback(ImGui_ImplGlfw_MonitorCallback);
+
     // Set platform dependent data in viewport
     ImGuiViewport* main_viewport = ImGui::GetMainViewport();
     main_viewport->PlatformHandle = (void*)bd->Window;
@@ -743,6 +809,8 @@
 #else
     IM_UNUSED(main_viewport);
 #endif
+    if (has_viewports)
+        ImGui_ImplGlfw_InitMultiViewportSupport();
 
     // Windows: register a WndProc hook so we can intercept some messages.
 #ifdef _WIN32
@@ -753,6 +821,26 @@
     ::SetWindowLongPtrW((HWND)main_viewport->PlatformHandleRaw, GWLP_WNDPROC, (LONG_PTR)ImGui_ImplGlfw_WndProc);
 #endif
 
+#if GLFW_HAS_X11
+    if (!bd->IsWayland)
+    {
+        // Load X11 module dynamically. Copied from the way that GLFW does it in x11_init.c
+#if defined(__CYGWIN__)
+        const char* x11_module_path = "libX11-6.so";
+#elif defined(__OpenBSD__) || defined(__NetBSD__)
+        const char* x11_module_path = "libX11.so";
+#else
+        const char* x11_module_path = "libX11.so.6";
+#endif
+        bd->X11Module = dlopen(x11_module_path, RTLD_LAZY | RTLD_LOCAL);
+        bd->XInternAtom = (PFN_XInternAtom)dlsym(bd->X11Module, "XInternAtom");
+        bd->XChangeProperty = (PFN_XChangeProperty)dlsym(bd->X11Module, "XChangeProperty");
+        bd->XChangeWindowAttributes = (PFN_XChangeWindowAttributes)dlsym(bd->X11Module, "XChangeWindowAttributes");
+        bd->XFlush = (PFN_XFlush)dlsym(bd->X11Module, "XFlush");
+        IM_ASSERT(bd->XInternAtom != nullptr && bd->XChangeProperty != nullptr && bd->XChangeWindowAttributes != nullptr && bd->XFlush != nullptr);
+    }
+#endif
+
     // Emscripten: the same application can run on various platforms, so we detect the Apple platform at runtime
     // to override io.ConfigMacOSXBehaviors from its default (which is always false in Emscripten).
 #ifdef __EMSCRIPTEN__
@@ -797,6 +885,7 @@
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
+    ImGui_ImplGlfw_ShutdownMultiViewportSupport();
     if (bd->InstalledCallbacks)
         ImGui_ImplGlfw_RestoreCallbacks(bd->Window);
 #ifdef EMSCRIPTEN_USE_EMBEDDED_GLFW3
@@ -815,9 +904,14 @@
     bd->PrevWndProc = nullptr;
 #endif
 
+#if GLFW_HAS_X11
+    if (bd->X11Module != nullptr)
+        dlclose(bd->X11Module);
+#endif
+
     io.BackendPlatformName = nullptr;
     io.BackendPlatformUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad);
+    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad | ImGuiBackendFlags_PlatformHasViewports | ImGuiBackendFlags_HasMouseHoveredViewport);
     platform_io.ClearPlatformHandlers();
     ImGui_ImplGlfw_ContextMap_Remove(bd->Window);
     IM_DELETE(bd);
@@ -827,10 +921,15 @@
 {
     ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
-    // (those braces are here to reduce diff with multi-viewports support in 'docking' branch)
+    ImGuiID mouse_viewport_id = 0;
+    const ImVec2 mouse_pos_prev = io.MousePos;
+    for (int n = 0; n < platform_io.Viewports.Size; n++)
     {
-        GLFWwindow* window = bd->Window;
+        ImGuiViewport* viewport = platform_io.Viewports[n];
+        GLFWwindow* window = (GLFWwindow*)viewport->PlatformHandle;
+
 #ifdef EMSCRIPTEN_USE_EMBEDDED_GLFW3
         const bool is_window_focused = true;
 #else
@@ -839,19 +938,54 @@
         if (is_window_focused)
         {
             // (Optional) Set OS mouse position from Dear ImGui if requested (rarely used, only when io.ConfigNavMoveSetMousePos is enabled by user)
+            // When multi-viewports are enabled, all Dear ImGui positions are same as OS positions.
             if (io.WantSetMousePos)
-                glfwSetCursorPos(window, (double)io.MousePos.x, (double)io.MousePos.y);
+                glfwSetCursorPos(window, (double)(mouse_pos_prev.x - viewport->Pos.x), (double)(mouse_pos_prev.y - viewport->Pos.y));
 
             // (Optional) Fallback to provide mouse position when focused (ImGui_ImplGlfw_CursorPosCallback already provides this when hovered or captured)
             if (bd->MouseWindow == nullptr)
             {
                 double mouse_x, mouse_y;
                 glfwGetCursorPos(window, &mouse_x, &mouse_y);
+                if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+                {
+                    // Single viewport mode: mouse position in client window coordinates (io.MousePos is (0,0) when the mouse is on the upper-left corner of the app window)
+                    // Multi-viewport mode: mouse position in OS absolute coordinates (io.MousePos is (0,0) when the mouse is on the upper-left of the primary monitor)
+                    int window_x, window_y;
+                    glfwGetWindowPos(window, &window_x, &window_y);
+                    mouse_x += window_x;
+                    mouse_y += window_y;
+                }
                 bd->LastValidMousePos = ImVec2((float)mouse_x, (float)mouse_y);
                 io.AddMousePosEvent((float)mouse_x, (float)mouse_y);
             }
         }
+
+        // (Optional) When using multiple viewports: call io.AddMouseViewportEvent() with the viewport the OS mouse cursor is hovering.
+        // If ImGuiBackendFlags_HasMouseHoveredViewport is not set by the backend, Dear imGui will ignore this field and infer the information using its flawed heuristic.
+        // - [X] GLFW >= 3.3 backend ON WINDOWS ONLY does correctly ignore viewports with the _NoInputs flag (since we implement hit via our WndProc hook)
+        //       On other platforms we rely on the library fallbacking to its own search when reporting a viewport with _NoInputs flag.
+        // - [!] GLFW <= 3.2 backend CANNOT correctly ignore viewports with the _NoInputs flag, and CANNOT reported Hovered Viewport because of mouse capture.
+        //       Some backend are not able to handle that correctly. If a backend report an hovered viewport that has the _NoInputs flag (e.g. when dragging a window
+        //       for docking, the viewport has the _NoInputs flag in order to allow us to find the viewport under), then Dear ImGui is forced to ignore the value reported
+        //       by the backend, and use its flawed heuristic to guess the viewport behind.
+        // - [X] GLFW backend correctly reports this regardless of another viewport behind focused and dragged from (we need this to find a useful drag and drop target).
+        // FIXME: This is currently only correct on Win32. See what we do below with the WM_NCHITTEST, missing an equivalent for other systems.
+        // See https://github.com/glfw/glfw/issues/1236 if you want to help in making this a GLFW feature.
+#if GLFW_HAS_MOUSE_PASSTHROUGH
+        const bool window_no_input = (viewport->Flags & ImGuiViewportFlags_NoInputs) != 0;
+        glfwSetWindowAttrib(window, GLFW_MOUSE_PASSTHROUGH, window_no_input);
+#endif
+#if GLFW_HAS_MOUSE_PASSTHROUGH || GLFW_HAS_WINDOW_HOVERED
+        if (glfwGetWindowAttrib(window, GLFW_HOVERED))
+            mouse_viewport_id = viewport->ID;
+#else
+        // We cannot use bd->MouseWindow maintained from CursorEnter/Leave callbacks, because it is locked to the window capturing mouse.
+#endif
     }
+
+    if (io.BackendFlags & ImGuiBackendFlags_HasMouseHoveredViewport)
+        io.AddMouseViewportEvent(mouse_viewport_id);
 }
 
 static void ImGui_ImplGlfw_UpdateMouseCursor()
@@ -862,9 +996,10 @@
         return;
 
     ImGuiMouseCursor imgui_cursor = ImGui::GetMouseCursor();
-    // (those braces are here to reduce diff with multi-viewports support in 'docking' branch)
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int n = 0; n < platform_io.Viewports.Size; n++)
     {
-        GLFWwindow* window = bd->Window;
+        GLFWwindow* window = (GLFWwindow*)platform_io.Viewports[n]->PlatformHandle;
         if (imgui_cursor == ImGuiMouseCursor_None || io.MouseDrawCursor)
         {
             if (bd->LastMouseCursor != nullptr)
@@ -944,6 +1079,49 @@
     #undef MAP_ANALOG
 }
 
+static void ImGui_ImplGlfw_UpdateMonitors()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    int monitors_count = 0;
+    GLFWmonitor** glfw_monitors = glfwGetMonitors(&monitors_count);
+
+    bool updated_monitors = false;
+    for (int n = 0; n < monitors_count; n++)
+    {
+        ImGuiPlatformMonitor monitor;
+        int x, y;
+        glfwGetMonitorPos(glfw_monitors[n], &x, &y);
+        const GLFWvidmode* vid_mode = glfwGetVideoMode(glfw_monitors[n]);
+        if (vid_mode == nullptr)
+            continue; // Failed to get Video mode (e.g. Emscripten does not support this function)
+        if (vid_mode->width <= 0 || vid_mode->height <= 0)
+            continue; // Failed to query suitable monitor info (#9195)
+        monitor.MainPos = monitor.WorkPos = ImVec2((float)x, (float)y);
+        monitor.MainSize = monitor.WorkSize = ImVec2((float)vid_mode->width, (float)vid_mode->height);
+#if GLFW_HAS_MONITOR_WORK_AREA
+        int w, h;
+        glfwGetMonitorWorkarea(glfw_monitors[n], &x, &y, &w, &h);
+        if (w > 0 && h > 0) // Workaround a small GLFW issue reporting zero on monitor changes: https://github.com/glfw/glfw/pull/1761
+        {
+            monitor.WorkPos = ImVec2((float)x, (float)y);
+            monitor.WorkSize = ImVec2((float)w, (float)h);
+        }
+#endif
+        float scale = ImGui_ImplGlfw_GetContentScaleForMonitor(glfw_monitors[n]);
+        if (scale == 0.0f)
+            continue; // Some accessibility applications are declaring virtual monitors with a DPI of 0 (#7902)
+        monitor.DpiScale = scale;
+        monitor.PlatformHandle = (void*)glfw_monitors[n]; // [...] GLFW doc states: "guaranteed to be valid only until the monitor configuration changes"
+
+        // Preserve existing monitor list until a valid one is added.
+        // Happens on macOS sleeping (#5683) and seemingly occasionally on Windows (#9195)
+        if (!updated_monitors)
+            platform_io.Monitors.resize(0);
+        updated_monitors = true;
+        platform_io.Monitors.push_back(monitor);
+    }
+}
+
 // - On Windows the process needs to be marked DPI-aware!! SDL2 doesn't do it by default. You can call ::SetProcessDPIAware() or call ImGui_ImplWin32_EnableDpiAwareness() from Win32 backend.
 // - Apple platforms use FramebufferScale so we always return 1.0f.
 // - Some accessibility applications are declaring virtual monitors with a DPI of 0.0f, see #7902. We preserve this value for caller to handle.
@@ -1007,6 +1185,7 @@
 
     // Setup main viewport size (every frame to accommodate for window resizing)
     ImGui_ImplGlfw_GetWindowSizeAndFramebufferScale(bd->Window, &io.DisplaySize, &io.DisplayFramebufferScale);
+    ImGui_ImplGlfw_UpdateMonitors();
 
     // Setup time step
     // (Accept glfwGetTime() not returning a monotonically increasing value. Seems to happens on disconnecting peripherals and probably on VMs and Emscripten, see #6491, #6189, #6114, #3644)
@@ -1016,6 +1195,7 @@
     io.DeltaTime = bd->Time > 0.0 ? (float)(current_time - bd->Time) : (float)(1.0f / 60.0f);
     bd->Time = current_time;
 
+    bd->MouseIgnoreButtonUp = false;
     ImGui_ImplGlfw_UpdateMouseData();
     ImGui_ImplGlfw_UpdateMouseCursor();
 
@@ -1085,6 +1265,444 @@
 }
 #endif // #ifdef EMSCRIPTEN_USE_PORT_CONTRIB_GLFW3
 
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* PlatformUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGui_ImplGlfw_ViewportData
+{
+    GLFWwindow* Window;             // Stored in ImGuiViewport::PlatformHandle
+    bool        WindowOwned;
+    int         IgnoreWindowPosEventFrame;
+    int         IgnoreWindowSizeEventFrame;
+#ifdef _WIN32
+    WNDPROC     PrevWndProc;
+#endif
+
+    ImGui_ImplGlfw_ViewportData()  { memset((void*)this, 0, sizeof(*this)); IgnoreWindowSizeEventFrame = IgnoreWindowPosEventFrame = -1; }
+    ~ImGui_ImplGlfw_ViewportData() { IM_ASSERT(Window == nullptr); }
+};
+
+static void ImGui_ImplGlfw_WindowCloseCallback(GLFWwindow* window)
+{
+    if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle(window))
+        viewport->PlatformRequestClose = true;
+}
+
+// GLFW may dispatch window pos/size events after calling glfwSetWindowPos()/glfwSetWindowSize().
+// However: depending on the platform the callback may be invoked at different time:
+// - on Windows it appears to be called within the glfwSetWindowPos()/glfwSetWindowSize() call
+// - on Linux it is queued and invoked during glfwPollEvents()
+// Because the event doesn't always fire on glfwSetWindowXXX() we use a frame counter tag to only
+// ignore recent glfwSetWindowXXX() calls.
+static void ImGui_ImplGlfw_WindowPosCallback(GLFWwindow* window, int, int)
+{
+    if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle(window))
+    {
+        if (ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData)
+        {
+            bool ignore_event = (ImGui::GetFrameCount() <= vd->IgnoreWindowPosEventFrame + 1);
+            //data->IgnoreWindowPosEventFrame = -1;
+            if (ignore_event)
+                return;
+        }
+        viewport->PlatformRequestMove = true;
+    }
+}
+
+static void ImGui_ImplGlfw_WindowSizeCallback(GLFWwindow* window, int, int)
+{
+    if (ImGuiViewport* viewport = ImGui::FindViewportByPlatformHandle(window))
+    {
+        if (ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData)
+        {
+            bool ignore_event = (ImGui::GetFrameCount() <= vd->IgnoreWindowSizeEventFrame + 1);
+            //data->IgnoreWindowSizeEventFrame = -1;
+            if (ignore_event)
+                return;
+        }
+        viewport->PlatformRequestResize = true;
+    }
+}
+
+#if !defined(__APPLE__) && !defined(_WIN32) && !defined(__EMSCRIPTEN__) && GLFW_HAS_GETPLATFORM
+#define IMGUI_GLFW_HAS_SETWINDOWFLOATING
+static void ImGui_ImplGlfw_SetWindowFloating(ImGui_ImplGlfw_Data* bd, GLFWwindow* window)
+{
+#ifdef GLFW_EXPOSE_NATIVE_X11
+    if (glfwGetPlatform() == GLFW_PLATFORM_X11)
+    {
+        Display* display = glfwGetX11Display();
+        Window xwindow = glfwGetX11Window(window);
+        Atom wm_type = bd->XInternAtom(display, "_NET_WM_WINDOW_TYPE", False);
+        Atom wm_type_dialog = bd->XInternAtom(display, "_NET_WM_WINDOW_TYPE_DIALOG", False);
+        bd->XChangeProperty(display, xwindow, wm_type, XA_ATOM, 32, PropModeReplace, (unsigned char*)&wm_type_dialog, 1);
+        XSetWindowAttributes attrs;
+        attrs.override_redirect = False;
+        bd->XChangeWindowAttributes(display, xwindow, CWOverrideRedirect, &attrs);
+        bd->XFlush(display);
+    }
+#endif // GLFW_EXPOSE_NATIVE_X11
+#ifdef GLFW_EXPOSE_NATIVE_WAYLAND
+    // FIXME: Help needed, see #8884, #8474 for discussions about this.
+#endif // GLFW_EXPOSE_NATIVE_X11
+}
+#endif // IMGUI_GLFW_HAS_SETWINDOWFLOATING
+
+static void ImGui_ImplGlfw_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    ImGui_ImplGlfw_ViewportData* vd = IM_NEW(ImGui_ImplGlfw_ViewportData)();
+    viewport->PlatformUserData = vd;
+
+    // Workaround for Linux: ignore mouse up events corresponding to losing focus of the previously focused window (#7733, #3158, #7922)
+#ifdef __linux__
+    bd->MouseIgnoreButtonUpWaitForFocusLoss = true;
+#endif
+
+    // GLFW 3.2 unfortunately always set focus on glfwCreateWindow() if GLFW_VISIBLE is set, regardless of GLFW_FOCUSED
+    // With GLFW 3.3, the hint GLFW_FOCUS_ON_SHOW fixes this problem
+    glfwWindowHint(GLFW_VISIBLE, false);
+    glfwWindowHint(GLFW_FOCUSED, false);
+#if GLFW_HAS_FOCUS_ON_SHOW
+    glfwWindowHint(GLFW_FOCUS_ON_SHOW, false);
+#endif
+    glfwWindowHint(GLFW_DECORATED, (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? false : true);
+#if GLFW_HAS_WINDOW_TOPMOST
+    glfwWindowHint(GLFW_FLOATING, (viewport->Flags & ImGuiViewportFlags_TopMost) ? true : false);
+#endif
+    GLFWwindow* share_window = (bd->ClientApi == GlfwClientApi_OpenGL) ? bd->Window : nullptr;
+    vd->Window = glfwCreateWindow((int)viewport->Size.x, (int)viewport->Size.y, "No Title Yet", nullptr, share_window);
+    vd->WindowOwned = true;
+    ImGui_ImplGlfw_ContextMap_Add(vd->Window, bd->Context);
+    viewport->PlatformHandle = (void*)vd->Window;
+#ifdef IMGUI_GLFW_HAS_SETWINDOWFLOATING
+    ImGui_ImplGlfw_SetWindowFloating(bd, vd->Window);
+#endif
+#ifdef _WIN32
+    viewport->PlatformHandleRaw = glfwGetWin32Window(vd->Window);
+    ::SetPropA((HWND)viewport->PlatformHandleRaw, "IMGUI_BACKEND_DATA", bd);
+#elif defined(__APPLE__)
+    viewport->PlatformHandleRaw = (void*)glfwGetCocoaWindow(vd->Window);
+#endif
+    glfwSetWindowPos(vd->Window, (int)viewport->Pos.x, (int)viewport->Pos.y);
+
+    // Install GLFW callbacks for secondary viewports
+    glfwSetWindowFocusCallback(vd->Window, ImGui_ImplGlfw_WindowFocusCallback);
+    glfwSetCursorEnterCallback(vd->Window, ImGui_ImplGlfw_CursorEnterCallback);
+    glfwSetCursorPosCallback(vd->Window, ImGui_ImplGlfw_CursorPosCallback);
+    glfwSetMouseButtonCallback(vd->Window, ImGui_ImplGlfw_MouseButtonCallback);
+    glfwSetScrollCallback(vd->Window, ImGui_ImplGlfw_ScrollCallback);
+    glfwSetKeyCallback(vd->Window, ImGui_ImplGlfw_KeyCallback);
+    glfwSetCharCallback(vd->Window, ImGui_ImplGlfw_CharCallback);
+    glfwSetWindowCloseCallback(vd->Window, ImGui_ImplGlfw_WindowCloseCallback);
+    glfwSetWindowPosCallback(vd->Window, ImGui_ImplGlfw_WindowPosCallback);
+    glfwSetWindowSizeCallback(vd->Window, ImGui_ImplGlfw_WindowSizeCallback);
+    if (bd->ClientApi == GlfwClientApi_OpenGL)
+    {
+        glfwMakeContextCurrent(vd->Window);
+        glfwSwapInterval(0);
+    }
+}
+
+static void ImGui_ImplGlfw_DestroyWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    if (ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData)
+    {
+        if (vd->WindowOwned)
+        {
+#if !GLFW_HAS_MOUSE_PASSTHROUGH && GLFW_HAS_WINDOW_HOVERED && defined(_WIN32)
+            HWND hwnd = (HWND)viewport->PlatformHandleRaw;
+            ::RemovePropA(hwnd, "IMGUI_VIEWPORT");
+#endif
+
+            // Release any keys that were pressed in the window being destroyed and are still held down,
+            // because we will not receive any release events after window is destroyed.
+            for (int i = 0; i < IM_COUNTOF(bd->KeyOwnerWindows); i++)
+                if (bd->KeyOwnerWindows[i] == vd->Window)
+                    ImGui_ImplGlfw_KeyCallback(vd->Window, i, 0, GLFW_RELEASE, 0); // Later params are only used for main viewport, on which this function is never called.
+
+            ImGui_ImplGlfw_ContextMap_Remove(vd->Window);
+            glfwDestroyWindow(vd->Window);
+        }
+        vd->Window = nullptr;
+        IM_DELETE(vd);
+    }
+    viewport->PlatformUserData = viewport->PlatformHandle = nullptr;
+}
+
+static void ImGui_ImplGlfw_ShowWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+
+#if defined(_WIN32)
+    // GLFW hack: Hide icon from task bar
+    HWND hwnd = (HWND)viewport->PlatformHandleRaw;
+    if (viewport->Flags & ImGuiViewportFlags_NoTaskBarIcon)
+    {
+        LONG ex_style = ::GetWindowLong(hwnd, GWL_EXSTYLE);
+        ex_style &= ~WS_EX_APPWINDOW;
+        ex_style |= WS_EX_TOOLWINDOW;
+        ::SetWindowLong(hwnd, GWL_EXSTYLE, ex_style);
+    }
+
+    // GLFW hack: install WndProc for mouse source event and WM_NCHITTEST message handler.
+    ::SetPropA(hwnd, "IMGUI_VIEWPORT", viewport);
+    vd->PrevWndProc = (WNDPROC)::GetWindowLongPtrW(hwnd, GWLP_WNDPROC);
+    ::SetWindowLongPtrW(hwnd, GWLP_WNDPROC, (LONG_PTR)ImGui_ImplGlfw_WndProc);
+
+#if !GLFW_HAS_FOCUS_ON_SHOW
+    // GLFW hack: GLFW 3.2 has a bug where glfwShowWindow() also activates/focus the window.
+    // The fix was pushed to GLFW repository on 2018/01/09 and should be included in GLFW 3.3 via a GLFW_FOCUS_ON_SHOW window attribute.
+    // See https://github.com/glfw/glfw/issues/1189
+    // FIXME-VIEWPORT: Implement same work-around for Linux/OSX in the meanwhile.
+    if (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing)
+    {
+        ::ShowWindow(hwnd, SW_SHOWNA);
+        return;
+    }
+#endif
+#endif
+
+    glfwShowWindow(vd->Window);
+}
+
+static ImVec2 ImGui_ImplGlfw_GetWindowPos(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    int x = 0, y = 0;
+    glfwGetWindowPos(vd->Window, &x, &y);
+    return ImVec2((float)x, (float)y);
+}
+
+static void ImGui_ImplGlfw_SetWindowPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    vd->IgnoreWindowPosEventFrame = ImGui::GetFrameCount();
+    glfwSetWindowPos(vd->Window, (int)pos.x, (int)pos.y);
+}
+
+static ImVec2 ImGui_ImplGlfw_GetWindowSize(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    int w = 0, h = 0;
+    glfwGetWindowSize(vd->Window, &w, &h);
+    return ImVec2((float)w, (float)h);
+}
+
+static void ImGui_ImplGlfw_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+#if defined(__APPLE__) && !GLFW_HAS_OSX_WINDOW_POS_FIX
+    // Native OS windows are positioned from the bottom-left corner on macOS, whereas on other platforms they are
+    // positioned from the upper-left corner. GLFW makes an effort to convert macOS style coordinates, however it
+    // doesn't handle it when changing size. We are manually moving the window in order for changes of size to be based
+    // on the upper-left corner.
+    int x, y, width, height;
+    glfwGetWindowPos(vd->Window, &x, &y);
+    glfwGetWindowSize(vd->Window, &width, &height);
+    glfwSetWindowPos(vd->Window, x, y - height + size.y);
+#endif
+    vd->IgnoreWindowSizeEventFrame = ImGui::GetFrameCount();
+    glfwSetWindowSize(vd->Window, (int)size.x, (int)size.y);
+}
+
+static ImVec2 ImGui_ImplGlfw_GetWindowFramebufferScale(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    ImVec2 framebuffer_scale;
+    ImGui_ImplGlfw_GetWindowSizeAndFramebufferScale(vd->Window, nullptr, &framebuffer_scale);
+    return framebuffer_scale;
+}
+
+static void ImGui_ImplGlfw_SetWindowTitle(ImGuiViewport* viewport, const char* title)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    glfwSetWindowTitle(vd->Window, title);
+}
+
+static void ImGui_ImplGlfw_SetWindowFocus(ImGuiViewport* viewport)
+{
+#if GLFW_HAS_FOCUS_WINDOW
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    glfwFocusWindow(vd->Window);
+#else
+    // FIXME: What are the effect of not having this function? At the moment imgui doesn't actually call SetWindowFocus - we set that up ahead, will answer that question later.
+    (void)viewport;
+#endif
+}
+
+static bool ImGui_ImplGlfw_GetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    return glfwGetWindowAttrib(vd->Window, GLFW_FOCUSED) != 0;
+}
+
+static bool ImGui_ImplGlfw_GetWindowMinimized(ImGuiViewport* viewport)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    return glfwGetWindowAttrib(vd->Window, GLFW_ICONIFIED) != 0;
+}
+
+#if GLFW_HAS_WINDOW_ALPHA
+static void ImGui_ImplGlfw_SetWindowAlpha(ImGuiViewport* viewport, float alpha)
+{
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    glfwSetWindowOpacity(vd->Window, alpha);
+}
+#endif
+
+static void ImGui_ImplGlfw_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    if (bd->ClientApi == GlfwClientApi_OpenGL)
+        glfwMakeContextCurrent(vd->Window);
+}
+
+static void ImGui_ImplGlfw_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    if (bd->ClientApi == GlfwClientApi_OpenGL)
+    {
+        glfwMakeContextCurrent(vd->Window);
+        glfwSwapBuffers(vd->Window);
+    }
+}
+
+//--------------------------------------------------------------------------------------------------------
+// Vulkan support (the Vulkan renderer needs to call a platform-side support function to create the surface)
+//--------------------------------------------------------------------------------------------------------
+
+// Avoid including <vulkan.h> so we can build without it
+#if GLFW_HAS_VULKAN
+#ifndef VULKAN_H_
+#define VK_DEFINE_HANDLE(object) typedef struct object##_T* object;
+#if defined(__LP64__) || defined(_WIN64) || defined(__x86_64__) || defined(_M_X64) || defined(__ia64) || defined (_M_IA64) || defined(__aarch64__) || defined(__powerpc64__)
+#define VK_DEFINE_NON_DISPATCHABLE_HANDLE(object) typedef struct object##_T *object;
+#else
+#define VK_DEFINE_NON_DISPATCHABLE_HANDLE(object) typedef uint64_t object;
+#endif
+VK_DEFINE_HANDLE(VkInstance)
+VK_DEFINE_NON_DISPATCHABLE_HANDLE(VkSurfaceKHR)
+struct VkAllocationCallbacks;
+enum VkResult { VK_RESULT_MAX_ENUM = 0x7FFFFFFF };
+#endif // VULKAN_H_
+extern "C" { extern GLFWAPI VkResult glfwCreateWindowSurface(VkInstance instance, GLFWwindow* window, const VkAllocationCallbacks* allocator, VkSurfaceKHR* surface); }
+static int ImGui_ImplGlfw_CreateVkSurface(ImGuiViewport* viewport, ImU64 vk_instance, const void* vk_allocator, ImU64* out_vk_surface)
+{
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData;
+    IM_UNUSED(bd);
+    IM_ASSERT(bd->ClientApi == GlfwClientApi_Vulkan);
+    VkResult err = glfwCreateWindowSurface((VkInstance)vk_instance, vd->Window, (const VkAllocationCallbacks*)vk_allocator, (VkSurfaceKHR*)out_vk_surface);
+    return (int)err;
+}
+#endif // GLFW_HAS_VULKAN
+
+static void ImGui_ImplGlfw_InitMultiViewportSupport()
+{
+    // Register platform interface (will be coupled with a renderer interface)
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Platform_CreateWindow = ImGui_ImplGlfw_CreateWindow;
+    platform_io.Platform_DestroyWindow = ImGui_ImplGlfw_DestroyWindow;
+    platform_io.Platform_ShowWindow = ImGui_ImplGlfw_ShowWindow;
+    platform_io.Platform_SetWindowPos = ImGui_ImplGlfw_SetWindowPos;
+    platform_io.Platform_GetWindowPos = ImGui_ImplGlfw_GetWindowPos;
+    platform_io.Platform_SetWindowSize = ImGui_ImplGlfw_SetWindowSize;
+    platform_io.Platform_GetWindowSize = ImGui_ImplGlfw_GetWindowSize;
+    platform_io.Platform_GetWindowFramebufferScale = ImGui_ImplGlfw_GetWindowFramebufferScale;
+    platform_io.Platform_SetWindowFocus = ImGui_ImplGlfw_SetWindowFocus;
+    platform_io.Platform_GetWindowFocus = ImGui_ImplGlfw_GetWindowFocus;
+    platform_io.Platform_GetWindowMinimized = ImGui_ImplGlfw_GetWindowMinimized;
+    platform_io.Platform_SetWindowTitle = ImGui_ImplGlfw_SetWindowTitle;
+    platform_io.Platform_RenderWindow = ImGui_ImplGlfw_RenderWindow;
+    platform_io.Platform_SwapBuffers = ImGui_ImplGlfw_SwapBuffers;
+#if GLFW_HAS_WINDOW_ALPHA
+    platform_io.Platform_SetWindowAlpha = ImGui_ImplGlfw_SetWindowAlpha;
+#endif
+#if GLFW_HAS_VULKAN
+    platform_io.Platform_CreateVkSurface = ImGui_ImplGlfw_CreateVkSurface;
+#endif
+
+    // Register main window handle (which is owned by the main application, not by us)
+    // This is mostly for simplicity and consistency, so that our code (e.g. mouse handling etc.) can use same logic for main and secondary viewports.
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGui_ImplGlfw_ViewportData* vd = IM_NEW(ImGui_ImplGlfw_ViewportData)();
+    vd->Window = bd->Window;
+    vd->WindowOwned = false;
+    main_viewport->PlatformUserData = vd;
+    main_viewport->PlatformHandle = (void*)bd->Window;
+}
+
+static void ImGui_ImplGlfw_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
+//-----------------------------------------------------------------------------
+
+// WndProc hook (declared here because we will need access to ImGui_ImplGlfw_ViewportData)
+#ifdef _WIN32
+static ImGuiMouseSource GetMouseSourceFromMessageExtraInfo()
+{
+    LPARAM extra_info = ::GetMessageExtraInfo();
+    if ((extra_info & 0xFFFFFF80) == 0xFF515700)
+        return ImGuiMouseSource_Pen;
+    if ((extra_info & 0xFFFFFF80) == 0xFF515780)
+        return ImGuiMouseSource_TouchScreen;
+    return ImGuiMouseSource_Mouse;
+}
+static LRESULT CALLBACK ImGui_ImplGlfw_WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
+{
+    ImGui_ImplGlfw_Data* bd = (ImGui_ImplGlfw_Data*)::GetPropA(hWnd, "IMGUI_BACKEND_DATA");
+    ImGuiIO& io = ImGui::GetIO(bd->Context);
+
+    WNDPROC prev_wndproc = bd->PrevWndProc;
+    ImGuiViewport* viewport = (ImGuiViewport*)::GetPropA(hWnd, "IMGUI_VIEWPORT");
+    if (viewport != NULL)
+        if (ImGui_ImplGlfw_ViewportData* vd = (ImGui_ImplGlfw_ViewportData*)viewport->PlatformUserData)
+            prev_wndproc = vd->PrevWndProc;
+
+    switch (msg)
+    {
+        // GLFW doesn't allow to distinguish Mouse vs TouchScreen vs Pen.
+        // Add support for Win32 (based on imgui_impl_win32), because we rely on _TouchScreen info to trickle inputs differently.
+    case WM_MOUSEMOVE: case WM_NCMOUSEMOVE:
+    case WM_LBUTTONDOWN: case WM_LBUTTONDBLCLK: case WM_LBUTTONUP:
+    case WM_RBUTTONDOWN: case WM_RBUTTONDBLCLK: case WM_RBUTTONUP:
+    case WM_MBUTTONDOWN: case WM_MBUTTONDBLCLK: case WM_MBUTTONUP:
+    case WM_XBUTTONDOWN: case WM_XBUTTONDBLCLK: case WM_XBUTTONUP:
+        io.AddMouseSourceEvent(GetMouseSourceFromMessageExtraInfo());
+        break;
+
+        // We have submitted https://github.com/glfw/glfw/pull/1568 to allow GLFW to support "transparent inputs".
+        // In the meanwhile we implement custom per-platform workarounds here (FIXME-VIEWPORT: Implement same work-around for Linux/OSX!)
+#if !GLFW_HAS_MOUSE_PASSTHROUGH && GLFW_HAS_WINDOW_HOVERED
+    case WM_NCHITTEST:
+    {
+        // Let mouse pass-through the window. This will allow the backend to call io.AddMouseViewportEvent() properly (which is OPTIONAL).
+        // The ImGuiViewportFlags_NoInputs flag is set while dragging a viewport, as want to detect the window behind the one we are dragging.
+        // If you cannot easily access those viewport flags from your windowing/event code: you may manually synchronize its state e.g. in
+        // your main loop after calling UpdatePlatformWindows(). Iterate all viewports/platform windows and pass the flag to your windowing system.
+        if (viewport && (viewport->Flags & ImGuiViewportFlags_NoInputs))
+            return HTTRANSPARENT;
+        break;
+    }
+#endif
+    default: break;
+    }
+    return ::CallWindowProcW(prev_wndproc, hWnd, msg, wParam, lParam);
+}
+#endif // #ifdef _WIN32
+
 //-----------------------------------------------------------------------------
 
 #if defined(__clang__)

diff --git a/backends/imgui_impl_glfw.h b/backends/imgui_impl_glfw.h
index 7dc8cb5..c3dcfa7 100644
--- a/backends/imgui_impl_glfw.h
+++ b/backends/imgui_impl_glfw.h

@@ -9,10 +9,12 @@
 //  [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy GLFW_KEY_* values are obsolete since 1.87 and not supported since 1.91.5]
 //  [X] Platform: Gamepad support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
 //  [X] Platform: Mouse cursor shape and visibility (ImGuiBackendFlags_HasMouseCursors) with GLFW 3.1+. Resizing cursors requires GLFW 3.4+! Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 //  [X] Multiple Dear ImGui contexts support.
 // Missing features or Issues:
 //  [ ] Platform: Touch events are only correctly identified as Touch on Windows. This create issues with some interactions. GLFW doesn't provide a way to identify touch inputs from mouse inputs, we cannot call io.AddMouseSourceEvent() to identify the source. We provide a Windows-specific workaround.
 //  [ ] Platform: Missing ImGuiMouseCursor_Wait and ImGuiMouseCursor_Progress cursors.
+//  [ ] Platform: Multi-viewport: Missing ImGuiBackendFlags_HasParentViewport support. The viewport->ParentViewportID field is ignored, and therefore io.ConfigViewportsNoDefaultParent has no effect either.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_glut.cpp b/backends/imgui_impl_glut.cpp
index a68f9db..bb78a9b 100644
--- a/backends/imgui_impl_glut.cpp
+++ b/backends/imgui_impl_glut.cpp

@@ -13,6 +13,7 @@
 //  [ ] Platform: Missing mouse cursor shape/visibility support.
 //  [ ] Platform: Missing clipboard support (not supported by Glut).
 //  [ ] Platform: Missing gamepad support.
+//  [ ] Platform: Missing multi-viewport support (multiple windows).
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_glut.h b/backends/imgui_impl_glut.h
index 20e77db..d5d01a2 100644
--- a/backends/imgui_impl_glut.h
+++ b/backends/imgui_impl_glut.h

@@ -13,6 +13,7 @@
 //  [ ] Platform: Missing mouse cursor shape/visibility support.
 //  [ ] Platform: Missing clipboard support (not supported by Glut).
 //  [ ] Platform: Missing gamepad support.
+//  [ ] Platform: Missing multi-viewport support (multiple windows).
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_metal.h b/backends/imgui_impl_metal.h
index 8af2c8b..586b0d3 100644
--- a/backends/imgui_impl_metal.h
+++ b/backends/imgui_impl_metal.h

@@ -5,6 +5,7 @@
 //  [X] Renderer: User texture binding. Use 'MTLTexture' as texture identifier. Read the FAQ about ImTextureID/ImTextureRef!
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_metal.mm b/backends/imgui_impl_metal.mm
index 96695d9..d44e65b 100644
--- a/backends/imgui_impl_metal.mm
+++ b/backends/imgui_impl_metal.mm

@@ -5,6 +5,7 @@
 //  [X] Renderer: User texture binding. Use 'MTLTexture' as texture identifier. Read the FAQ about ImTextureID/ImTextureRef!
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -16,6 +17,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-XX-XX: Metal: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-11: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas. Removed ImGui_ImplMetal_CreateFontsTexture() and ImGui_ImplMetal_DestroyFontsTexture().
 //  2025-02-03: Metal: Crash fix. (#8367)
@@ -43,6 +45,12 @@
 #import <time.h>
 #import <Metal/Metal.h>
 
+// Forward Declarations
+static void ImGui_ImplMetal_InitMultiViewportSupport();
+static void ImGui_ImplMetal_ShutdownMultiViewportSupport();
+static void ImGui_ImplMetal_CreateDeviceObjectsForPlatformWindows();
+static void ImGui_ImplMetal_InvalidateDeviceObjectsForPlatformWindows();
+
 #pragma mark - Support classes
 
 // A wrapper around a MTLBuffer object that knows the last time it was reused
@@ -137,10 +145,13 @@
     io.BackendRendererName = "imgui_impl_metal";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
     io.BackendFlags |= ImGuiBackendFlags_RendererHasTextures;   // We can honor ImGuiPlatformIO::Textures[] requests during render.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)
 
     bd->SharedMetalContext = [[MetalContext alloc] init];
     bd->SharedMetalContext.device = device;
 
+    ImGui_ImplMetal_InitMultiViewportSupport();
+
     return true;
 }
 
@@ -152,12 +163,13 @@
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
+    ImGui_ImplMetal_ShutdownMultiViewportSupport();
     ImGui_ImplMetal_DestroyDeviceObjects();
     ImGui_ImplMetal_DestroyBackendData();
 
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures);
+    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
     platform_io.ClearRendererHandlers();
 }
 
@@ -410,6 +422,7 @@
     depthStencilDescriptor.depthWriteEnabled = NO;
     depthStencilDescriptor.depthCompareFunction = MTLCompareFunctionAlways;
     bd->SharedMetalContext.depthStencilState = [device newDepthStencilStateWithDescriptor:depthStencilDescriptor];
+    ImGui_ImplMetal_CreateDeviceObjectsForPlatformWindows();
 #ifdef IMGUI_IMPL_METAL_CPP
     [depthStencilDescriptor release];
 #endif
@@ -426,9 +439,154 @@
         if (tex->RefCount == 1)
             ImGui_ImplMetal_DestroyTexture(tex);
 
+    ImGui_ImplMetal_InvalidateDeviceObjectsForPlatformWindows();
     [bd->SharedMetalContext.renderPipelineStateCache removeAllObjects];
 }
 
+#pragma mark - Multi-viewport support
+
+#import <QuartzCore/CAMetalLayer.h>
+
+#if TARGET_OS_OSX
+#import <Cocoa/Cocoa.h>
+#endif
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the back-end to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+struct ImGuiViewportDataMetal
+{
+    CAMetalLayer*               MetalLayer;
+    id<MTLCommandQueue>         CommandQueue;
+    MTLRenderPassDescriptor*    RenderPassDescriptor;
+    void*                       Handle = nullptr;
+    bool                        FirstFrame = true;
+};
+
+static void ImGui_ImplMetal_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplMetal_Data* bd = ImGui_ImplMetal_GetBackendData();
+    ImGuiViewportDataMetal* data = IM_NEW(ImGuiViewportDataMetal)();
+    viewport->RendererUserData = data;
+
+    // PlatformHandleRaw should always be a NSWindow*, whereas PlatformHandle might be a higher-level handle (e.g. GLFWWindow*, SDL_Window*).
+    // Some back-ends will leave PlatformHandleRaw == 0, in which case we assume PlatformHandle will contain the NSWindow*.
+    void* handle = viewport->PlatformHandleRaw ? viewport->PlatformHandleRaw : viewport->PlatformHandle;
+    IM_ASSERT(handle != nullptr);
+
+    id<MTLDevice> device = bd->SharedMetalContext.device;
+    CAMetalLayer* layer = [CAMetalLayer layer];
+    layer.device = device;
+    layer.framebufferOnly = YES;
+    layer.pixelFormat = bd->SharedMetalContext.framebufferDescriptor.colorPixelFormat;
+#if TARGET_OS_OSX
+    NSWindow* window = (__bridge NSWindow*)handle;
+    NSView* view = window.contentView;
+    view.layer = layer;
+    view.wantsLayer = YES;
+#endif
+    data->MetalLayer = layer;
+    data->CommandQueue = [device newCommandQueue];
+    data->RenderPassDescriptor = [[MTLRenderPassDescriptor alloc] init];
+    data->Handle = handle;
+}
+
+static void ImGui_ImplMetal_DestroyWindow(ImGuiViewport* viewport)
+{
+    // The main viewport (owned by the application) will always have RendererUserData == 0 since we didn't create the data for it.
+    if (ImGuiViewportDataMetal* data = (ImGuiViewportDataMetal*)viewport->RendererUserData)
+        IM_DELETE(data);
+    viewport->RendererUserData = nullptr;
+}
+
+inline static CGSize MakeScaledSize(CGSize size, CGFloat scale)
+{
+    return CGSizeMake(size.width * scale, size.height * scale);
+}
+
+static void ImGui_ImplMetal_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGuiViewportDataMetal* data = (ImGuiViewportDataMetal*)viewport->RendererUserData;
+    data->MetalLayer.drawableSize = MakeScaledSize(CGSizeMake(size.x, size.y), viewport->DpiScale);
+}
+
+static void ImGui_ImplMetal_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGuiViewportDataMetal* data = (ImGuiViewportDataMetal*)viewport->RendererUserData;
+
+#if TARGET_OS_OSX
+    void* handle = viewport->PlatformHandleRaw ? viewport->PlatformHandleRaw : viewport->PlatformHandle;
+    NSWindow* window = (__bridge NSWindow*)handle;
+
+    // Always render the first frame, regardless of occlusionState, to avoid an initial flicker
+    if ((window.occlusionState & NSWindowOcclusionStateVisible) == 0 && !data->FirstFrame)
+    {
+        // Do not render windows which are completely occluded. Calling -[CAMetalLayer nextDrawable] will hang for
+        // approximately 1 second if the Metal layer is completely occluded.
+        return;
+    }
+    data->FirstFrame = false;
+
+    float fb_scale = (float)window.backingScaleFactor;
+    if (data->MetalLayer.contentsScale != fb_scale)
+    {
+        data->MetalLayer.contentsScale = fb_scale;
+        data->MetalLayer.drawableSize = MakeScaledSize(window.frame.size, fb_scale);
+    }
+#endif
+
+    id <CAMetalDrawable> drawable = [data->MetalLayer nextDrawable];
+    if (drawable == nil)
+        return;
+
+    MTLRenderPassDescriptor* renderPassDescriptor = data->RenderPassDescriptor;
+    renderPassDescriptor.colorAttachments[0].texture = drawable.texture;
+    renderPassDescriptor.colorAttachments[0].clearColor = MTLClearColorMake(0, 0, 0, 0);
+    if ((viewport->Flags & ImGuiViewportFlags_NoRendererClear) == 0)
+        renderPassDescriptor.colorAttachments[0].loadAction = MTLLoadActionClear;
+
+    id <MTLCommandBuffer> commandBuffer = [data->CommandQueue commandBuffer];
+    id <MTLRenderCommandEncoder> renderEncoder = [commandBuffer renderCommandEncoderWithDescriptor:renderPassDescriptor];
+    ImGui_ImplMetal_RenderDrawData(viewport->DrawData, commandBuffer, renderEncoder);
+    [renderEncoder endEncoding];
+
+    [commandBuffer presentDrawable:drawable];
+    [commandBuffer commit];
+}
+
+static void ImGui_ImplMetal_InitMultiViewportSupport()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_CreateWindow = ImGui_ImplMetal_CreateWindow;
+    platform_io.Renderer_DestroyWindow = ImGui_ImplMetal_DestroyWindow;
+    platform_io.Renderer_SetWindowSize = ImGui_ImplMetal_SetWindowSize;
+    platform_io.Renderer_RenderWindow = ImGui_ImplMetal_RenderWindow;
+}
+
+static void ImGui_ImplMetal_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
+static void ImGui_ImplMetal_CreateDeviceObjectsForPlatformWindows()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int i = 1; i < platform_io.Viewports.Size; i++)
+        if (!platform_io.Viewports[i]->RendererUserData)
+            ImGui_ImplMetal_CreateWindow(platform_io.Viewports[i]);
+}
+
+static void ImGui_ImplMetal_InvalidateDeviceObjectsForPlatformWindows()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int i = 1; i < platform_io.Viewports.Size; i++)
+        if (platform_io.Viewports[i]->RendererUserData)
+            ImGui_ImplMetal_DestroyWindow(platform_io.Viewports[i]);
+}
+
 #pragma mark - MetalBuffer implementation
 
 @implementation MetalBuffer

diff --git a/backends/imgui_impl_opengl2.cpp b/backends/imgui_impl_opengl2.cpp
index af5618f..236b89f 100644
--- a/backends/imgui_impl_opengl2.cpp
+++ b/backends/imgui_impl_opengl2.cpp

@@ -4,6 +4,7 @@
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'GLuint' OpenGL texture as texture identifier. Read the FAQ about ImTextureID/ImTextureRef!
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 // Missing features or Issues:
 //  [ ] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 
@@ -25,6 +26,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-07-15: OpenGL: Set GL_UNPACK_ALIGNMENT to 1 before updating textures. (#8802)
 //  2025-06-11: OpenGL: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas. Removed ImGui_ImplOpenGL2_CreateFontsTexture() and ImGui_ImplOpenGL2_DestroyFontsTexture().
@@ -95,6 +97,10 @@
     return ImGui::GetCurrentContext() ? (ImGui_ImplOpenGL2_Data*)ImGui::GetIO().BackendRendererUserData : nullptr;
 }
 
+// Forward Declarations
+static void ImGui_ImplOpenGL2_InitMultiViewportSupport();
+static void ImGui_ImplOpenGL2_ShutdownMultiViewportSupport();
+
 // Functions
 bool    ImGui_ImplOpenGL2_Init()
 {
@@ -107,6 +113,9 @@
     io.BackendRendererUserData = (void*)bd;
     io.BackendRendererName = "imgui_impl_opengl2";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasTextures;       // We can honor ImGuiPlatformIO::Textures[] requests during render.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;      // We can create multi-viewports on the Renderer side (optional)
+
+    ImGui_ImplOpenGL2_InitMultiViewportSupport();
 
     return true;
 }
@@ -118,11 +127,12 @@
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
+    ImGui_ImplOpenGL2_ShutdownMultiViewportSupport();
     ImGui_ImplOpenGL2_DestroyDeviceObjects();
 
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasTextures);
+    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
     platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
@@ -343,6 +353,35 @@
         }
 }
 
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+static void ImGui_ImplOpenGL2_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
+    {
+        ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+        glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+        glClear(GL_COLOR_BUFFER_BIT);
+    }
+    ImGui_ImplOpenGL2_RenderDrawData(viewport->DrawData);
+}
+
+static void ImGui_ImplOpenGL2_InitMultiViewportSupport()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_RenderWindow = ImGui_ImplOpenGL2_RenderWindow;
+}
+
+static void ImGui_ImplOpenGL2_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
 //-----------------------------------------------------------------------------
 
 #if defined(__clang__)

diff --git a/backends/imgui_impl_opengl2.h b/backends/imgui_impl_opengl2.h
index 65b0fe0..cd18594 100644
--- a/backends/imgui_impl_opengl2.h
+++ b/backends/imgui_impl_opengl2.h

@@ -4,6 +4,7 @@
 // Implemented features:
 //  [X] Renderer: User texture binding. Use 'GLuint' OpenGL texture as texture identifier. Read the FAQ about ImTextureID/ImTextureRef!
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 // Missing features or Issues:
 //  [ ] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 

diff --git a/backends/imgui_impl_opengl3.cpp b/backends/imgui_impl_opengl3.cpp
index 6348b01..b515ce0 100644
--- a/backends/imgui_impl_opengl3.cpp
+++ b/backends/imgui_impl_opengl3.cpp

@@ -7,6 +7,7 @@
 //  [X] Renderer: User texture binding. Use 'GLuint' OpenGL texture as texture identifier. Read the FAQ about ImTextureID/ImTextureRef!
 //  [x] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset) [Desktop OpenGL only!]
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // About WebGL/ES:
 // - You need to '#define IMGUI_IMPL_OPENGL_ES2' or '#define IMGUI_IMPL_OPENGL_ES3' to use WebGL or OpenGL ES.
@@ -23,6 +24,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2025-12-11: OpenGL: Fixed embedded loader multiple init/shutdown cycles broken on some platforms. (#8792, #9112)
 //  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-07-22: OpenGL: Add and call embedded loader shutdown during ImGui_ImplOpenGL3_Shutdown() to facilitate multiple init/shutdown cycles in same process. (#8792)
@@ -263,6 +265,10 @@
     return ImGui::GetCurrentContext() ? (ImGui_ImplOpenGL3_Data*)ImGui::GetIO().BackendRendererUserData : nullptr;
 }
 
+// Forward Declarations
+static void ImGui_ImplOpenGL3_InitMultiViewportSupport();
+static void ImGui_ImplOpenGL3_ShutdownMultiViewportSupport();
+
 // OpenGL vertex attribute state (for ES 1.0 and ES 2.0 only)
 #ifndef IMGUI_IMPL_OPENGL_USE_VERTEX_ARRAY
 struct ImGui_ImplOpenGL3_VtxAttribState
@@ -377,6 +383,7 @@
         io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
 #endif
     io.BackendFlags |= ImGuiBackendFlags_RendererHasTextures;       // We can honor ImGuiPlatformIO::Textures[] requests during render.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;      // We can create multi-viewports on the Renderer side (optional)
 
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
     platform_io.Renderer_TextureMaxWidth = platform_io.Renderer_TextureMaxHeight = (int)bd->MaxTextureSize;
@@ -423,6 +430,8 @@
     }
 #endif
 
+    ImGui_ImplOpenGL3_InitMultiViewportSupport();
+
     return true;
 }
 
@@ -433,11 +442,12 @@
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
+    ImGui_ImplOpenGL3_ShutdownMultiViewportSupport();
     ImGui_ImplOpenGL3_DestroyDeviceObjects();
 
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures);
+    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
     platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 
@@ -1054,6 +1064,34 @@
             ImGui_ImplOpenGL3_DestroyTexture(tex);
 }
 
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+static void ImGui_ImplOpenGL3_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    if (!(viewport->Flags & ImGuiViewportFlags_NoRendererClear))
+    {
+        ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+        glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+        glClear(GL_COLOR_BUFFER_BIT);
+    }
+    ImGui_ImplOpenGL3_RenderDrawData(viewport->DrawData);
+}
+
+static void ImGui_ImplOpenGL3_InitMultiViewportSupport()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_RenderWindow = ImGui_ImplOpenGL3_RenderWindow;
+}
+
+static void ImGui_ImplOpenGL3_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
 //-----------------------------------------------------------------------------
 
 #if defined(__GNUC__)

diff --git a/backends/imgui_impl_opengl3.h b/backends/imgui_impl_opengl3.h
index aabe04b..7855c43 100644
--- a/backends/imgui_impl_opengl3.h
+++ b/backends/imgui_impl_opengl3.h

@@ -7,6 +7,7 @@
 //  [X] Renderer: User texture binding. Use 'GLuint' OpenGL texture as texture identifier. Read the FAQ about ImTextureID/ImTextureRef!
 //  [x] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset) [Desktop OpenGL only!]
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // About WebGL/ES:
 // - You need to '#define IMGUI_IMPL_OPENGL_ES2' or '#define IMGUI_IMPL_OPENGL_ES3' to use WebGL or OpenGL ES.

diff --git a/backends/imgui_impl_osx.h b/backends/imgui_impl_osx.h
index ea2b4f4..d944f3e 100644
--- a/backends/imgui_impl_osx.h
+++ b/backends/imgui_impl_osx.h

@@ -10,6 +10,10 @@
 //  [X] Platform: Gamepad support.
 //  [X] Platform: Mouse cursor shape and visibility (ImGuiBackendFlags_HasMouseCursors). Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
 //  [X] Platform: IME support.
+//  [x] Platform: Multi-viewport / platform windows.
+// Missing features or Issues:
+//  [ ] Platform: Multi-viewport: Window size not correctly reported when enabling io.ConfigViewportsNoDecoration
+//  [ ] Platform: Multi-viewport: Missing ImGuiBackendFlags_HasParentViewport support. The viewport->ParentViewportID field is ignored, and therefore io.ConfigViewportsNoDefaultParent has no effect either.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_osx.mm b/backends/imgui_impl_osx.mm
index 0dfdd8e..c60aa4c 100644
--- a/backends/imgui_impl_osx.mm
+++ b/backends/imgui_impl_osx.mm

@@ -10,6 +10,10 @@
 //  [X] Platform: Gamepad support.
 //  [X] Platform: Mouse cursor shape and visibility (ImGuiBackendFlags_HasMouseCursors). Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
 //  [X] Platform: IME support.
+//  [x] Platform: Multi-viewport / platform windows.
+// Missing features or Issues:
+//  [ ] Platform: Multi-viewport: Window size not correctly reported when enabling io.ConfigViewportsNoDecoration
+//  [ ] Platform: Multi-viewport: Missing ImGuiBackendFlags_HasParentViewport support. The viewport->ParentViewportID field is ignored, and therefore io.ConfigViewportsNoDefaultParent has no effect either.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -29,9 +33,12 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-XX-XX: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2025-09-18: Call platform_io.ClearPlatformHandlers() on shutdown.
+//  2025-07-08: [Docking] Fixed multi-viewport handling broken on 2025-06-02. (#8644, #8777)
 //  2025-06-27: Added ImGuiMouseCursor_Wait and ImGuiMouseCursor_Progress mouse cursor support.
 //  2025-06-12: ImGui_ImplOSX_HandleEvent() only process event for window containing our view. (#8644)
+//  2025-05-15: [Docking] Add Platform_GetWindowFramebufferScale() handler, to allow varying Retina display density on multiple monitors.
 //  2025-03-21: Fill gamepad inputs and set ImGuiBackendFlags_HasGamepad regardless of ImGuiConfigFlags_NavEnableGamepad being set.
 //  2025-01-20: Removed notification observer when shutting down. (#8331)
 //  2024-08-22: moved some OS/backend related function pointers from ImGuiIO to ImGuiPlatformIO:
@@ -101,6 +108,9 @@
 static inline CFTimeInterval    GetMachAbsoluteTimeInSeconds()      { return (CFTimeInterval)(double)(clock_gettime_nsec_np(CLOCK_UPTIME_RAW) / 1e9); }
 
 // Forward Declarations
+static void ImGui_ImplOSX_InitMultiViewportSupport();
+static void ImGui_ImplOSX_ShutdownMultiViewportSupport();
+static void ImGui_ImplOSX_UpdateMonitors();
 static void ImGui_ImplOSX_AddTrackingArea(NSView* _Nonnull view);
 static bool ImGui_ImplOSX_HandleEvent(NSEvent* event, NSView* view);
 
@@ -148,6 +158,20 @@
     NSWindow* window = view.window;
     if (!window)
         return;
+
+    ImGuiIO& io = ImGui::GetIO();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        NSRect frame = window.frame;
+        NSRect contentRect = window.contentLayoutRect;
+        if (window.styleMask & NSWindowStyleMaskFullSizeContentView) // No title bar windows should be considered.
+            contentRect = frame;
+
+        NSRect firstScreenFrame = NSScreen.screens[0].frame;
+        _imeRect = NSMakeRect(_posX, _posY, 0, 0);
+        _imeRect.origin.y = firstScreenFrame.size.height - _imeRect.size.height - _imeRect.origin.y; // Opposite of ConvertNSRect()
+    }
+    else
     {
         NSRect contentRect = [window contentRectForFrameRect:window.frame];
         NSRect rect = NSMakeRect(_posX, contentRect.size.height - _posY, 0, 0);
@@ -247,6 +271,7 @@
 
 - (void)onApplicationBecomeActive:(NSNotification*)aNotification;
 - (void)onApplicationBecomeInactive:(NSNotification*)aNotification;
+- (void)displaysDidChange:(NSNotification*)aNotification;
 
 @end
 
@@ -264,6 +289,11 @@
     io.AddFocusEvent(false);
 }
 
+- (void)displaysDidChange:(NSNotification*)aNotification
+{
+    ImGui_ImplOSX_UpdateMonitors();
+}
+
 @end
 
 // Functions
@@ -418,11 +448,15 @@
     io.BackendPlatformName = "imgui_impl_osx";
     io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;           // We can honor GetMouseCursor() values (optional)
     //io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;          // We can honor io.WantSetMousePos requests (optional, rarely used)
+    io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports;      // We can create multi-viewports on the Platform side (optional)
+    //io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport; // We can call io.AddMouseViewportEvent() with correct data (optional)
 
     bd->Observer = [ImGuiObserver new];
     bd->Window = view.window ?: NSApp.orderedWindows.firstObject;
     ImGuiViewport* main_viewport = ImGui::GetMainViewport();
     main_viewport->PlatformHandle = main_viewport->PlatformHandleRaw = (__bridge_retained void*)bd->Window;
+    ImGui_ImplOSX_UpdateMonitors();
+    ImGui_ImplOSX_InitMultiViewportSupport();
 
     // Load cursors. Some of them are undocumented.
     bd->MouseCursorHidden = false;
@@ -514,14 +548,14 @@
         bd->Monitor = nullptr;
     }
 
+    ImGui_ImplOSX_ShutdownMultiViewportSupport();
     ImGui_ImplOSX_DestroyBackendData();
-
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     io.BackendPlatformName = nullptr;
     io.BackendPlatformUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasGamepad);
+    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasGamepad | ImGuiBackendFlags_PlatformHasViewports);
     platform_io.ClearPlatformHandlers();
 }
 
@@ -672,10 +706,10 @@
 static bool ImGui_ImplOSX_HandleEvent(NSEvent* event, NSView* view)
 {
     // Only process events from the window containing ImGui view
-    if (event.window != view.window)
+    if (!ImGui::FindViewportByPlatformHandle((__bridge void*)event.window))
         return false;
-    ImGuiIO& io = ImGui::GetIO();
 
+    ImGuiIO& io = ImGui::GetIO();
     if (event.type == NSEventTypeLeftMouseDown || event.type == NSEventTypeRightMouseDown || event.type == NSEventTypeOtherMouseDown)
     {
         int button = (int)[event buttonNumber];
@@ -700,14 +734,23 @@
 
     if (event.type == NSEventTypeMouseMoved || event.type == NSEventTypeLeftMouseDragged || event.type == NSEventTypeRightMouseDragged || event.type == NSEventTypeOtherMouseDragged)
     {
-        NSPoint mousePoint = event.locationInWindow;
-        if (event.window == nil)
-            mousePoint = [[view window] convertPointFromScreen:mousePoint];
-        mousePoint = [view convertPoint:mousePoint fromView:nil];
-        if ([view isFlipped])
-            mousePoint = NSMakePoint(mousePoint.x, mousePoint.y);
+        NSPoint mousePoint;
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            mousePoint = NSEvent.mouseLocation;
+            mousePoint.y = CGDisplayPixelsHigh(kCGDirectMainDisplay) - mousePoint.y; // Normalize y coordinate to top-left of main display.
+        }
         else
-            mousePoint = NSMakePoint(mousePoint.x, view.bounds.size.height - mousePoint.y);
+        {
+            mousePoint = event.locationInWindow;
+            if (event.window == nil)
+                mousePoint = [[view window] convertPointFromScreen:mousePoint];
+            mousePoint = [view convertPoint:mousePoint fromView:nil]; // Convert to local coordinates of view
+            if ([view isFlipped])
+                mousePoint = NSMakePoint(mousePoint.x, mousePoint.y);
+            else
+                mousePoint = NSMakePoint(mousePoint.x, view.bounds.size.height - mousePoint.y);
+        }
         io.AddMouseSourceEvent(GetMouseSource(event));
         io.AddMousePosEvent((float)mousePoint.x, (float)mousePoint.y);
         return io.WantCaptureMouse;
@@ -833,6 +876,300 @@
     }];
 }
 
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the back-end to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+struct ImGui_ImplOSX_ViewportData
+{
+    NSWindow*        Window;
+    bool             WindowOwned;
+
+    ImGui_ImplOSX_ViewportData()  { WindowOwned = false; }
+    ~ImGui_ImplOSX_ViewportData() { IM_ASSERT(Window == nil); }
+};
+
+@interface ImGui_ImplOSX_Window: NSWindow
+@end
+
+@implementation ImGui_ImplOSX_Window
+
+- (BOOL)canBecomeKeyWindow
+{
+    return YES;
+}
+
+@end
+
+static void ConvertNSRect(NSRect* r)
+{
+    NSRect firstScreenFrame = NSScreen.screens[0].frame;
+    IM_ASSERT(firstScreenFrame.origin.x == 0 && firstScreenFrame.origin.y == 0);
+    r->origin.y = firstScreenFrame.size.height - r->origin.y - r->size.height;
+}
+
+static void ImGui_ImplOSX_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplOSX_Data* bd = ImGui_ImplOSX_GetBackendData();
+    ImGui_ImplOSX_ViewportData* vd = IM_NEW(ImGui_ImplOSX_ViewportData)();
+    viewport->PlatformUserData = vd;
+
+    NSScreen* screen = bd->Window.screen;
+    NSRect rect = NSMakeRect(viewport->Pos.x, viewport->Pos.y, viewport->Size.x, viewport->Size.y);
+    ConvertNSRect(&rect);
+
+    NSWindowStyleMask styleMask = 0;
+    if (viewport->Flags & ImGuiViewportFlags_NoDecoration)
+        styleMask |= NSWindowStyleMaskBorderless;
+    else
+        styleMask |= NSWindowStyleMaskTitled | NSWindowStyleMaskResizable | NSWindowStyleMaskClosable | NSWindowStyleMaskMiniaturizable;
+
+    NSWindow* window = [[ImGui_ImplOSX_Window alloc] initWithContentRect:rect
+                                                               styleMask:styleMask
+                                                                 backing:NSBackingStoreBuffered
+                                                                   defer:YES
+                                                                  screen:screen];
+    if (viewport->Flags & ImGuiViewportFlags_TopMost)
+        [window setLevel:NSFloatingWindowLevel];
+
+    window.title = @"Untitled";
+    window.opaque = YES;
+
+    KeyEventResponder* view = [[KeyEventResponder alloc] initWithFrame:rect];
+    if (floor(NSAppKitVersionNumber) > NSAppKitVersionNumber10_6 && ceil(NSAppKitVersionNumber) < NSAppKitVersionNumber10_15)
+        [view setWantsBestResolutionOpenGLSurface:YES];
+
+    window.contentView = view;
+
+    vd->Window = window;
+    vd->WindowOwned = true;
+    viewport->PlatformRequestResize = false;
+    viewport->PlatformHandle = viewport->PlatformHandleRaw = (__bridge_retained void*)window;
+}
+
+static void ImGui_ImplOSX_DestroyWindow(ImGuiViewport* viewport)
+{
+    if (ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)viewport->PlatformUserData)
+    {
+        NSWindow* window = vd->Window;
+        if (window != nil && vd->WindowOwned)
+        {
+            window.contentView = nil;
+            window.contentViewController = nil;
+            [window orderOut:nil];
+        }
+        vd->Window = nil;
+        IM_DELETE(vd);
+    }
+    viewport->PlatformUserData = viewport->PlatformHandle = viewport->PlatformHandleRaw = nullptr;
+}
+
+static void ImGui_ImplOSX_ShowWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Window != 0);
+
+    if (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing)
+        [vd->Window orderFront:nil];
+    else
+        [vd->Window makeKeyAndOrderFront:nil];
+
+    [vd->Window setIsVisible:YES];
+}
+
+static ImVec2 ImGui_ImplOSX_GetWindowPos(ImGuiViewport* viewport)
+{
+    ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Window != 0);
+
+    NSWindow* window = vd->Window;
+    NSRect frame = window.frame;
+    NSRect contentRect = window.contentLayoutRect;
+    if (window.styleMask & NSWindowStyleMaskFullSizeContentView) // No title bar windows should be considered.
+        contentRect = frame;
+
+    NSRect firstScreenFrame = NSScreen.screens[0].frame;
+    return ImVec2(frame.origin.x, firstScreenFrame.size.height - frame.origin.y - contentRect.size.height);
+}
+
+static void ImGui_ImplOSX_SetWindowPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Window != 0);
+
+    NSWindow* window = vd->Window;
+    NSSize size = window.frame.size;
+
+    NSRect r = NSMakeRect(pos.x, pos.y, size.width, size.height);
+    ConvertNSRect(&r);
+    [window setFrameOrigin:r.origin];
+}
+
+static ImVec2 ImGui_ImplOSX_GetWindowSize(ImGuiViewport* viewport)
+{
+    ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Window != 0);
+
+    NSWindow* window = vd->Window;
+    NSSize size = window.contentLayoutRect.size;
+    return ImVec2(size.width, size.height);
+}
+
+static void ImGui_ImplOSX_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Window != 0);
+
+    NSWindow* window = vd->Window;
+    NSRect rect = window.frame;
+    rect.origin.y -= (size.y - rect.size.height);
+    rect.size.width = size.x;
+    rect.size.height = size.y;
+    [window setFrame:rect display:YES];
+}
+
+static ImVec2 ImGui_ImplOSX_GetWindowFramebufferScale(ImGuiViewport* viewport)
+{
+    ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)viewport->PlatformUserData;
+    NSWindow* window = vd->Window;
+    const float fb_scale = (float)[window backingScaleFactor];
+    return ImVec2(fb_scale, fb_scale);
+}
+
+static void ImGui_ImplOSX_SetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGui_ImplOSX_Data* bd = ImGui_ImplOSX_GetBackendData();
+    ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Window != 0);
+    [vd->Window makeKeyAndOrderFront:bd->Window];
+}
+
+static bool ImGui_ImplOSX_GetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Window != 0);
+
+    return vd->Window.isKeyWindow;
+}
+
+static bool ImGui_ImplOSX_GetWindowMinimized(ImGuiViewport* viewport)
+{
+    ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Window != 0);
+
+    return vd->Window.isMiniaturized;
+}
+
+static void ImGui_ImplOSX_SetWindowTitle(ImGuiViewport* viewport, const char* title)
+{
+    ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Window != 0);
+
+    vd->Window.title = [NSString stringWithUTF8String:title];
+}
+
+static void ImGui_ImplOSX_SetWindowAlpha(ImGuiViewport* viewport, float alpha)
+{
+    ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Window != 0);
+    IM_ASSERT(alpha >= 0.0f && alpha <= 1.0f);
+
+    vd->Window.alphaValue = alpha;
+}
+
+static float ImGui_ImplOSX_GetWindowDpiScale(ImGuiViewport* viewport)
+{
+    ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Window != 0);
+
+    return vd->Window.backingScaleFactor;
+}
+
+static void ImGui_ImplOSX_UpdateMonitors()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Monitors.resize(0);
+
+    NSRect firstScreenFrame = NSScreen.screens[0].frame;
+    IM_ASSERT(firstScreenFrame.origin.x == 0 && firstScreenFrame.origin.y == 0);
+
+    for (NSScreen* screen in NSScreen.screens)
+    {
+        NSRect frame = screen.frame;
+        NSRect visibleFrame = screen.visibleFrame;
+        ConvertNSRect(&frame);
+        ConvertNSRect(&visibleFrame);
+
+        ImGuiPlatformMonitor imgui_monitor;
+        imgui_monitor.MainPos = ImVec2(frame.origin.x, frame.origin.y);
+        imgui_monitor.MainSize = ImVec2(frame.size.width, frame.size.height);
+        imgui_monitor.WorkPos = ImVec2(visibleFrame.origin.x, visibleFrame.origin.y);
+        imgui_monitor.WorkSize = ImVec2(visibleFrame.size.width, visibleFrame.size.height);
+        imgui_monitor.DpiScale = screen.backingScaleFactor;
+        imgui_monitor.PlatformHandle = (__bridge_retained void*)screen;
+
+        platform_io.Monitors.push_back(imgui_monitor);
+    }
+}
+
+static void ImGui_ImplOSX_InitMultiViewportSupport()
+{
+    ImGui_ImplOSX_Data* bd = ImGui_ImplOSX_GetBackendData();
+
+    // Register platform interface (will be coupled with a renderer interface)
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Platform_CreateWindow = ImGui_ImplOSX_CreateWindow;
+    platform_io.Platform_DestroyWindow = ImGui_ImplOSX_DestroyWindow;
+    platform_io.Platform_ShowWindow = ImGui_ImplOSX_ShowWindow;
+    platform_io.Platform_SetWindowPos = ImGui_ImplOSX_SetWindowPos;
+    platform_io.Platform_GetWindowPos = ImGui_ImplOSX_GetWindowPos;
+    platform_io.Platform_SetWindowSize = ImGui_ImplOSX_SetWindowSize;
+    platform_io.Platform_GetWindowSize = ImGui_ImplOSX_GetWindowSize;
+    platform_io.Platform_GetWindowFramebufferScale = ImGui_ImplOSX_GetWindowFramebufferScale;
+    platform_io.Platform_SetWindowFocus = ImGui_ImplOSX_SetWindowFocus;
+    platform_io.Platform_GetWindowFocus = ImGui_ImplOSX_GetWindowFocus;
+    platform_io.Platform_GetWindowMinimized = ImGui_ImplOSX_GetWindowMinimized;
+    platform_io.Platform_SetWindowTitle = ImGui_ImplOSX_SetWindowTitle;
+    platform_io.Platform_SetWindowAlpha = ImGui_ImplOSX_SetWindowAlpha;
+    platform_io.Platform_GetWindowDpiScale = ImGui_ImplOSX_GetWindowDpiScale; // FIXME-DPI
+
+    // Register main window handle (which is owned by the main application, not by us)
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGui_ImplOSX_ViewportData* vd = IM_NEW(ImGui_ImplOSX_ViewportData)();
+    vd->Window = bd->Window;
+    vd->WindowOwned = false;
+    main_viewport->PlatformUserData = vd;
+    main_viewport->PlatformHandle = (__bridge void*)bd->Window;
+
+    [NSNotificationCenter.defaultCenter addObserver:bd->Observer
+                                           selector:@selector(displaysDidChange:)
+                                               name:NSApplicationDidChangeScreenParametersNotification
+                                             object:nil];
+}
+
+static void ImGui_ImplOSX_ShutdownMultiViewportSupport()
+{
+    ImGui_ImplOSX_Data* bd = ImGui_ImplOSX_GetBackendData();
+    [NSNotificationCenter.defaultCenter removeObserver:bd->Observer
+                                                  name:NSApplicationDidChangeScreenParametersNotification
+                                                object:nil];
+    bd->Observer = nullptr;
+    bd->Window = nullptr;
+    if (bd->Monitor != nullptr)
+    {
+        [NSEvent removeMonitor:bd->Monitor];
+        bd->Monitor = nullptr;
+    }
+
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGui_ImplOSX_ViewportData* vd = (ImGui_ImplOSX_ViewportData*)main_viewport->PlatformUserData;
+    IM_DELETE(vd);
+    main_viewport->PlatformUserData = nullptr;
+    ImGui::DestroyPlatformWindows();
+}
+
 //-----------------------------------------------------------------------------
 
 #endif // #ifndef IMGUI_DISABLE

diff --git a/backends/imgui_impl_sdl2.cpp b/backends/imgui_impl_sdl2.cpp
index f578977..a8387d8 100644
--- a/backends/imgui_impl_sdl2.cpp
+++ b/backends/imgui_impl_sdl2.cpp

@@ -10,6 +10,10 @@
 //  [X] Platform: Gamepad support.
 //  [X] Platform: Mouse cursor shape and visibility (ImGuiBackendFlags_HasMouseCursors). Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
 //  [X] Platform: Basic IME support. App needs to call 'SDL_SetHint(SDL_HINT_IME_SHOW_UI, "1");' before SDL_CreateWindow()!.
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
+// Missing features or Issues:
+//  [ ] Platform: Multi-viewport: Minimized windows seems to break mouse wheel events (at least under Windows).
+//  [ ] Platform: Multi-viewport: Missing ImGuiBackendFlags_HasParentViewport support. The viewport->ParentViewportID field is ignored, and therefore io.ConfigViewportsNoDefaultParent has no effect either.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -21,6 +25,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2026-02-13: Inputs: systems other than X11 are back to starting mouse capture on mouse down (reverts 2025-02-26 change). Only X11 requires waiting for a drag by default (not ideal, but a better default for X11 users). Added ImGui_ImplSDL2_SetMouseCaptureMode() for X11 debugger users. (#3650, #6410, #9235)
 //  2026-01-15: Changed GetClipboardText() handler to return nullptr on error aka clipboard contents is not text. Consistent with other backends. (#9168)
 //  2025-09-24: Skip using the SDL_GetGlobalMouseState() state when one of our window is hovered, as the SDL_MOUSEMOTION data is reliable. Fix macOS notch mouse coordinates issue in fullscreen mode + better perf on X11. (#7919, #7786)
@@ -28,11 +33,15 @@
 //  2025-09-15: Content Scales are always reported as 1.0 on Wayland. (#8921)
 //  2025-07-08: Made ImGui_ImplSDL2_GetContentScaleForWindow(), ImGui_ImplSDL2_GetContentScaleForDisplay() helpers return 1.0f on Emscripten and Android platforms, matching macOS logic. (#8742, #8733)
 //  2025-06-11: Added ImGui_ImplSDL2_GetContentScaleForWindow(SDL_Window* window) and ImGui_ImplSDL2_GetContentScaleForDisplay(int display_index) helper to facilitate making DPI-aware apps.
+//  2025-05-15: [Docking] Add Platform_GetWindowFramebufferScale() handler, to allow varying Retina display density on multiple monitors.
+//  2025-04-09: [Docking] Revert update monitors and work areas information every frame. Only do it on Windows. (#8415, #8558)
 //  2025-04-09: Don't attempt to call SDL_CaptureMouse() on drivers where we don't call SDL_GetGlobalMouseState(). (#8561)
 //  2025-03-21: Fill gamepad inputs and set ImGuiBackendFlags_HasGamepad regardless of ImGuiConfigFlags_NavEnableGamepad being set.
 //  2025-03-10: When dealing with OEM keys, use scancodes instead of translated keycodes to choose ImGuiKey values. (#7136, #7201, #7206, #7306, #7670, #7672, #8468)
 //  2025-02-26: Only start SDL_CaptureMouse() when mouse is being dragged, to mitigate issues with e.g. Linux debuggers not claiming capture back. (#6410, #3650)
+//  2025-02-25: [Docking] Revert to use SDL_GetDisplayBounds() for WorkPos/WorkRect if SDL_GetDisplayUsableBounds() failed.
 //  2025-02-24: Avoid calling SDL_GetGlobalMouseState() when mouse is in relative mode.
+//  2025-02-21: [Docking] Update monitors and work areas information every frame, as the later may change regardless of monitor changes. (#8415)
 //  2025-02-18: Added ImGuiMouseCursor_Wait and ImGuiMouseCursor_Progress mouse cursor support.
 //  2025-02-10: Using SDL_OpenURL() in platform_io.Platform_OpenInShellFn handler.
 //  2025-01-20: Made ImGui_ImplSDL2_SetGamepadMode(ImGui_ImplSDL2_GamepadMode_Manual) accept an empty array.
@@ -73,7 +82,7 @@
 //  2022-01-10: Inputs: calling new io.AddKeyEvent(), io.AddKeyModsEvent() + io.SetKeyEventNativeData() API (1.87+). Support for full ImGuiKey range.
 //  2021-08-17: Calling io.AddFocusEvent() on SDL_WINDOWEVENT_FOCUS_GAINED/SDL_WINDOWEVENT_FOCUS_LOST.
 //  2021-07-29: Inputs: MousePos is correctly reported when the host platform window is hovered but not focused (using SDL_GetMouseFocus() + SDL_HINT_MOUSE_FOCUS_CLICKTHROUGH, requires SDL 2.0.5+)
-//  2021-06-29: *BREAKING CHANGE* Removed 'SDL_Window* window' parameter to ImGui_ImplSDL2_NewFrame() which was unnecessary.
+//  2021-06:29: *BREAKING CHANGE* Removed 'SDL_Window* window' parameter to ImGui_ImplSDL2_NewFrame() which was unnecessary.
 //  2021-06-29: Reorganized backend to pull data from a single structure to facilitate usage with multiple-contexts (all g_XXXX access changed to bd->XXXX).
 //  2021-03-22: Rework global mouse pos availability check listing supported platforms explicitly, effectively fixing mouse access on Raspberry Pi. (#2837, #3950)
 //  2020-05-25: Misc: Report a zero display-size when window is minimized, to be consistent with other backends.
@@ -115,6 +124,7 @@
 #endif
 
 // SDL
+// (the multi-viewports feature requires SDL features supported from SDL 2.0.4+. SDL 2.0.5+ is highly recommended)
 #include <SDL.h>
 #include <SDL_syswm.h>
 #include <stdio.h>              // for snprintf()
@@ -131,11 +141,18 @@
 #else
 #define SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE    0
 #endif
+#define SDL_HAS_WINDOW_ALPHA                SDL_VERSION_ATLEAST(2,0,5)
+#define SDL_HAS_ALWAYS_ON_TOP               SDL_VERSION_ATLEAST(2,0,5)
+#define SDL_HAS_USABLE_DISPLAY_BOUNDS       SDL_VERSION_ATLEAST(2,0,5)
 #define SDL_HAS_PER_MONITOR_DPI             SDL_VERSION_ATLEAST(2,0,4)
 #define SDL_HAS_VULKAN                      SDL_VERSION_ATLEAST(2,0,6)
+#define SDL_HAS_DISPLAY_EVENT               SDL_VERSION_ATLEAST(2,0,9)
 #define SDL_HAS_OPEN_URL                    SDL_VERSION_ATLEAST(2,0,14)
+#define SDL_HAS_SHOW_WINDOW_ACTIVATION_HINT SDL_VERSION_ATLEAST(2,0,18)
 #if SDL_HAS_VULKAN
 #include <SDL_vulkan.h>
+#else
+static const Uint32 SDL_WINDOW_VULKAN = 0x10000000;
 #endif
 
 // SDL Data
@@ -147,6 +164,8 @@
     Uint64                  Time;
     char*                   ClipboardTextData;
     char                    BackendPlatformName[48];
+    bool                    UseVulkan;
+    bool                    WantUpdateMonitors;
 
     // Mouse handling
     Uint32                  MouseWindowID;
@@ -155,6 +174,7 @@
     SDL_Cursor*             MouseLastCursor;
     int                     MouseLastLeaveFrame;
     bool                    MouseCanUseGlobalState;
+    bool                    MouseCanReportHoveredViewport;  // This is hard to use/unreliable on SDL so we'll set ImGuiBackendFlags_HasMouseHoveredViewport dynamically based on state.
     ImGui_ImplSDL2_MouseCaptureMode MouseCaptureMode;
 
     // Gamepad handling
@@ -174,6 +194,11 @@
     return ImGui::GetCurrentContext() ? (ImGui_ImplSDL2_Data*)ImGui::GetIO().BackendPlatformUserData : nullptr;
 }
 
+// Forward Declarations
+static void ImGui_ImplSDL2_UpdateMonitors();
+static void ImGui_ImplSDL2_InitMultiViewportSupport(SDL_Window* window, void* sdl_gl_context);
+static void ImGui_ImplSDL2_ShutdownMultiViewportSupport();
+
 // Functions
 static const char* ImGui_ImplSDL2_GetClipboardText(ImGuiContext*)
 {
@@ -193,13 +218,13 @@
 }
 
 // Note: native IME will only display if user calls SDL_SetHint(SDL_HINT_IME_SHOW_UI, "1") _before_ SDL_CreateWindow().
-static void ImGui_ImplSDL2_PlatformSetImeData(ImGuiContext*, ImGuiViewport*, ImGuiPlatformImeData* data)
+static void ImGui_ImplSDL2_PlatformSetImeData(ImGuiContext*, ImGuiViewport* viewport, ImGuiPlatformImeData* data)
 {
     if (data->WantVisible)
     {
         SDL_Rect r;
-        r.x = (int)data->InputPos.x;
-        r.y = (int)data->InputPos.y;
+        r.x = (int)(data->InputPos.x - viewport->Pos.x);
+        r.y = (int)(data->InputPos.y - viewport->Pos.y);
         r.w = 1;
         r.h = (int)data->InputLineHeight;
         SDL_SetTextInputRect(&r);
@@ -365,8 +390,7 @@
 
 static ImGuiViewport* ImGui_ImplSDL2_GetViewportForWindowID(Uint32 window_id)
 {
-    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
-    return (window_id == bd->WindowID) ? ImGui::GetMainViewport() : nullptr;
+    return ImGui::FindViewportByPlatformHandle((void*)(intptr_t)window_id);
 }
 
 // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
@@ -386,6 +410,13 @@
             if (ImGui_ImplSDL2_GetViewportForWindowID(event->motion.windowID) == nullptr)
                 return false;
             ImVec2 mouse_pos((float)event->motion.x, (float)event->motion.y);
+            if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+            {
+                int window_x, window_y;
+                SDL_GetWindowPosition(SDL_GetWindowFromID(event->motion.windowID), &window_x, &window_y);
+                mouse_pos.x += window_x;
+                mouse_pos.y += window_y;
+            }
             io.AddMouseSourceEvent(event->motion.which == SDL_TOUCH_MOUSEID ? ImGuiMouseSource_TouchScreen : ImGuiMouseSource_Mouse);
             io.AddMousePosEvent(mouse_pos.x, mouse_pos.y);
             return true;
@@ -437,20 +468,32 @@
         case SDL_KEYDOWN:
         case SDL_KEYUP:
         {
-            if (ImGui_ImplSDL2_GetViewportForWindowID(event->key.windowID) == nullptr)
+            ImGuiViewport* viewport = ImGui_ImplSDL2_GetViewportForWindowID(event->key.windowID);
+            if (viewport == nullptr)
                 return false;
+            //IMGUI_DEBUG_LOG("SDL_KEY%s : key=0x%08X ('%s'), scancode=%d ('%s'), mod=%X, windowID=%d, viewport=%08X\n",
+            //    (event->type == SDL_KEYDOWN) ? "DOWN" : "UP  ", event->key.keysym.sym, SDL_GetKeyName(event->key.keysym.sym), event->key.keysym.scancode, SDL_GetScancodeName(event->key.keysym.scancode), event->key.keysym.mod, event->key.windowID, viewport ? viewport->ID : 0);
             ImGui_ImplSDL2_UpdateKeyModifiers((SDL_Keymod)event->key.keysym.mod);
-            //IMGUI_DEBUG_LOG("SDL_KEY_%s : key=%d ('%s'), scancode=%d ('%s'), mod=%X\n",
-            //    (event->type == SDL_KEYDOWN) ? "DOWN" : "UP  ", event->key.keysym.sym, SDL_GetKeyName(event->key.keysym.sym), event->key.keysym.scancode, SDL_GetScancodeName(event->key.keysym.scancode), event->key.keysym.mod);
             ImGuiKey key = ImGui_ImplSDL2_KeyEventToImGuiKey(event->key.keysym.sym, event->key.keysym.scancode);
             io.AddKeyEvent(key, (event->type == SDL_KEYDOWN));
             io.SetKeyEventNativeData(key, (int)event->key.keysym.sym, (int)event->key.keysym.scancode, (int)event->key.keysym.scancode); // To support legacy indexing (<1.87 user code). Legacy backend uses SDLK_*** as indices to IsKeyXXX() functions.
             return true;
         }
+#if SDL_HAS_DISPLAY_EVENT
+        case SDL_DISPLAYEVENT:
+        {
+            // 2.0.26 has SDL_DISPLAYEVENT_CONNECTED/SDL_DISPLAYEVENT_DISCONNECTED/SDL_DISPLAYEVENT_ORIENTATION,
+            // so change of DPI/Scaling are not reflected in this event. (SDL3 has it)
+            bd->WantUpdateMonitors = true;
+            return true;
+        }
+#endif
         case SDL_WINDOWEVENT:
         {
-            if (ImGui_ImplSDL2_GetViewportForWindowID(event->window.windowID) == nullptr)
+            ImGuiViewport* viewport = ImGui_ImplSDL2_GetViewportForWindowID(event->window.windowID);
+            if (viewport == NULL)
                 return false;
+
             // - When capturing mouse, SDL will send a bunch of conflicting LEAVE/ENTER event on every mouse move, but the final ENTER tends to be right.
             // - However we won't get a correct LEAVE event for a captured window.
             // - In some cases, when detaching a window from main viewport SDL may send SDL_WINDOWEVENT_ENTER one frame too late,
@@ -464,10 +507,18 @@
             }
             if (window_event == SDL_WINDOWEVENT_LEAVE)
                 bd->MouseLastLeaveFrame = ImGui::GetFrameCount() + 1;
+            //if (window_event == SDL_WINDOWEVENT_FOCUS_GAINED) { IMGUI_DEBUG_LOG("SDL_WINDOWEVENT_FOCUS_GAINED: windowId %d, viewport: %08X\n", event->window.windowID, viewport ? viewport->ID : 0); }
+            //if (window_event == SDL_WINDOWEVENT_FOCUS_LOST) { IMGUI_DEBUG_LOG("SDL_WINDOWEVENT_FOCUS_LOST: windowId %d, viewport: %08X\n", event->window.windowID, viewport ? viewport->ID : 0); }
             if (window_event == SDL_WINDOWEVENT_FOCUS_GAINED)
                 io.AddFocusEvent(true);
             if (window_event == SDL_WINDOWEVENT_FOCUS_LOST)
                 io.AddFocusEvent(false);
+            if (window_event == SDL_WINDOWEVENT_CLOSE)
+                viewport->PlatformRequestClose = true;
+            if (window_event == SDL_WINDOWEVENT_MOVED)
+                viewport->PlatformRequestMove = true;
+            if (window_event == SDL_WINDOWEVENT_RESIZED)
+                viewport->PlatformRequestResize = true;
             return true;
         }
         case SDL_CONTROLLERDEVICEADDED:
@@ -507,11 +558,20 @@
     io.BackendPlatformName = bd->BackendPlatformName;
     io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;           // We can honor GetMouseCursor() values (optional)
     io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;            // We can honor io.WantSetMousePos requests (optional, rarely used)
+    // (ImGuiBackendFlags_PlatformHasViewports may be set just below)
 
     bd->Window = window;
     bd->WindowID = SDL_GetWindowID(window);
     bd->Renderer = renderer;
 
+    // SDL on Linux/OSX doesn't report events for unfocused windows (see https://github.com/ocornut/imgui/issues/4960)
+    // We will use 'MouseCanReportHoveredViewport' to set 'ImGuiBackendFlags_HasMouseHoveredViewport' dynamically each frame.
+#ifndef __APPLE__
+    bd->MouseCanReportHoveredViewport = bd->MouseCanUseGlobalState;
+#else
+    bd->MouseCanReportHoveredViewport = false;
+#endif
+
     // Check and store if we are on a SDL backend that supports SDL_GetGlobalMouseState() and SDL_CaptureMouse()
     // ("wayland" and "rpi" don't support it, but we chose to use a white-list instead of a black-list)
     bd->MouseCanUseGlobalState = false;
@@ -526,6 +586,8 @@
             bd->MouseCaptureMode = (strcmp(item, "x11") == 0) ? ImGui_ImplSDL2_MouseCaptureMode_EnabledAfterDrag : ImGui_ImplSDL2_MouseCaptureMode_Enabled;
         }
 #endif
+    if (bd->MouseCanUseGlobalState)
+        io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports;  // We can create multi-viewports on the Platform side (optional)
 
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
     platform_io.Platform_SetClipboardTextFn = ImGui_ImplSDL2_SetClipboardText;
@@ -538,6 +600,9 @@
     platform_io.Platform_OpenInShellFn = [](ImGuiContext*, const char* url) { return SDL_OpenURL(url) == 0; };
 #endif
 
+    // Update monitor a first time during init
+    ImGui_ImplSDL2_UpdateMonitors();
+
     // Gamepad handling
     bd->GamepadMode = ImGui_ImplSDL2_GamepadMode_AutoFirst;
     bd->WantUpdateGamepadsList = true;
@@ -592,7 +657,11 @@
     SDL_SetHint(SDL_HINT_MOUSE_AUTO_CAPTURE, "0");
 #endif
 
-    (void)sdl_gl_context; // Unused in 'master' branch.
+    // We need SDL_CaptureMouse(), SDL_GetGlobalMouseState() from SDL 2.0.4+ to support multiple viewports.
+    // We left the call to ImGui_ImplSDL2_InitMultiViewportSupport() outside of #ifdef to avoid unused-function warnings.
+    if (io.BackendFlags & ImGuiBackendFlags_PlatformHasViewports)
+        ImGui_ImplSDL2_InitMultiViewportSupport(window, sdl_gl_context);
+
     return true;
 }
 
@@ -606,7 +675,11 @@
 #if !SDL_HAS_VULKAN
     IM_ASSERT(0 && "Unsupported");
 #endif
-    return ImGui_ImplSDL2_Init(window, nullptr, nullptr);
+    if (!ImGui_ImplSDL2_Init(window, nullptr, nullptr))
+        return false;
+    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
+    bd->UseVulkan = true;
+    return true;
 }
 
 bool ImGui_ImplSDL2_InitForD3D(SDL_Window* window)
@@ -641,6 +714,7 @@
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
+    ImGui_ImplSDL2_ShutdownMultiViewportSupport();
     if (bd->ClipboardTextData)
         SDL_free(bd->ClipboardTextData);
     for (ImGuiMouseCursor cursor_n = 0; cursor_n < ImGuiMouseCursor_COUNT; cursor_n++)
@@ -649,7 +723,7 @@
 
     io.BackendPlatformName = nullptr;
     io.BackendPlatformUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad);
+    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad | ImGuiBackendFlags_PlatformHasViewports | ImGuiBackendFlags_HasMouseHoveredViewport);
     platform_io.ClearPlatformHandlers();
     IM_DELETE(bd);
 }
@@ -662,6 +736,7 @@
     bd->MouseCaptureMode = mode;
 }
 
+// This code is rather messy because some of the functions we need for full viewport support are not available in SDL < 2.0.4.
 static void ImGui_ImplSDL2_UpdateMouseData()
 {
     ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
@@ -685,16 +760,24 @@
     }
 
     SDL_Window* focused_window = SDL_GetKeyboardFocus();
-    const bool is_app_focused = (bd->Window == focused_window);
+    const bool is_app_focused = (focused_window && (bd->Window == focused_window || ImGui_ImplSDL2_GetViewportForWindowID(SDL_GetWindowID(focused_window)) != NULL));
 #else
     SDL_Window* focused_window = bd->Window;
     const bool is_app_focused = (SDL_GetWindowFlags(bd->Window) & SDL_WINDOW_INPUT_FOCUS) != 0; // SDL 2.0.3 and non-windowed systems: single-viewport only
 #endif
+
     if (is_app_focused)
     {
         // (Optional) Set OS mouse position from Dear ImGui if requested (rarely used, only when io.ConfigNavMoveSetMousePos is enabled by user)
         if (io.WantSetMousePos)
-            SDL_WarpMouseInWindow(bd->Window, (int)io.MousePos.x, (int)io.MousePos.y);
+        {
+#if SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE
+            if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+                SDL_WarpMouseGlobal((int)io.MousePos.x, (int)io.MousePos.y);
+            else
+#endif
+                SDL_WarpMouseInWindow(bd->Window, (int)io.MousePos.x, (int)io.MousePos.y);
+        }
 
         // (Optional) Fallback to provide unclamped mouse position when focused but not hovered (SDL_MOUSEMOTION already provides this when hovered or captured)
         // Note that SDL_GetGlobalMouseState() is in theory slow on X11, but this only runs on rather specific cases. If a problem we may provide a way to opt-out this feature.
@@ -703,15 +786,34 @@
         if (hovered_window == nullptr && bd->MouseCanUseGlobalState && bd->MouseButtonsDown == 0 && !is_relative_mouse_mode)
         {
             // Single-viewport mode: mouse position in client window coordinates (io.MousePos is (0,0) when the mouse is on the upper-left corner of the app window)
+            // Multi-viewport mode: mouse position in OS absolute coordinates (io.MousePos is (0,0) when the mouse is on the upper-left of the primary monitor)
             int mouse_x, mouse_y;
             int window_x, window_y;
             SDL_GetGlobalMouseState(&mouse_x, &mouse_y);
-            SDL_GetWindowPosition(focused_window, &window_x, &window_y);
-            mouse_x -= window_x;
-            mouse_y -= window_y;
+            if (!(io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable))
+            {
+                SDL_GetWindowPosition(focused_window, &window_x, &window_y);
+                mouse_x -= window_x;
+                mouse_y -= window_y;
+            }
             io.AddMousePosEvent((float)mouse_x, (float)mouse_y);
         }
     }
+
+    // (Optional) When using multiple viewports: call io.AddMouseViewportEvent() with the viewport the OS mouse cursor is hovering.
+    // If ImGuiBackendFlags_HasMouseHoveredViewport is not set by the backend, Dear imGui will ignore this field and infer the information using its flawed heuristic.
+    // - [!] SDL backend does NOT correctly ignore viewports with the _NoInputs flag.
+    //       Some backend are not able to handle that correctly. If a backend report an hovered viewport that has the _NoInputs flag (e.g. when dragging a window
+    //       for docking, the viewport has the _NoInputs flag in order to allow us to find the viewport under), then Dear ImGui is forced to ignore the value reported
+    //       by the backend, and use its flawed heuristic to guess the viewport behind.
+    // - [X] SDL backend correctly reports this regardless of another viewport behind focused and dragged from (we need this to find a useful drag and drop target).
+    if (io.BackendFlags & ImGuiBackendFlags_HasMouseHoveredViewport)
+    {
+        ImGuiID mouse_viewport_id = 0;
+        if (ImGuiViewport* mouse_viewport = ImGui_ImplSDL2_GetViewportForWindowID(bd->MouseWindowID))
+            mouse_viewport_id = mouse_viewport->ID;
+        io.AddMouseViewportEvent(mouse_viewport_id);
+    }
 }
 
 static void ImGui_ImplSDL2_UpdateMouseCursor()
@@ -866,6 +968,38 @@
     ImGui_ImplSDL2_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadRStickDown,  SDL_CONTROLLER_AXIS_RIGHTY, +thumb_dead_zone, +32767);
 }
 
+// FIXME: Note that doesn't update with DPI/Scaling change only as SDL2 doesn't have an event for it (SDL3 has).
+static void ImGui_ImplSDL2_UpdateMonitors()
+{
+    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Monitors.resize(0);
+    bd->WantUpdateMonitors = false;
+    int display_count = SDL_GetNumVideoDisplays();
+    for (int n = 0; n < display_count; n++)
+    {
+        // Warning: the validity of monitor DPI information on Windows depends on the application DPI awareness settings, which generally needs to be set in the manifest or at runtime.
+        ImGuiPlatformMonitor monitor;
+        SDL_Rect r;
+        SDL_GetDisplayBounds(n, &r);
+        monitor.MainPos = monitor.WorkPos = ImVec2((float)r.x, (float)r.y);
+        monitor.MainSize = monitor.WorkSize = ImVec2((float)r.w, (float)r.h);
+#if SDL_HAS_USABLE_DISPLAY_BOUNDS
+        if (SDL_GetDisplayUsableBounds(n, &r) == 0 && r.w > 0 && r.h > 0)
+        {
+            monitor.WorkPos = ImVec2((float)r.x, (float)r.y);
+            monitor.WorkSize = ImVec2((float)r.w, (float)r.h);
+        }
+#endif
+        float dpi_scale = ImGui_ImplSDL2_GetContentScaleForDisplay(n);
+        if (dpi_scale <= 0.0f)
+            continue; // Some accessibility applications are declaring virtual monitors with a DPI of 0, see #7902.
+        monitor.DpiScale = dpi_scale;
+        monitor.PlatformHandle = (void*)(intptr_t)n;
+        platform_io.Monitors.push_back(monitor);
+    }
+}
+
 static void ImGui_ImplSDL2_GetWindowSizeAndFramebufferScale(SDL_Window* window, SDL_Renderer* renderer, ImVec2* out_size, ImVec2* out_framebuffer_scale)
 {
     int w, h;
@@ -896,6 +1030,13 @@
     // Setup main viewport size (every frame to accommodate for window resizing)
     ImGui_ImplSDL2_GetWindowSizeAndFramebufferScale(bd->Window, bd->Renderer, &io.DisplaySize, &io.DisplayFramebufferScale);
 
+    // Update monitors
+#ifdef WIN32
+    bd->WantUpdateMonitors = true; // Keep polling under Windows to handle changes of work area when resizing task-bar (#8415)
+#endif
+    if (bd->WantUpdateMonitors)
+        ImGui_ImplSDL2_UpdateMonitors();
+
     // Setup time step (we don't use SDL_GetTicks() because it is using millisecond resolution)
     // (Accept SDL_GetPerformanceCounter() not returning a monotonically increasing value. Happens in VMs and Emscripten, see #6189, #6114, #3644)
     static Uint64 frequency = SDL_GetPerformanceFrequency();
@@ -912,6 +1053,13 @@
         io.AddMousePosEvent(-FLT_MAX, -FLT_MAX);
     }
 
+    // Our io.AddMouseViewportEvent() calls will only be valid when not capturing.
+    // Technically speaking testing for 'bd->MouseButtonsDown == 0' would be more rigorous, but testing for payload reduces noise and potential side-effects.
+    if (bd->MouseCanReportHoveredViewport && ImGui::GetDragDropPayload() == nullptr)
+        io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport;
+    else
+        io.BackendFlags &= ~ImGuiBackendFlags_HasMouseHoveredViewport;
+
     ImGui_ImplSDL2_UpdateMouseData();
     ImGui_ImplSDL2_UpdateMouseCursor();
 
@@ -919,6 +1067,266 @@
     ImGui_ImplSDL2_UpdateGamepads();
 }
 
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* PlatformUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGui_ImplSDL2_ViewportData
+{
+    SDL_Window*     Window;
+    Uint32          WindowID;       // Stored in ImGuiViewport::PlatformHandle. Use SDL_GetWindowFromID() to get SDL_Window* from Uint32 WindowID.
+    bool            WindowOwned;
+    SDL_GLContext   GLContext;
+
+    ImGui_ImplSDL2_ViewportData()   { Window = nullptr; WindowID = 0; WindowOwned = false; GLContext = nullptr; }
+    ~ImGui_ImplSDL2_ViewportData()  { IM_ASSERT(Window == nullptr && GLContext == nullptr); }
+};
+
+static void ImGui_ImplSDL2_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
+    ImGui_ImplSDL2_ViewportData* vd = IM_NEW(ImGui_ImplSDL2_ViewportData)();
+    viewport->PlatformUserData = vd;
+
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGui_ImplSDL2_ViewportData* main_viewport_data = (ImGui_ImplSDL2_ViewportData*)main_viewport->PlatformUserData;
+
+    // Share GL resources with main context
+    bool use_opengl = (main_viewport_data->GLContext != nullptr);
+    SDL_GLContext backup_context = nullptr;
+    if (use_opengl)
+    {
+        backup_context = SDL_GL_GetCurrentContext();
+        SDL_GL_SetAttribute(SDL_GL_SHARE_WITH_CURRENT_CONTEXT, 1);
+        SDL_GL_MakeCurrent(main_viewport_data->Window, main_viewport_data->GLContext);
+    }
+
+    Uint32 sdl_flags = 0;
+    sdl_flags |= use_opengl ? SDL_WINDOW_OPENGL : (bd->UseVulkan ? SDL_WINDOW_VULKAN : 0);
+    sdl_flags |= SDL_GetWindowFlags(bd->Window) & SDL_WINDOW_ALLOW_HIGHDPI;
+    sdl_flags |= SDL_WINDOW_HIDDEN;
+    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? SDL_WINDOW_BORDERLESS : 0;
+    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? 0 : SDL_WINDOW_RESIZABLE;
+#if !defined(_WIN32)
+    // See SDL hack in ImGui_ImplSDL2_ShowWindow().
+    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoTaskBarIcon) ? SDL_WINDOW_SKIP_TASKBAR : 0;
+#endif
+#if SDL_HAS_ALWAYS_ON_TOP
+    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_TopMost) ? SDL_WINDOW_ALWAYS_ON_TOP : 0;
+#endif
+    vd->Window = SDL_CreateWindow("No Title Yet", (int)viewport->Pos.x, (int)viewport->Pos.y, (int)viewport->Size.x, (int)viewport->Size.y, sdl_flags);
+    vd->WindowOwned = true;
+    if (use_opengl)
+    {
+        vd->GLContext = SDL_GL_CreateContext(vd->Window);
+        SDL_GL_SetSwapInterval(0);
+    }
+    if (use_opengl && backup_context)
+        SDL_GL_MakeCurrent(vd->Window, backup_context);
+
+    viewport->PlatformHandle = (void*)(intptr_t)SDL_GetWindowID(vd->Window);
+    viewport->PlatformHandleRaw = nullptr;
+    SDL_SysWMinfo info;
+    SDL_VERSION(&info.version);
+    if (SDL_GetWindowWMInfo(vd->Window, &info))
+    {
+#if defined(SDL_VIDEO_DRIVER_WINDOWS)
+        viewport->PlatformHandleRaw = info.info.win.window;
+#elif defined(__APPLE__) && defined(SDL_VIDEO_DRIVER_COCOA)
+        viewport->PlatformHandleRaw = (void*)info.info.cocoa.window;
+#endif
+    }
+}
+
+static void ImGui_ImplSDL2_DestroyWindow(ImGuiViewport* viewport)
+{
+    if (ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData)
+    {
+        if (vd->GLContext && vd->WindowOwned)
+            SDL_GL_DeleteContext(vd->GLContext);
+        if (vd->Window && vd->WindowOwned)
+            SDL_DestroyWindow(vd->Window);
+        vd->GLContext = nullptr;
+        vd->Window = nullptr;
+        IM_DELETE(vd);
+    }
+    viewport->PlatformUserData = viewport->PlatformHandle = nullptr;
+}
+
+static void ImGui_ImplSDL2_ShowWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+#if defined(_WIN32) && !(defined(WINAPI_FAMILY) && ((defined(WINAPI_FAMILY_APP) && WINAPI_FAMILY == WINAPI_FAMILY_APP) || (defined(WINAPI_FAMILY_GAMES) && WINAPI_FAMILY == WINAPI_FAMILY_GAMES)))
+    HWND hwnd = (HWND)viewport->PlatformHandleRaw;
+
+    // SDL hack: Hide icon from task bar
+    // Note: SDL 2.0.6+ has a SDL_WINDOW_SKIP_TASKBAR flag which is supported under Windows but the way it create the window breaks our seamless transition.
+    if (viewport->Flags & ImGuiViewportFlags_NoTaskBarIcon)
+    {
+        LONG ex_style = ::GetWindowLong(hwnd, GWL_EXSTYLE);
+        ex_style &= ~WS_EX_APPWINDOW;
+        ex_style |= WS_EX_TOOLWINDOW;
+        ::SetWindowLong(hwnd, GWL_EXSTYLE, ex_style);
+    }
+#endif
+
+#if SDL_HAS_SHOW_WINDOW_ACTIVATION_HINT
+    SDL_SetHint(SDL_HINT_WINDOW_NO_ACTIVATION_WHEN_SHOWN, (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing) ? "1" : "0");
+#elif defined(_WIN32)
+    // SDL hack: SDL always activate/focus windows :/
+    if (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing)
+    {
+        ::ShowWindow(hwnd, SW_SHOWNA);
+        return;
+    }
+#endif
+    SDL_ShowWindow(vd->Window);
+}
+
+static ImVec2 ImGui_ImplSDL2_GetWindowPos(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+    int x = 0, y = 0;
+    SDL_GetWindowPosition(vd->Window, &x, &y);
+    return ImVec2((float)x, (float)y);
+}
+
+static void ImGui_ImplSDL2_SetWindowPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+    SDL_SetWindowPosition(vd->Window, (int)pos.x, (int)pos.y);
+}
+
+static ImVec2 ImGui_ImplSDL2_GetWindowSize(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+    int w = 0, h = 0;
+    SDL_GetWindowSize(vd->Window, &w, &h);
+    return ImVec2((float)w, (float)h);
+}
+
+static void ImGui_ImplSDL2_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+    SDL_SetWindowSize(vd->Window, (int)size.x, (int)size.y);
+}
+
+static ImVec2 ImGui_ImplSDL2_GetWindowFramebufferScale(ImGuiViewport* viewport)
+{
+    // FIXME: SDL_Renderer does not support multi-viewport.
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+    ImVec2 framebuffer_scale;
+    ImGui_ImplSDL2_GetWindowSizeAndFramebufferScale(vd->Window, nullptr, nullptr, &framebuffer_scale);
+    return framebuffer_scale;
+}
+
+static void ImGui_ImplSDL2_SetWindowTitle(ImGuiViewport* viewport, const char* title)
+{
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+    SDL_SetWindowTitle(vd->Window, title);
+}
+
+#if SDL_HAS_WINDOW_ALPHA
+static void ImGui_ImplSDL2_SetWindowAlpha(ImGuiViewport* viewport, float alpha)
+{
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+    SDL_SetWindowOpacity(vd->Window, alpha);
+}
+#endif
+
+static void ImGui_ImplSDL2_SetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+    SDL_RaiseWindow(vd->Window);
+}
+
+static bool ImGui_ImplSDL2_GetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+    return (SDL_GetWindowFlags(vd->Window) & SDL_WINDOW_INPUT_FOCUS) != 0;
+}
+
+static bool ImGui_ImplSDL2_GetWindowMinimized(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+    return (SDL_GetWindowFlags(vd->Window) & SDL_WINDOW_MINIMIZED) != 0;
+}
+
+static void ImGui_ImplSDL2_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+    if (vd->GLContext)
+        SDL_GL_MakeCurrent(vd->Window, vd->GLContext);
+}
+
+static void ImGui_ImplSDL2_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+    if (vd->GLContext)
+    {
+        SDL_GL_MakeCurrent(vd->Window, vd->GLContext);
+        SDL_GL_SwapWindow(vd->Window);
+    }
+}
+
+// Vulkan support (the Vulkan renderer needs to call a platform-side support function to create the surface)
+// SDL is graceful enough to _not_ need <vulkan/vulkan.h> so we can safely include this.
+#if SDL_HAS_VULKAN
+#include <SDL_vulkan.h>
+static int ImGui_ImplSDL2_CreateVkSurface(ImGuiViewport* viewport, ImU64 vk_instance, const void* vk_allocator, ImU64* out_vk_surface)
+{
+    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
+    (void)vk_allocator;
+    SDL_bool ret = SDL_Vulkan_CreateSurface(vd->Window, (VkInstance)vk_instance, (VkSurfaceKHR*)out_vk_surface);
+    return ret ? 0 : 1; // ret ? VK_SUCCESS : VK_NOT_READY
+}
+#endif // SDL_HAS_VULKAN
+
+static void ImGui_ImplSDL2_InitMultiViewportSupport(SDL_Window* window, void* sdl_gl_context)
+{
+    // Register platform interface (will be coupled with a renderer interface)
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Platform_CreateWindow = ImGui_ImplSDL2_CreateWindow;
+    platform_io.Platform_DestroyWindow = ImGui_ImplSDL2_DestroyWindow;
+    platform_io.Platform_ShowWindow = ImGui_ImplSDL2_ShowWindow;
+    platform_io.Platform_SetWindowPos = ImGui_ImplSDL2_SetWindowPos;
+    platform_io.Platform_GetWindowPos = ImGui_ImplSDL2_GetWindowPos;
+    platform_io.Platform_SetWindowSize = ImGui_ImplSDL2_SetWindowSize;
+    platform_io.Platform_GetWindowSize = ImGui_ImplSDL2_GetWindowSize;
+    platform_io.Platform_GetWindowFramebufferScale = ImGui_ImplSDL2_GetWindowFramebufferScale;
+    platform_io.Platform_SetWindowFocus = ImGui_ImplSDL2_SetWindowFocus;
+    platform_io.Platform_GetWindowFocus = ImGui_ImplSDL2_GetWindowFocus;
+    platform_io.Platform_GetWindowMinimized = ImGui_ImplSDL2_GetWindowMinimized;
+    platform_io.Platform_SetWindowTitle = ImGui_ImplSDL2_SetWindowTitle;
+    platform_io.Platform_RenderWindow = ImGui_ImplSDL2_RenderWindow;
+    platform_io.Platform_SwapBuffers = ImGui_ImplSDL2_SwapBuffers;
+#if SDL_HAS_WINDOW_ALPHA
+    platform_io.Platform_SetWindowAlpha = ImGui_ImplSDL2_SetWindowAlpha;
+#endif
+#if SDL_HAS_VULKAN
+    platform_io.Platform_CreateVkSurface = ImGui_ImplSDL2_CreateVkSurface;
+#endif
+
+    // Register main window handle (which is owned by the main application, not by us)
+    // This is mostly for simplicity and consistency, so that our code (e.g. mouse handling etc.) can use same logic for main and secondary viewports.
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGui_ImplSDL2_ViewportData* vd = IM_NEW(ImGui_ImplSDL2_ViewportData)();
+    vd->Window = window;
+    vd->WindowID = SDL_GetWindowID(window);
+    vd->WindowOwned = false;
+    vd->GLContext = sdl_gl_context;
+    main_viewport->PlatformUserData = vd;
+    main_viewport->PlatformHandle = (void*)(intptr_t)vd->WindowID;
+}
+
+static void ImGui_ImplSDL2_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
 //-----------------------------------------------------------------------------
 
 #if defined(__clang__)

diff --git a/backends/imgui_impl_sdl2.h b/backends/imgui_impl_sdl2.h
index 63ef707..e091ba3 100644
--- a/backends/imgui_impl_sdl2.h
+++ b/backends/imgui_impl_sdl2.h

@@ -9,6 +9,10 @@
 //  [X] Platform: Gamepad support.
 //  [X] Platform: Mouse cursor shape and visibility (ImGuiBackendFlags_HasMouseCursors). Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
 //  [X] Platform: Basic IME support. App needs to call 'SDL_SetHint(SDL_HINT_IME_SHOW_UI, "1");' before SDL_CreateWindow()!.
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
+// Missing features or Issues:
+//  [ ] Platform: Multi-viewport: Minimized windows seems to break mouse wheel events (at least under Windows).
+//  [ ] Platform: Multi-viewport: Missing ImGuiBackendFlags_HasParentViewport support. The viewport->ParentViewportID field is ignored, and therefore io.ConfigViewportsNoDefaultParent has no effect either.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_sdl3.cpp b/backends/imgui_impl_sdl3.cpp
index a2bd606..5ca8166 100644
--- a/backends/imgui_impl_sdl3.cpp
+++ b/backends/imgui_impl_sdl3.cpp

@@ -8,7 +8,10 @@
 //  [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy SDL_SCANCODE_* values are obsolete since 1.87 and not supported since 1.91.5]
 //  [X] Platform: Gamepad support.
 //  [X] Platform: Mouse cursor shape and visibility (ImGuiBackendFlags_HasMouseCursors). Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
-//  [X] Platform: IME support.
+//  [x] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable' -> the OS animation effect when window gets created/destroyed is problematic. SDL2 backend doesn't have issue.
+// Missing features or Issues:
+//  [ ] Platform: Multi-viewport: Minimized windows seems to break mouse wheel events (at least under Windows).
+//  [x] Platform: IME support. Position somehow broken in SDL3 + app needs to call 'SDL_SetHint(SDL_HINT_IME_SHOW_UI, "1");' before SDL_CreateWindow()!.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -20,6 +23,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2026-02-13: Inputs: systems other than X11 are back to starting mouse capture on mouse down (reverts 2025-02-26 change). Only X11 requires waiting for a drag by default (not ideal, but a better default for X11 users). Added ImGui_ImplSDL3_SetMouseCaptureMode() for X11 debugger users. (#3650, #6410, #9235)
 //  2026-01-15: Changed GetClipboardText() handler to return nullptr on error aka clipboard contents is not text. Consistent with other backends. (#9168)
 //  2025-11-05: Fixed an issue with missing characters events when an already active text field changes viewports. (#9054)
@@ -28,17 +32,23 @@
 //  2025-09-18: Call platform_io.ClearPlatformHandlers() on shutdown.
 //  2025-09-15: Use SDL_GetWindowDisplayScale() on Mac to output DisplayFrameBufferScale. The function is more reliable during resolution changes e.g. going fullscreen. (#8703, #4414)
 //  2025-06-27: IME: avoid calling SDL_StartTextInput() again if already active. (#8727)
+//  2025-05-15: [Docking] Add Platform_GetWindowFramebufferScale() handler, to allow varying Retina display density on multiple monitors.
+//  2025-05-06: [Docking] macOS: fixed secondary viewports not appearing on other monitors before of parenting.
+//  2025-04-09: [Docking] Revert update monitors and work areas information every frame. Only do it on Windows. (#8415, #8558)
 //  2025-04-22: IME: honor ImGuiPlatformImeData->WantTextInput as an alternative way to call SDL_StartTextInput(), without IME being necessarily visible.
 //  2025-04-09: Don't attempt to call SDL_CaptureMouse() on drivers where we don't call SDL_GetGlobalMouseState(). (#8561)
 //  2025-03-30: Update for SDL3 api changes: Revert SDL_GetClipboardText() memory ownership change. (#8530, #7801)
 //  2025-03-21: Fill gamepad inputs and set ImGuiBackendFlags_HasGamepad regardless of ImGuiConfigFlags_NavEnableGamepad being set.
 //  2025-03-10: When dealing with OEM keys, use scancodes instead of translated keycodes to choose ImGuiKey values. (#7136, #7201, #7206, #7306, #7670, #7672, #8468)
 //  2025-02-26: Only start SDL_CaptureMouse() when mouse is being dragged, to mitigate issues with e.g. Linux debuggers not claiming capture back. (#6410, #3650)
+//  2025-02-25: [Docking] Revert to use SDL_GetDisplayBounds() for WorkPos/WorkRect if SDL_GetDisplayUsableBounds() failed.
 //  2025-02-24: Avoid calling SDL_GetGlobalMouseState() when mouse is in relative mode.
+//  2025-02-21: [Docking] Update monitors and work areas information every frame, as the later may change regardless of monitor changes. (#8415)
 //  2025-02-18: Added ImGuiMouseCursor_Wait and ImGuiMouseCursor_Progress mouse cursor support.
 //  2025-02-10: Using SDL_OpenURL() in platform_io.Platform_OpenInShellFn handler.
 //  2025-01-20: Made ImGui_ImplSDL3_SetGamepadMode(ImGui_ImplSDL3_GamepadMode_Manual) accept an empty array.
 //  2024-10-24: Emscripten: SDL_EVENT_MOUSE_WHEEL event doesn't require dividing by 100.0f on Emscripten.
+//  2024-09-11: (Docking) Added support for viewport->ParentViewportId field to support parenting at OS level. (#7973)
 //  2024-09-03: Update for SDL3 api changes: SDL_GetGamepads() memory ownership revert. (#7918, #7898, #7807)
 //  2024-08-22: moved some OS/backend related function pointers from ImGuiIO to ImGuiPlatformIO:
 //               - io.GetClipboardTextFn    -> platform_io.Platform_GetClipboardTextFn
@@ -112,6 +122,8 @@
     Uint64                  Time;
     char*                   ClipboardTextData;
     char                    BackendPlatformName[48];
+    bool                    UseVulkan;
+    bool                    WantUpdateMonitors;
 
     // IME handling
     SDL_Window*             ImeWindow;
@@ -125,12 +137,13 @@
     SDL_Cursor*             MouseLastCursor;
     int                     MousePendingLeaveFrame;
     bool                    MouseCanUseGlobalState;
+    bool                    MouseCanReportHoveredViewport;  // This is hard to use/unreliable on SDL so we'll set ImGuiBackendFlags_HasMouseHoveredViewport dynamically based on state.
     ImGui_ImplSDL3_MouseCaptureMode MouseCaptureMode;
 
     // Gamepad handling
-    ImVector<SDL_Gamepad*>      Gamepads;
+    ImVector<SDL_Gamepad*>  Gamepads;
     ImGui_ImplSDL3_GamepadMode  GamepadMode;
-    bool                        WantUpdateGamepadsList;
+    bool                    WantUpdateGamepadsList;
 
     ImGui_ImplSDL3_Data()   { memset((void*)this, 0, sizeof(*this)); }
 };
@@ -146,6 +159,9 @@
 
 // Forward Declarations
 static void ImGui_ImplSDL3_UpdateIme();
+static void ImGui_ImplSDL3_UpdateMonitors();
+static void ImGui_ImplSDL3_InitMultiViewportSupport(SDL_Window* window, void* sdl_gl_context);
+static void ImGui_ImplSDL3_ShutdownMultiViewportSupport();
 
 // Functions
 static const char* ImGui_ImplSDL3_GetClipboardText(ImGuiContext*)
@@ -167,8 +183,7 @@
 
 static ImGuiViewport* ImGui_ImplSDL3_GetViewportForWindowID(SDL_WindowID window_id)
 {
-    ImGui_ImplSDL3_Data* bd = ImGui_ImplSDL3_GetBackendData();
-    return (window_id == bd->WindowID) ? ImGui::GetMainViewport() : nullptr;
+    return ImGui::FindViewportByPlatformHandle((void*)(intptr_t)window_id);
 }
 
 static void ImGui_ImplSDL3_PlatformSetImeData(ImGuiContext*, ImGuiViewport*, ImGuiPlatformImeData* data)
@@ -199,9 +214,12 @@
     bd->ImeDirty = false;
     if (data->WantVisible)
     {
+        ImVec2 viewport_pos;
+        if (ImGuiViewport* viewport = ImGui_ImplSDL3_GetViewportForWindowID(SDL_GetWindowID(window)))
+            viewport_pos = viewport->Pos;
         SDL_Rect r;
-        r.x = (int)data->InputPos.x;
-        r.y = (int)data->InputPos.y;
+        r.x = (int)(data->InputPos.x - viewport_pos.x);
+        r.y = (int)(data->InputPos.y - viewport_pos.y);
         r.w = 1;
         r.h = (int)data->InputLineHeight;
         SDL_SetTextInputArea(window, &r, 0);
@@ -390,6 +408,13 @@
             if (ImGui_ImplSDL3_GetViewportForWindowID(event->motion.windowID) == nullptr)
                 return false;
             ImVec2 mouse_pos((float)event->motion.x, (float)event->motion.y);
+            if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+            {
+                int window_x, window_y;
+                SDL_GetWindowPosition(SDL_GetWindowFromID(event->motion.windowID), &window_x, &window_y);
+                mouse_pos.x += window_x;
+                mouse_pos.y += window_y;
+            }
             io.AddMouseSourceEvent(event->motion.which == SDL_TOUCH_MOUSEID ? ImGuiMouseSource_TouchScreen : ImGuiMouseSource_Mouse);
             io.AddMousePosEvent(mouse_pos.x, mouse_pos.y);
             return true;
@@ -433,16 +458,26 @@
         case SDL_EVENT_KEY_DOWN:
         case SDL_EVENT_KEY_UP:
         {
-            if (ImGui_ImplSDL3_GetViewportForWindowID(event->key.windowID) == nullptr)
+            ImGuiViewport* viewport = ImGui_ImplSDL3_GetViewportForWindowID(event->key.windowID);
+            if (viewport == nullptr)
                 return false;
+            //IMGUI_DEBUG_LOG("SDL_EVENT_KEY_%s : key=0x%08X ('%s'), scancode=%d ('%s'), mod=%X, windowID=%d, viewport=%08X\n",
+            //    (event->type == SDL_EVENT_KEY_DOWN) ? "DOWN" : "UP  ", event->key.key, SDL_GetKeyName(event->key.key), event->key.scancode, SDL_GetScancodeName(event->key.scancode), event->key.mod, event->key.windowID, viewport ? viewport->ID : 0);
             ImGui_ImplSDL3_UpdateKeyModifiers((SDL_Keymod)event->key.mod);
-            //IMGUI_DEBUG_LOG("SDL_EVENT_KEY_%s : key=%d ('%s'), scancode=%d ('%s'), mod=%X\n",
-            //    (event->type == SDL_EVENT_KEY_DOWN) ? "DOWN" : "UP  ", event->key.key, SDL_GetKeyName(event->key.key), event->key.scancode, SDL_GetScancodeName(event->key.scancode), event->key.mod);
             ImGuiKey key = ImGui_ImplSDL3_KeyEventToImGuiKey(event->key.key, event->key.scancode);
             io.AddKeyEvent(key, (event->type == SDL_EVENT_KEY_DOWN));
             io.SetKeyEventNativeData(key, (int)event->key.key, (int)event->key.scancode, (int)event->key.scancode); // To support legacy indexing (<1.87 user code). Legacy backend uses SDLK_*** as indices to IsKeyXXX() functions.
             return true;
         }
+        case SDL_EVENT_DISPLAY_ORIENTATION:
+        case SDL_EVENT_DISPLAY_ADDED:
+        case SDL_EVENT_DISPLAY_REMOVED:
+        case SDL_EVENT_DISPLAY_MOVED:
+        case SDL_EVENT_DISPLAY_CONTENT_SCALE_CHANGED:
+        {
+            bd->WantUpdateMonitors = true;
+            return true;
+        }
         case SDL_EVENT_WINDOW_MOUSE_ENTER:
         {
             if (ImGui_ImplSDL3_GetViewportForWindowID(event->window.windowID) == nullptr)
@@ -465,11 +500,28 @@
         case SDL_EVENT_WINDOW_FOCUS_GAINED:
         case SDL_EVENT_WINDOW_FOCUS_LOST:
         {
-            if (ImGui_ImplSDL3_GetViewportForWindowID(event->window.windowID) == nullptr)
+            ImGuiViewport* viewport = ImGui_ImplSDL3_GetViewportForWindowID(event->window.windowID);
+            if (viewport == nullptr)
                 return false;
+            //IMGUI_DEBUG_LOG("%s: windowId %d, viewport: %08X\n", (event->type == SDL_EVENT_WINDOW_FOCUS_GAINED) ? "SDL_EVENT_WINDOW_FOCUS_GAINED" : "SDL_WINDOWEVENT_FOCUS_LOST", event->window.windowID, viewport ? viewport->ID : 0);
             io.AddFocusEvent(event->type == SDL_EVENT_WINDOW_FOCUS_GAINED);
             return true;
         }
+        case SDL_EVENT_WINDOW_CLOSE_REQUESTED:
+        case SDL_EVENT_WINDOW_MOVED:
+        case SDL_EVENT_WINDOW_RESIZED:
+        {
+            ImGuiViewport* viewport = ImGui_ImplSDL3_GetViewportForWindowID(event->window.windowID);
+            if (viewport == NULL)
+                return false;
+            if (event->type == SDL_EVENT_WINDOW_CLOSE_REQUESTED)
+                viewport->PlatformRequestClose = true;
+            if (event->type == SDL_EVENT_WINDOW_MOVED)
+                viewport->PlatformRequestMove = true;
+            if (event->type == SDL_EVENT_WINDOW_RESIZED)
+                viewport->PlatformRequestResize = true;
+            return true;
+        }
         case SDL_EVENT_GAMEPAD_ADDED:
         case SDL_EVENT_GAMEPAD_REMOVED:
         {
@@ -511,11 +563,21 @@
     io.BackendPlatformName = bd->BackendPlatformName;
     io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;           // We can honor GetMouseCursor() values (optional)
     io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;            // We can honor io.WantSetMousePos requests (optional, rarely used)
+    // (ImGuiBackendFlags_PlatformHasViewports and ImGuiBackendFlags_HasParentViewport may be set just below)
+    // (ImGuiBackendFlags_HasMouseHoveredViewport is set dynamically in our _NewFrame function)
 
     bd->Window = window;
     bd->WindowID = SDL_GetWindowID(window);
     bd->Renderer = renderer;
 
+    // SDL on Linux/OSX doesn't report events for unfocused windows (see https://github.com/ocornut/imgui/issues/4960)
+    // We will use 'MouseCanReportHoveredViewport' to set 'ImGuiBackendFlags_HasMouseHoveredViewport' dynamically each frame.
+#ifndef __APPLE__
+    bd->MouseCanReportHoveredViewport = bd->MouseCanUseGlobalState;
+#else
+    bd->MouseCanReportHoveredViewport = false;
+#endif
+
     // Check and store if we are on a SDL backend that supports SDL_GetGlobalMouseState() and SDL_CaptureMouse()
     // ("wayland" and "rpi" don't support it, but we chose to use a white-list instead of a black-list)
     bd->MouseCanUseGlobalState = false;
@@ -530,6 +592,11 @@
             bd->MouseCaptureMode = (strcmp(item, "x11") == 0) ? ImGui_ImplSDL3_MouseCaptureMode_EnabledAfterDrag : ImGui_ImplSDL3_MouseCaptureMode_Enabled;
         }
 #endif
+    if (bd->MouseCanUseGlobalState)
+    {
+        io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports;  // We can create multi-viewports on the Platform side (optional)
+        io.BackendFlags |= ImGuiBackendFlags_HasParentViewport;     // We can honor viewport->ParentViewportId by applying the corresponding parent/child relationship at platform level (optional)
+    }
 
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
     platform_io.Platform_SetClipboardTextFn = ImGui_ImplSDL3_SetClipboardText;
@@ -537,6 +604,9 @@
     platform_io.Platform_SetImeDataFn = ImGui_ImplSDL3_PlatformSetImeData;
     platform_io.Platform_OpenInShellFn = [](ImGuiContext*, const char* url) { return SDL_OpenURL(url); };
 
+    // Update monitor a first time during init
+    ImGui_ImplSDL3_UpdateMonitors();
+
     // Gamepad handling
     bd->GamepadMode = ImGui_ImplSDL3_GamepadMode_AutoFirst;
     bd->WantUpdateGamepadsList = true;
@@ -569,6 +639,14 @@
     // From 2.0.22: Disable auto-capture, this is preventing drag and drop across multiple windows (see #5710)
     SDL_SetHint(SDL_HINT_MOUSE_AUTO_CAPTURE, "0");
 
+    // SDL 3.x : see https://github.com/libsdl-org/SDL/issues/6659
+    SDL_SetHint("SDL_BORDERLESS_WINDOWED_STYLE", "0");
+
+    // We need SDL_CaptureMouse(), SDL_GetGlobalMouseState() from SDL 2.0.4+ to support multiple viewports.
+    // We left the call to ImGui_ImplSDL3_InitPlatformInterface() outside of #ifdef to avoid unused-function warnings.
+    if (io.BackendFlags & ImGuiBackendFlags_PlatformHasViewports)
+        ImGui_ImplSDL3_InitMultiViewportSupport(window, sdl_gl_context);
+
     return true;
 }
 
@@ -580,7 +658,11 @@
 
 bool ImGui_ImplSDL3_InitForVulkan(SDL_Window* window)
 {
-    return ImGui_ImplSDL3_Init(window, nullptr, nullptr);
+    if (!ImGui_ImplSDL3_Init(window, nullptr, nullptr))
+        return false;
+    ImGui_ImplSDL3_Data* bd = ImGui_ImplSDL3_GetBackendData();
+    bd->UseVulkan = true;
+    return true;
 }
 
 bool ImGui_ImplSDL3_InitForD3D(SDL_Window* window)
@@ -620,6 +702,7 @@
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
+    ImGui_ImplSDL3_ShutdownMultiViewportSupport();
     if (bd->ClipboardTextData)
         SDL_free(bd->ClipboardTextData);
     for (ImGuiMouseCursor cursor_n = 0; cursor_n < ImGuiMouseCursor_COUNT; cursor_n++)
@@ -628,7 +711,7 @@
 
     io.BackendPlatformName = nullptr;
     io.BackendPlatformUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad);
+    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad | ImGuiBackendFlags_PlatformHasViewports | ImGuiBackendFlags_HasMouseHoveredViewport | ImGuiBackendFlags_HasParentViewport);
     platform_io.ClearPlatformHandlers();
     IM_DELETE(bd);
 }
@@ -664,7 +747,7 @@
     }
 
     SDL_Window* focused_window = SDL_GetKeyboardFocus();
-    const bool is_app_focused = (bd->Window == focused_window);
+    const bool is_app_focused = (focused_window && (bd->Window == focused_window || ImGui_ImplSDL3_GetViewportForWindowID(SDL_GetWindowID(focused_window)) != NULL));
 #else
     SDL_Window* focused_window = bd->Window;
     const bool is_app_focused = (SDL_GetWindowFlags(bd->Window) & SDL_WINDOW_INPUT_FOCUS) != 0; // SDL 2.0.3 and non-windowed systems: single-viewport only
@@ -673,7 +756,14 @@
     {
         // (Optional) Set OS mouse position from Dear ImGui if requested (rarely used, only when io.ConfigNavMoveSetMousePos is enabled by user)
         if (io.WantSetMousePos)
-            SDL_WarpMouseInWindow(bd->Window, io.MousePos.x, io.MousePos.y);
+        {
+#if SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE
+            if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+                SDL_WarpMouseGlobal(io.MousePos.x, io.MousePos.y);
+            else
+#endif
+                SDL_WarpMouseInWindow(bd->Window, io.MousePos.x, io.MousePos.y);
+        }
 
         // (Optional) Fallback to provide unclamped mouse position when focused but not hovered (SDL_EVENT_MOUSE_MOTION already provides this when hovered or captured)
         // Note that SDL_GetGlobalMouseState() is in theory slow on X11, but this only runs on rather specific cases. If a problem we may provide a way to opt-out this feature.
@@ -682,15 +772,34 @@
         if (hovered_window == nullptr && bd->MouseCanUseGlobalState && bd->MouseButtonsDown == 0 && !is_relative_mouse_mode)
         {
             // Single-viewport mode: mouse position in client window coordinates (io.MousePos is (0,0) when the mouse is on the upper-left corner of the app window)
+            // Multi-viewport mode: mouse position in OS absolute coordinates (io.MousePos is (0,0) when the mouse is on the upper-left of the primary monitor)
             float mouse_x, mouse_y;
             int window_x, window_y;
             SDL_GetGlobalMouseState(&mouse_x, &mouse_y);
-            SDL_GetWindowPosition(focused_window, &window_x, &window_y);
-            mouse_x -= window_x;
-            mouse_y -= window_y;
+            if (!(io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable))
+            {
+                SDL_GetWindowPosition(focused_window, &window_x, &window_y);
+                mouse_x -= window_x;
+                mouse_y -= window_y;
+            }
             io.AddMousePosEvent(mouse_x, mouse_y);
         }
     }
+
+    // (Optional) When using multiple viewports: call io.AddMouseViewportEvent() with the viewport the OS mouse cursor is hovering.
+    // If ImGuiBackendFlags_HasMouseHoveredViewport is not set by the backend, Dear imGui will ignore this field and infer the information using its flawed heuristic.
+    // - [!] SDL backend does NOT correctly ignore viewports with the _NoInputs flag.
+    //       Some backend are not able to handle that correctly. If a backend report an hovered viewport that has the _NoInputs flag (e.g. when dragging a window
+    //       for docking, the viewport has the _NoInputs flag in order to allow us to find the viewport under), then Dear ImGui is forced to ignore the value reported
+    //       by the backend, and use its flawed heuristic to guess the viewport behind.
+    // - [X] SDL backend correctly reports this regardless of another viewport behind focused and dragged from (we need this to find a useful drag and drop target).
+    if (io.BackendFlags & ImGuiBackendFlags_HasMouseHoveredViewport)
+    {
+        ImGuiID mouse_viewport_id = 0;
+        if (ImGuiViewport* mouse_viewport = ImGui_ImplSDL3_GetViewportForWindowID(bd->MouseWindowID))
+            mouse_viewport_id = mouse_viewport->ID;
+        io.AddMouseViewportEvent(mouse_viewport_id);
+    }
 }
 
 static void ImGui_ImplSDL3_UpdateMouseCursor()
@@ -822,6 +931,38 @@
     ImGui_ImplSDL3_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadRStickDown,  SDL_GAMEPAD_AXIS_RIGHTY, +thumb_dead_zone, +32767);
 }
 
+static void ImGui_ImplSDL3_UpdateMonitors()
+{
+    ImGui_ImplSDL3_Data* bd = ImGui_ImplSDL3_GetBackendData();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Monitors.resize(0);
+    bd->WantUpdateMonitors = false;
+
+    int display_count;
+    SDL_DisplayID* displays = SDL_GetDisplays(&display_count);
+    for (int n = 0; n < display_count; n++)
+    {
+        // Warning: the validity of monitor DPI information on Windows depends on the application DPI awareness settings, which generally needs to be set in the manifest or at runtime.
+        SDL_DisplayID display_id = displays[n];
+        ImGuiPlatformMonitor monitor;
+        SDL_Rect r;
+        SDL_GetDisplayBounds(display_id, &r);
+        monitor.MainPos = monitor.WorkPos = ImVec2((float)r.x, (float)r.y);
+        monitor.MainSize = monitor.WorkSize = ImVec2((float)r.w, (float)r.h);
+        if (SDL_GetDisplayUsableBounds(display_id, &r) && r.w > 0 && r.h > 0)
+        {
+            monitor.WorkPos = ImVec2((float)r.x, (float)r.y);
+            monitor.WorkSize = ImVec2((float)r.w, (float)r.h);
+        }
+        monitor.DpiScale = SDL_GetDisplayContentScale(display_id); // See https://wiki.libsdl.org/SDL3/README-highdpi for details.
+        monitor.PlatformHandle = (void*)(intptr_t)n;
+        if (monitor.DpiScale <= 0.0f)
+            continue; // Some accessibility applications are declaring virtual monitors with a DPI of 0, see #7902.
+        platform_io.Monitors.push_back(monitor);
+    }
+    SDL_free(displays);
+}
+
 static void ImGui_ImplSDL3_GetWindowSizeAndFramebufferScale(SDL_Window* window, ImVec2* out_size, ImVec2* out_framebuffer_scale)
 {
     int w, h;
@@ -854,6 +995,13 @@
     // Setup main viewport size (every frame to accommodate for window resizing)
     ImGui_ImplSDL3_GetWindowSizeAndFramebufferScale(bd->Window, &io.DisplaySize, &io.DisplayFramebufferScale);
 
+    // Update monitors
+#ifdef WIN32
+    bd->WantUpdateMonitors = true; // Keep polling under Windows to handle changes of work area when resizing task-bar (#8415)
+#endif
+    if (bd->WantUpdateMonitors)
+        ImGui_ImplSDL3_UpdateMonitors();
+
     // Setup time step (we could also use SDL_GetTicksNS() available since SDL3)
     // (Accept SDL_GetPerformanceCounter() not returning a monotonically increasing value. Happens in VMs and Emscripten, see #6189, #6114, #3644)
     static Uint64 frequency = SDL_GetPerformanceFrequency();
@@ -870,6 +1018,13 @@
         io.AddMousePosEvent(-FLT_MAX, -FLT_MAX);
     }
 
+    // Our io.AddMouseViewportEvent() calls will only be valid when not capturing.
+    // Technically speaking testing for 'bd->MouseButtonsDown == 0' would be more rigorous, but testing for payload reduces noise and potential side-effects.
+    if (bd->MouseCanReportHoveredViewport && ImGui::GetDragDropPayload() == nullptr)
+        io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport;
+    else
+        io.BackendFlags &= ~ImGuiBackendFlags_HasMouseHoveredViewport;
+
     ImGui_ImplSDL3_UpdateMouseData();
     ImGui_ImplSDL3_UpdateMouseCursor();
     ImGui_ImplSDL3_UpdateIme();
@@ -878,6 +1033,272 @@
     ImGui_ImplSDL3_UpdateGamepads();
 }
 
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* PlatformUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGui_ImplSDL3_ViewportData
+{
+    SDL_Window*     Window;
+    SDL_Window*     ParentWindow;
+    Uint32          WindowID;       // Stored in ImGuiViewport::PlatformHandle. Use SDL_GetWindowFromID() to get SDL_Window* from Uint32 WindowID.
+    bool            WindowOwned;
+    SDL_GLContext   GLContext;
+
+    ImGui_ImplSDL3_ViewportData()   { Window = ParentWindow = nullptr; WindowID = 0; WindowOwned = false; GLContext = nullptr; }
+    ~ImGui_ImplSDL3_ViewportData()  { IM_ASSERT(Window == nullptr && GLContext == nullptr); }
+};
+
+static SDL_Window* ImGui_ImplSDL3_GetSDLWindowFromViewport(ImGuiViewport* viewport)
+{
+    if (viewport != nullptr)
+    {
+        SDL_WindowID window_id = (SDL_WindowID)(intptr_t)viewport->PlatformHandle;
+        return SDL_GetWindowFromID(window_id);
+    }
+    return nullptr;
+}
+
+static void ImGui_ImplSDL3_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL3_Data* bd = ImGui_ImplSDL3_GetBackendData();
+    ImGui_ImplSDL3_ViewportData* vd = IM_NEW(ImGui_ImplSDL3_ViewportData)();
+    viewport->PlatformUserData = vd;
+
+    vd->ParentWindow = ImGui_ImplSDL3_GetSDLWindowFromViewport(viewport->ParentViewport);
+
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGui_ImplSDL3_ViewportData* main_viewport_data = (ImGui_ImplSDL3_ViewportData*)main_viewport->PlatformUserData;
+
+    // Share GL resources with main context
+    bool use_opengl = (main_viewport_data->GLContext != nullptr);
+    SDL_GLContext backup_context = nullptr;
+    if (use_opengl)
+    {
+        backup_context = SDL_GL_GetCurrentContext();
+        SDL_GL_SetAttribute(SDL_GL_SHARE_WITH_CURRENT_CONTEXT, 1);
+        SDL_GL_MakeCurrent(main_viewport_data->Window, main_viewport_data->GLContext);
+    }
+
+    SDL_WindowFlags sdl_flags = 0;
+    sdl_flags |= SDL_WINDOW_HIDDEN;
+    sdl_flags |= use_opengl ? SDL_WINDOW_OPENGL : (bd->UseVulkan ? SDL_WINDOW_VULKAN : 0);
+    sdl_flags |= SDL_GetWindowFlags(bd->Window) & SDL_WINDOW_HIGH_PIXEL_DENSITY;
+    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? SDL_WINDOW_BORDERLESS : 0;
+    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? 0 : SDL_WINDOW_RESIZABLE;
+    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoTaskBarIcon) ? SDL_WINDOW_UTILITY : 0;
+    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_TopMost) ? SDL_WINDOW_ALWAYS_ON_TOP : 0;
+    vd->Window = SDL_CreateWindow("No Title Yet", (int)viewport->Size.x, (int)viewport->Size.y, sdl_flags);
+#ifndef __APPLE__ // On Mac, SDL3 Parenting appears to prevent viewport from appearing in another monitor
+    SDL_SetWindowParent(vd->Window, vd->ParentWindow);
+#endif
+    SDL_SetWindowPosition(vd->Window, (int)viewport->Pos.x, (int)viewport->Pos.y);
+    vd->WindowOwned = true;
+    if (use_opengl)
+    {
+        vd->GLContext = SDL_GL_CreateContext(vd->Window);
+        SDL_GL_SetSwapInterval(0);
+    }
+    if (use_opengl && backup_context)
+        SDL_GL_MakeCurrent(vd->Window, backup_context);
+
+    ImGui_ImplSDL3_SetupPlatformHandles(viewport, vd->Window);
+}
+
+static void ImGui_ImplSDL3_DestroyWindow(ImGuiViewport* viewport)
+{
+    if (ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData)
+    {
+        if (vd->GLContext && vd->WindowOwned)
+            SDL_GL_DestroyContext(vd->GLContext);
+        if (vd->Window && vd->WindowOwned)
+            SDL_DestroyWindow(vd->Window);
+        vd->GLContext = nullptr;
+        vd->Window = nullptr;
+        IM_DELETE(vd);
+    }
+    viewport->PlatformUserData = viewport->PlatformHandle = nullptr;
+}
+
+static void ImGui_ImplSDL3_ShowWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+#if defined(_WIN32) && !(defined(WINAPI_FAMILY) && ((defined(WINAPI_FAMILY_APP) && WINAPI_FAMILY == WINAPI_FAMILY_APP) || (defined(WINAPI_FAMILY_GAMES) && WINAPI_FAMILY == WINAPI_FAMILY_GAMES)))
+    HWND hwnd = (HWND)viewport->PlatformHandleRaw;
+
+    // SDL hack: Show icon in task bar (#7989)
+    // Note: SDL_WINDOW_UTILITY can be used to control task bar visibility, but on Windows, it does not affect child windows.
+    if (!(viewport->Flags & ImGuiViewportFlags_NoTaskBarIcon))
+    {
+        LONG ex_style = ::GetWindowLong(hwnd, GWL_EXSTYLE);
+        ex_style |= WS_EX_APPWINDOW;
+        ex_style &= ~WS_EX_TOOLWINDOW;
+        ::ShowWindow(hwnd, SW_HIDE);
+        ::SetWindowLong(hwnd, GWL_EXSTYLE, ex_style);
+    }
+#endif
+
+#ifdef __APPLE__
+    SDL_SetHint(SDL_HINT_WINDOW_ACTIVATE_WHEN_SHOWN, "1"); // Otherwise new window appear under
+#else
+    SDL_SetHint(SDL_HINT_WINDOW_ACTIVATE_WHEN_SHOWN, (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing) ? "0" : "1");
+#endif
+    SDL_ShowWindow(vd->Window);
+}
+
+static void ImGui_ImplSDL3_UpdateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    IM_UNUSED(vd);
+
+#ifndef __APPLE__ // On Mac, SDL3 Parenting appears to prevent viewport from appearing in another monitor
+    // Update SDL3 parent if it changed _after_ creation.
+    // This is for advanced apps that are manipulating ParentViewportID manually.
+    SDL_Window* new_parent = ImGui_ImplSDL3_GetSDLWindowFromViewport(viewport->ParentViewport);
+    if (new_parent != vd->ParentWindow)
+    {
+        vd->ParentWindow = new_parent;
+        SDL_SetWindowParent(vd->Window, vd->ParentWindow);
+    }
+#endif
+}
+
+static ImVec2 ImGui_ImplSDL3_GetWindowPos(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    int x = 0, y = 0;
+    SDL_GetWindowPosition(vd->Window, &x, &y);
+    return ImVec2((float)x, (float)y);
+}
+
+static void ImGui_ImplSDL3_SetWindowPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    SDL_SetWindowPosition(vd->Window, (int)pos.x, (int)pos.y);
+}
+
+static ImVec2 ImGui_ImplSDL3_GetWindowSize(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    int w = 0, h = 0;
+    SDL_GetWindowSize(vd->Window, &w, &h);
+    return ImVec2((float)w, (float)h);
+}
+
+static void ImGui_ImplSDL3_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    SDL_SetWindowSize(vd->Window, (int)size.x, (int)size.y);
+}
+
+static ImVec2 ImGui_ImplSDL3_GetWindowFramebufferScale(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    ImVec2 framebuffer_scale;
+    ImGui_ImplSDL3_GetWindowSizeAndFramebufferScale(vd->Window, nullptr, &framebuffer_scale);
+    return framebuffer_scale;
+}
+
+static void ImGui_ImplSDL3_SetWindowTitle(ImGuiViewport* viewport, const char* title)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    SDL_SetWindowTitle(vd->Window, title);
+}
+
+static void ImGui_ImplSDL3_SetWindowAlpha(ImGuiViewport* viewport, float alpha)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    SDL_SetWindowOpacity(vd->Window, alpha);
+}
+
+static void ImGui_ImplSDL3_SetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    SDL_RaiseWindow(vd->Window);
+}
+
+static bool ImGui_ImplSDL3_GetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    return (SDL_GetWindowFlags(vd->Window) & SDL_WINDOW_INPUT_FOCUS) != 0;
+}
+
+static bool ImGui_ImplSDL3_GetWindowMinimized(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    return (SDL_GetWindowFlags(vd->Window) & SDL_WINDOW_MINIMIZED) != 0;
+}
+
+static void ImGui_ImplSDL3_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    if (vd->GLContext)
+        SDL_GL_MakeCurrent(vd->Window, vd->GLContext);
+}
+
+static void ImGui_ImplSDL3_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    if (vd->GLContext)
+    {
+        SDL_GL_MakeCurrent(vd->Window, vd->GLContext);
+        SDL_GL_SwapWindow(vd->Window);
+    }
+}
+
+// Vulkan support (the Vulkan renderer needs to call a platform-side support function to create the surface)
+// SDL is graceful enough to _not_ need <vulkan/vulkan.h> so we can safely include this.
+#include <SDL3/SDL_vulkan.h>
+static int ImGui_ImplSDL3_CreateVkSurface(ImGuiViewport* viewport, ImU64 vk_instance, const void* vk_allocator, ImU64* out_vk_surface)
+{
+    ImGui_ImplSDL3_ViewportData* vd = (ImGui_ImplSDL3_ViewportData*)viewport->PlatformUserData;
+    (void)vk_allocator;
+    bool ret = SDL_Vulkan_CreateSurface(vd->Window, (VkInstance)vk_instance, (const VkAllocationCallbacks*)vk_allocator, (VkSurfaceKHR*)out_vk_surface);
+    return ret ? 0 : 1; // ret ? VK_SUCCESS : VK_NOT_READY
+}
+
+static void ImGui_ImplSDL3_InitMultiViewportSupport(SDL_Window* window, void* sdl_gl_context)
+{
+    // Register platform interface (will be coupled with a renderer interface)
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Platform_CreateWindow = ImGui_ImplSDL3_CreateWindow;
+    platform_io.Platform_DestroyWindow = ImGui_ImplSDL3_DestroyWindow;
+    platform_io.Platform_ShowWindow = ImGui_ImplSDL3_ShowWindow;
+    platform_io.Platform_UpdateWindow = ImGui_ImplSDL3_UpdateWindow;
+    platform_io.Platform_SetWindowPos = ImGui_ImplSDL3_SetWindowPos;
+    platform_io.Platform_GetWindowPos = ImGui_ImplSDL3_GetWindowPos;
+    platform_io.Platform_SetWindowSize = ImGui_ImplSDL3_SetWindowSize;
+    platform_io.Platform_GetWindowSize = ImGui_ImplSDL3_GetWindowSize;
+    platform_io.Platform_GetWindowFramebufferScale = ImGui_ImplSDL3_GetWindowFramebufferScale;
+    platform_io.Platform_SetWindowFocus = ImGui_ImplSDL3_SetWindowFocus;
+    platform_io.Platform_GetWindowFocus = ImGui_ImplSDL3_GetWindowFocus;
+    platform_io.Platform_GetWindowMinimized = ImGui_ImplSDL3_GetWindowMinimized;
+    platform_io.Platform_SetWindowTitle = ImGui_ImplSDL3_SetWindowTitle;
+    platform_io.Platform_RenderWindow = ImGui_ImplSDL3_RenderWindow;
+    platform_io.Platform_SwapBuffers = ImGui_ImplSDL3_SwapBuffers;
+    platform_io.Platform_SetWindowAlpha = ImGui_ImplSDL3_SetWindowAlpha;
+    platform_io.Platform_CreateVkSurface = ImGui_ImplSDL3_CreateVkSurface;
+
+    // Register main window handle (which is owned by the main application, not by us)
+    // This is mostly for simplicity and consistency, so that our code (e.g. mouse handling etc.) can use same logic for main and secondary viewports.
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGui_ImplSDL3_ViewportData* vd = IM_NEW(ImGui_ImplSDL3_ViewportData)();
+    vd->Window = window;
+    vd->WindowID = SDL_GetWindowID(window);
+    vd->WindowOwned = false;
+    vd->GLContext = (SDL_GLContext)sdl_gl_context;
+    main_viewport->PlatformUserData = vd;
+    main_viewport->PlatformHandle = (void*)(intptr_t)vd->WindowID;
+}
+
+static void ImGui_ImplSDL3_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
 //-----------------------------------------------------------------------------
 
 #if defined(__clang__)

diff --git a/backends/imgui_impl_sdl3.h b/backends/imgui_impl_sdl3.h
index 0720283..7e57913 100644
--- a/backends/imgui_impl_sdl3.h
+++ b/backends/imgui_impl_sdl3.h

@@ -8,7 +8,10 @@
 //  [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy SDL_SCANCODE_* values are obsolete since 1.87 and not supported since 1.91.5]
 //  [X] Platform: Gamepad support.
 //  [X] Platform: Mouse cursor shape and visibility (ImGuiBackendFlags_HasMouseCursors). Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
-//  [X] Platform: IME support.
+//  [x] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable' -> the OS animation effect when window gets created/destroyed is problematic. SDL2 backend doesn't have issue.
+// Missing features or Issues:
+//  [ ] Platform: Multi-viewport: Minimized windows seems to break mouse wheel events (at least under Windows).
+//  [x] Platform: IME support. Position somehow broken in SDL3 + app needs to call 'SDL_SetHint(SDL_HINT_IME_SHOW_UI, "1");' before SDL_CreateWindow()!.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_sdlgpu3.cpp b/backends/imgui_impl_sdlgpu3.cpp
index 975fcef..b64bbd5 100644
--- a/backends/imgui_impl_sdlgpu3.cpp
+++ b/backends/imgui_impl_sdlgpu3.cpp

@@ -5,6 +5,7 @@
 //  [X] Renderer: User texture binding. Use 'SDL_GPUTexture*' as texture identifier. Read the FAQ about ImTextureID/ImTextureRef! **IMPORTANT** Before 2025/08/08, ImTextureID was a reference to a SDL_GPUTextureSamplerBinding struct.
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // The aim of imgui_impl_sdlgpu3.h/.cpp is to be usable in your engine without any modification.
 // IF YOU FEEL YOU NEED TO MAKE ANY CHANGE TO THIS CODE, please share them and your feedback at https://github.com/ocornut/imgui/
@@ -22,6 +23,7 @@
 //   Calling the function is MANDATORY, otherwise the ImGui will not upload neither the vertex nor the index buffer for the GPU. See imgui_impl_sdlgpu3.cpp for more info.
 
 // CHANGELOG
+//  2026-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2025-11-26: macOS version can use MSL shaders in order to support macOS 10.14+ (vs Metallib shaders requiring macOS 14+). Requires calling SDL_CreateGPUDevice() with SDL_GPU_SHADERFORMAT_MSL.
 //  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-08-20: Added ImGui_ImplSDLGPU3_InitInfo::SwapchainComposition and ImGui_ImplSDLGPU3_InitInfo::PresentMode to configure how secondary viewports are created.
@@ -641,6 +643,9 @@
     if (bd->Pipeline)           { SDL_ReleaseGPUGraphicsPipeline(v->Device, bd->Pipeline); bd->Pipeline = nullptr; }
 }
 
+static void ImGui_ImplSDLGPU3_InitMultiViewportSupport();
+static void ImGui_ImplSDLGPU3_ShutdownMultiViewportSupport();
+
 bool ImGui_ImplSDLGPU3_Init(ImGui_ImplSDLGPU3_InitInfo* info)
 {
     ImGuiIO& io = ImGui::GetIO();
@@ -653,12 +658,15 @@
     io.BackendRendererName = "imgui_impl_sdlgpu3";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
     io.BackendFlags |= ImGuiBackendFlags_RendererHasTextures;   // We can honor ImGuiPlatformIO::Textures[] requests during render.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)
 
     IM_ASSERT(info->Device != nullptr);
     IM_ASSERT(info->ColorTargetFormat != SDL_GPU_TEXTUREFORMAT_INVALID);
 
     bd->InitInfo = *info;
 
+    ImGui_ImplSDLGPU3_InitMultiViewportSupport();
+
     return true;
 }
 
@@ -669,11 +677,12 @@
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
+    ImGui_ImplSDLGPU3_ShutdownMultiViewportSupport();
     ImGui_ImplSDLGPU3_DestroyDeviceObjects();
 
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures);
+    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
     platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
@@ -687,4 +696,76 @@
         ImGui_ImplSDLGPU3_CreateDeviceObjects();
 }
 
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+static void ImGui_ImplSDLGPU3_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDLGPU3_Data* data = ImGui_ImplSDLGPU3_GetBackendData();
+    SDL_Window* window = SDL_GetWindowFromID((SDL_WindowID)(intptr_t)viewport->PlatformHandle);
+    SDL_ClaimWindowForGPUDevice(data->InitInfo.Device, window);
+    SDL_SetGPUSwapchainParameters(data->InitInfo.Device, window, data->InitInfo.SwapchainComposition, data->InitInfo.PresentMode);
+    viewport->RendererUserData = (void*)1;
+}
+
+static void ImGui_ImplSDLGPU3_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplSDLGPU3_Data* data = ImGui_ImplSDLGPU3_GetBackendData();
+    SDL_Window* window = SDL_GetWindowFromID((SDL_WindowID)(intptr_t)viewport->PlatformHandle);
+
+    ImDrawData* draw_data = viewport->DrawData;
+
+    SDL_GPUCommandBuffer* command_buffer = SDL_AcquireGPUCommandBuffer(data->InitInfo.Device);
+
+    SDL_GPUTexture* swapchain_texture;
+    SDL_AcquireGPUSwapchainTexture(command_buffer, window, &swapchain_texture, nullptr, nullptr);
+
+    if (swapchain_texture != nullptr)
+    {
+        ImGui_ImplSDLGPU3_PrepareDrawData(draw_data, command_buffer); // FIXME-OPT: Not optimal, may this be done earlier?
+        SDL_GPUColorTargetInfo target_info = {};
+        target_info.texture = swapchain_texture;
+        target_info.clear_color = SDL_FColor{ 0.0f,0.0f,0.0f,1.0f };
+        target_info.load_op = SDL_GPU_LOADOP_CLEAR;
+        target_info.store_op = SDL_GPU_STOREOP_STORE;
+        target_info.mip_level = 0;
+        target_info.layer_or_depth_plane = 0;
+        target_info.cycle = false;
+        SDL_GPURenderPass* render_pass = SDL_BeginGPURenderPass(command_buffer, &target_info, 1, nullptr);
+        ImGui_ImplSDLGPU3_RenderDrawData(draw_data, command_buffer, render_pass);
+        SDL_EndGPURenderPass(render_pass);
+    }
+
+    SDL_SubmitGPUCommandBuffer(command_buffer);
+}
+
+static void ImGui_ImplSDLGPU3_DestroyWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplSDLGPU3_Data* data = ImGui_ImplSDLGPU3_GetBackendData();
+    if (viewport->RendererUserData)
+    {
+        SDL_Window* window = SDL_GetWindowFromID((SDL_WindowID)(intptr_t)viewport->PlatformHandle);
+        SDL_ReleaseWindowFromGPUDevice(data->InitInfo.Device, window);
+    }
+    viewport->RendererUserData = nullptr;
+}
+
+static void ImGui_ImplSDLGPU3_InitMultiViewportSupport()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Renderer_RenderWindow = ImGui_ImplSDLGPU3_RenderWindow;
+    platform_io.Renderer_CreateWindow = ImGui_ImplSDLGPU3_CreateWindow;
+    platform_io.Renderer_DestroyWindow = ImGui_ImplSDLGPU3_DestroyWindow;
+}
+
+static void ImGui_ImplSDLGPU3_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
+//-----------------------------------------------------------------------------
+
 #endif // #ifndef IMGUI_DISABLE

diff --git a/backends/imgui_impl_sdlgpu3.h b/backends/imgui_impl_sdlgpu3.h
index 1c73dfd..fe66433 100644
--- a/backends/imgui_impl_sdlgpu3.h
+++ b/backends/imgui_impl_sdlgpu3.h

@@ -5,6 +5,7 @@
 //  [X] Renderer: User texture binding. Use 'SDL_GPUTexture*' as texture identifier. Read the FAQ about ImTextureID/ImTextureRef! **IMPORTANT** Before 2025/08/08, ImTextureID was a reference to a SDL_GPUTextureSamplerBinding struct.
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
+//  [X] Renderer: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // The aim of imgui_impl_sdlgpu3.h/.cpp is to be usable in your engine without any modification.
 // IF YOU FEEL YOU NEED TO MAKE ANY CHANGE TO THIS CODE, please share them and your feedback at https://github.com/ocornut/imgui/

diff --git a/backends/imgui_impl_sdlrenderer2.cpp b/backends/imgui_impl_sdlrenderer2.cpp
index e03d131..c923058 100644
--- a/backends/imgui_impl_sdlrenderer2.cpp
+++ b/backends/imgui_impl_sdlrenderer2.cpp

@@ -14,6 +14,8 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
+// Missing features:
+//  [ ] Renderer: Multi-viewport support (multiple windows).
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_sdlrenderer2.h b/backends/imgui_impl_sdlrenderer2.h
index 860e955..ca49786 100644
--- a/backends/imgui_impl_sdlrenderer2.h
+++ b/backends/imgui_impl_sdlrenderer2.h

@@ -14,6 +14,8 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
+// Missing features:
+//  [ ] Renderer: Multi-viewport support (multiple windows).
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_sdlrenderer3.cpp b/backends/imgui_impl_sdlrenderer3.cpp
index 38a4383..64b6c5e 100644
--- a/backends/imgui_impl_sdlrenderer3.cpp
+++ b/backends/imgui_impl_sdlrenderer3.cpp

@@ -14,6 +14,8 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
+// Missing features:
+//  [ ] Renderer: Multi-viewport support (multiple windows).
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_sdlrenderer3.h b/backends/imgui_impl_sdlrenderer3.h
index f5f53b9..4815503 100644
--- a/backends/imgui_impl_sdlrenderer3.h
+++ b/backends/imgui_impl_sdlrenderer3.h

@@ -14,6 +14,8 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
+// Missing features:
+//  [ ] Renderer: Multi-viewport support (multiple windows).
 
 // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_vulkan.cpp b/backends/imgui_impl_vulkan.cpp
index c3a3049..0e4fb48 100644
--- a/backends/imgui_impl_vulkan.cpp
+++ b/backends/imgui_impl_vulkan.cpp

@@ -6,6 +6,7 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
+//  [x] Renderer: Multi-viewport / platform windows. With issues (flickering when creating a new viewport).
 
 // The aim of imgui_impl_vulkan.h/.cpp is to be usable in your engine without any modification.
 // IF YOU FEEL YOU NEED TO MAKE ANY CHANGE TO THIS CODE, please share them and your feedback at https://github.com/ocornut/imgui/
@@ -27,14 +28,17 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2025-09-26: [Helpers] *BREAKING CHANGE*: Vulkan: Helper ImGui_ImplVulkanH_DestroyWindow() does not call vkDestroySurfaceKHR(): as surface is created by caller of ImGui_ImplVulkanH_CreateOrResizeWindow(), it is more consistent that we don't destroy it. (#9163)
 //  2026-01-05: [Helpers] *BREAKING CHANGE*: Vulkan: Helper for creating render pass uses ImGui_ImplVulkanH_Window::AttachmentDesc to create render pass. Removed ClearEnabled. (#9152)
 //  2025-11-24: [Helpers] Vulkan: Helper for creating a swap-chain (used by examples and multi-viewports) selects VkSwapchainCreateInfoKHR's compositeAlpha based on cap.supportedCompositeAlpha. (#8784)
+//  2025-11-13: [Docking] Handle viewport surface creation failure without crashing. (#9068)
 //  2025-10-15: Vulkan: Added IMGUI_IMPL_VULKAN_VOLK_FILENAME to configure path to volk.h header. (#9008)
 //  2025-09-26: *BREAKING CHANGE*: moved some fields in ImGui_ImplVulkan_InitInfo: init_info.RenderPass --> init_info.PipelineInfoMain.RenderPass, init_info.Subpass --> init_info.PipelineInfoMain.Subpass, init_info.MSAASamples --> init_info.PipelineInfoMain.MSAASamples, init_info.PipelineRenderingCreateInfo --> init_info.PipelineInfoMain.PipelineRenderingCreateInfo.
 //  2025-09-26: *BREAKING CHANGE*: renamed ImGui_ImplVulkan_MainPipelineCreateInfo to ImGui_ImplVulkan_PipelineInfo. Introduced very recently so shouldn't affect many users.
 //  2025-09-26: [Helpers] *BREAKING CHANGE*: Helper ImGui_ImplVulkanH_CreateOrResizeWindow() added a VkImageUsageFlags image_usage` argument, default to VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT if 0.
 //  2025-09-26: Vulkan: Added a way to customize shaders by filling ImGui_ImplVulkan_InitInfo::CustomShaderVertCreateInfo/CustomShaderFragCreateInfo. (#8585)
+//  2025-09-22: [Docking] Added ImGui_ImplVulkanH_GetWindowDataFromViewport() accessor/helper. (#8946, #8940)
 //  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-09-04: Vulkan: Added ImGui_ImplVulkan_CreateMainPipeline(). (#8110, #8111)
 //  2025-07-27: Vulkan: Fixed texture update corruption introduced on 2025-06-11. (#8801, #8755, #8840)
@@ -133,6 +137,7 @@
 void ImGui_ImplVulkan_DestroyWindowRenderBuffers(VkDevice device, ImGui_ImplVulkan_WindowRenderBuffers* buffers, const VkAllocationCallbacks* allocator);
 void ImGui_ImplVulkanH_DestroyFrame(VkDevice device, ImGui_ImplVulkanH_Frame* fd, const VkAllocationCallbacks* allocator);
 void ImGui_ImplVulkanH_DestroyFrameSemaphores(VkDevice device, ImGui_ImplVulkanH_FrameSemaphores* fsd, const VkAllocationCallbacks* allocator);
+void ImGui_ImplVulkanH_DestroyAllViewportsRenderBuffers(VkDevice device, const VkAllocationCallbacks* allocator);
 void ImGui_ImplVulkanH_CreateWindowSwapChain(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, const VkAllocationCallbacks* allocator, int w, int h, uint32_t min_image_count, VkImageUsageFlags image_usage);
 void ImGui_ImplVulkanH_CreateWindowCommandBuffers(VkPhysicalDevice physical_device, VkDevice device, ImGui_ImplVulkanH_Window* wd, uint32_t queue_family, const VkAllocationCallbacks* allocator);
 
@@ -149,15 +154,18 @@
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkAllocateCommandBuffers) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkAllocateDescriptorSets) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkAllocateMemory) \
+    IMGUI_VULKAN_FUNC_MAP_MACRO(vkAcquireNextImageKHR) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkBeginCommandBuffer) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkBindBufferMemory) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkBindImageMemory) \
+    IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdBeginRenderPass) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdBindDescriptorSets) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdBindIndexBuffer) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdBindPipeline) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdBindVertexBuffers) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdCopyBufferToImage) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdDrawIndexed) \
+    IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdEndRenderPass) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdPipelineBarrier) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdPushConstants) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkCmdSetScissor) \
@@ -209,8 +217,10 @@
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkGetPhysicalDeviceSurfaceCapabilitiesKHR) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkGetPhysicalDeviceSurfaceFormatsKHR) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkGetPhysicalDeviceSurfacePresentModesKHR) \
+    IMGUI_VULKAN_FUNC_MAP_MACRO(vkGetPhysicalDeviceSurfaceSupportKHR) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkGetSwapchainImagesKHR) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkMapMemory) \
+    IMGUI_VULKAN_FUNC_MAP_MACRO(vkQueuePresentKHR) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkQueueSubmit) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkQueueWaitIdle) \
     IMGUI_VULKAN_FUNC_MAP_MACRO(vkResetCommandPool) \
@@ -261,6 +271,20 @@
     ImGui_ImplVulkan_Texture() { memset((void*)this, 0, sizeof(*this)); }
 };
 
+// For multi-viewport support:
+// Helper structure we store in the void* RendererUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGui_ImplVulkan_ViewportData
+{
+    ImGui_ImplVulkanH_Window                Window;                 // Used by secondary viewports only
+    ImGui_ImplVulkan_WindowRenderBuffers    RenderBuffers;          // Used by all viewports
+    bool                                    WindowOwned;
+    bool                                    SwapChainNeedRebuild;   // Flag when viewport swapchain resized in the middle of processing a frame
+    bool                                    SwapChainSuboptimal;    // Flag when VK_SUBOPTIMAL_KHR was returned.
+
+    ImGui_ImplVulkan_ViewportData() { WindowOwned = SwapChainNeedRebuild = SwapChainSuboptimal = false; memset((void*)&RenderBuffers, 0, sizeof(RenderBuffers)); }
+    ~ImGui_ImplVulkan_ViewportData() { }
+};
+
 // Vulkan data
 struct ImGui_ImplVulkan_Data
 {
@@ -271,6 +295,7 @@
     VkDescriptorSetLayout       DescriptorSetLayout;
     VkPipelineLayout            PipelineLayout;
     VkPipeline                  Pipeline;               // pipeline for main render pass (created by app)
+    VkPipeline                  PipelineForViewports;   // pipeline for secondary viewports (created by backend)
     VkShaderModule              ShaderModuleVert;
     VkShaderModule              ShaderModuleFrag;
     VkDescriptorPool            DescriptorPool;
@@ -296,6 +321,10 @@
 // SHADERS
 //-----------------------------------------------------------------------------
 
+// Forward Declarations
+static void ImGui_ImplVulkan_InitMultiViewportSupport();
+static void ImGui_ImplVulkan_ShutdownMultiViewportSupport();
+
 // backends/vulkan/glsl_shader.vert, compiled with:
 // # glslangValidator -V -x -o glsl_shader.vert.u32 glsl_shader.vert
 /*
@@ -540,8 +569,10 @@
     if (pipeline == VK_NULL_HANDLE)
         pipeline = bd->Pipeline;
 
-    // Allocate array to store enough vertex/index buffers
-    ImGui_ImplVulkan_WindowRenderBuffers* wrb = &bd->MainWindowRenderBuffers;
+    // Allocate array to store enough vertex/index buffers. Each unique viewport gets its own storage.
+    ImGui_ImplVulkan_ViewportData* viewport_renderer_data = (ImGui_ImplVulkan_ViewportData*)draw_data->OwnerViewport->RendererUserData;
+    IM_ASSERT(viewport_renderer_data != nullptr);
+    ImGui_ImplVulkan_WindowRenderBuffers* wrb = &viewport_renderer_data->RenderBuffers;
     if (wrb->FrameRenderBuffers.Size == 0)
     {
         wrb->Index = 0;
@@ -1181,7 +1212,7 @@
 {
     ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
     ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
-    ImGui_ImplVulkan_DestroyWindowRenderBuffers(v->Device, &bd->MainWindowRenderBuffers, v->Allocator);
+    ImGui_ImplVulkanH_DestroyAllViewportsRenderBuffers(v->Device, v->Allocator);
 
     // Destroy all textures
     for (ImTextureData* tex : ImGui::GetPlatformIO().Textures)
@@ -1196,6 +1227,7 @@
     if (bd->DescriptorSetLayout)  { vkDestroyDescriptorSetLayout(v->Device, bd->DescriptorSetLayout, v->Allocator); bd->DescriptorSetLayout = VK_NULL_HANDLE; }
     if (bd->PipelineLayout)       { vkDestroyPipelineLayout(v->Device, bd->PipelineLayout, v->Allocator); bd->PipelineLayout = VK_NULL_HANDLE; }
     if (bd->Pipeline)             { vkDestroyPipeline(v->Device, bd->Pipeline, v->Allocator); bd->Pipeline = VK_NULL_HANDLE; }
+    if (bd->PipelineForViewports) { vkDestroyPipeline(v->Device, bd->PipelineForViewports, v->Allocator); bd->PipelineForViewports = VK_NULL_HANDLE; }
     if (bd->DescriptorPool)       { vkDestroyDescriptorPool(v->Device, bd->DescriptorPool, v->Allocator); bd->DescriptorPool = VK_NULL_HANDLE; }
 }
 
@@ -1288,6 +1320,7 @@
     io.BackendRendererName = "imgui_impl_vulkan";
     io.BackendFlags |= ImGuiBackendFlags_RendererHasVtxOffset;  // We can honor the ImDrawCmd::VtxOffset field, allowing for large meshes.
     io.BackendFlags |= ImGuiBackendFlags_RendererHasTextures;   // We can honor ImGuiPlatformIO::Textures[] requests during render.
+    io.BackendFlags |= ImGuiBackendFlags_RendererHasViewports;  // We can create multi-viewports on the Renderer side (optional)
 
     // Sanity checks
     IM_ASSERT(info->Instance != VK_NULL_HANDLE);
@@ -1301,7 +1334,7 @@
     else
         IM_ASSERT(info->DescriptorPoolSize > 0);
     if (info->UseDynamicRendering)
-        IM_ASSERT(info->PipelineInfoMain.RenderPass == VK_NULL_HANDLE);
+        IM_ASSERT(info->PipelineInfoMain.RenderPass == VK_NULL_HANDLE && info->PipelineInfoForViewports.RenderPass == VK_NULL_HANDLE);
 
     bd->VulkanInitInfo = *info;
 
@@ -1312,6 +1345,12 @@
     if (!ImGui_ImplVulkan_CreateDeviceObjects())
         IM_ASSERT(0 && "ImGui_ImplVulkan_CreateDeviceObjects() failed!"); // <- Can't be hit yet.
 
+    // Our render function expect RendererUserData to be storing the window render buffer we need (for the main viewport we won't use ->Window)
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    main_viewport->RendererUserData = IM_NEW(ImGui_ImplVulkan_ViewportData)();
+
+    ImGui_ImplVulkan_InitMultiViewportSupport();
+
     return true;
 }
 
@@ -1322,11 +1361,21 @@
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
+    // First destroy objects in all viewports
     ImGui_ImplVulkan_DestroyDeviceObjects();
 
+    // Manually delete main viewport render data in-case we haven't initialized for viewports
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    if (ImGui_ImplVulkan_ViewportData* vd = (ImGui_ImplVulkan_ViewportData*)main_viewport->RendererUserData)
+        IM_DELETE(vd);
+    main_viewport->RendererUserData = nullptr;
+
+    // Clean up windows
+    ImGui_ImplVulkan_ShutdownMultiViewportSupport();
+
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures);
+    io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
     platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
@@ -1345,10 +1394,12 @@
     if (bd->VulkanInitInfo.MinImageCount == min_image_count)
         return;
 
+    IM_ASSERT(0); // FIXME-VIEWPORT: Unsupported. Need to recreate all swap chains!
     ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
     VkResult err = vkDeviceWaitIdle(v->Device);
     check_vk_result(err);
-    ImGui_ImplVulkan_DestroyWindowRenderBuffers(v->Device, &bd->MainWindowRenderBuffers, v->Allocator);
+    ImGui_ImplVulkanH_DestroyAllViewportsRenderBuffers(v->Device, v->Allocator);
+
     bd->VulkanInitInfo.MinImageCount = min_image_count;
 }
 
@@ -1625,8 +1676,6 @@
     wd->ImageCount = 0;
     if (wd->RenderPass)
         vkDestroyRenderPass(device, wd->RenderPass, allocator);
-    if (wd->Pipeline)
-        vkDestroyPipeline(device, wd->Pipeline, allocator);
 
     // If min image count was not specified, request different count of images dependent on selected present mode
     if (min_image_count == 0)
@@ -1871,7 +1920,6 @@
         ImGui_ImplVulkanH_DestroyFrameSemaphores(device, &wd->FrameSemaphores[i], allocator);
     wd->Frames.clear();
     wd->FrameSemaphores.clear();
-    vkDestroyPipeline(device, wd->Pipeline, allocator);
     vkDestroyRenderPass(device, wd->RenderPass, allocator);
     vkDestroySwapchainKHR(device, wd->Swapchain, allocator);
     wd->RenderPass = VK_NULL_HANDLE;
@@ -1901,6 +1949,333 @@
     fsd->ImageAcquiredSemaphore = fsd->RenderCompleteSemaphore = VK_NULL_HANDLE;
 }
 
+void ImGui_ImplVulkanH_DestroyAllViewportsRenderBuffers(VkDevice device, const VkAllocationCallbacks* allocator)
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int n = 0; n < platform_io.Viewports.Size; n++)
+        if (ImGui_ImplVulkan_ViewportData* vd = (ImGui_ImplVulkan_ViewportData*)platform_io.Viewports[n]->RendererUserData)
+            ImGui_ImplVulkan_DestroyWindowRenderBuffers(device, &vd->RenderBuffers, allocator);
+}
+
+ImGui_ImplVulkanH_Window* ImGui_ImplVulkanH_GetWindowDataFromViewport(ImGuiViewport* viewport)
+{
+    ImGui_ImplVulkan_ViewportData* vd = (ImGui_ImplVulkan_ViewportData*)viewport->RendererUserData;
+    return vd ? &vd->Window : nullptr;
+}
+
+//--------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+static void ImGui_ImplVulkan_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_ViewportData* vd = IM_NEW(ImGui_ImplVulkan_ViewportData)();
+    ImGui_ImplVulkanH_Window* wd = &vd->Window;
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+
+    // Create surface
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    VkResult err = (VkResult)platform_io.Platform_CreateVkSurface(viewport, (ImU64)v->Instance, (const void*)v->Allocator, (ImU64*)&wd->Surface);
+    check_vk_result(err);
+    
+    // Check if surface creation failed
+    if (err != VK_SUCCESS || wd->Surface == VK_NULL_HANDLE)
+    {
+        IM_DELETE(vd);
+        return;
+    }
+
+    // Check for WSI support
+    VkBool32 res;
+    vkGetPhysicalDeviceSurfaceSupportKHR(v->PhysicalDevice, v->QueueFamily, wd->Surface, &res);
+    if (res != VK_TRUE)
+    {
+        vkDestroySurfaceKHR(v->Instance, wd->Surface, v->Allocator); // Error: no WSI support on physical device, clean up and return
+        IM_DELETE(vd);
+        return;
+    }
+    viewport->RendererUserData = vd;
+
+    // Select Surface Format
+    ImGui_ImplVulkan_PipelineInfo* pipeline_info = &v->PipelineInfoForViewports;
+    ImVector<VkFormat> requestSurfaceImageFormats;
+#ifdef IMGUI_IMPL_VULKAN_HAS_DYNAMIC_RENDERING
+    for (uint32_t n = 0; n < pipeline_info->PipelineRenderingCreateInfo.colorAttachmentCount; n++)
+        requestSurfaceImageFormats.push_back(pipeline_info->PipelineRenderingCreateInfo.pColorAttachmentFormats[n]);
+#endif
+    const VkFormat defaultFormats[] = { VK_FORMAT_B8G8R8A8_UNORM, VK_FORMAT_R8G8B8A8_UNORM, VK_FORMAT_B8G8R8_UNORM, VK_FORMAT_R8G8B8_UNORM };
+    for (VkFormat format : defaultFormats)
+        requestSurfaceImageFormats.push_back(format);
+
+    const VkColorSpaceKHR requestSurfaceColorSpace = VK_COLORSPACE_SRGB_NONLINEAR_KHR;
+    wd->SurfaceFormat = ImGui_ImplVulkanH_SelectSurfaceFormat(v->PhysicalDevice, wd->Surface, requestSurfaceImageFormats.Data, (size_t)requestSurfaceImageFormats.Size, requestSurfaceColorSpace);
+
+    // Select Present Mode
+    // FIXME-VULKAN: Even thought mailbox seems to get us maximum framerate with a single window, it halves framerate with a second window etc. (w/ Nvidia and SDK 1.82.1)
+    VkPresentModeKHR present_modes[] = { VK_PRESENT_MODE_MAILBOX_KHR, VK_PRESENT_MODE_IMMEDIATE_KHR, VK_PRESENT_MODE_FIFO_KHR };
+    wd->PresentMode = ImGui_ImplVulkanH_SelectPresentMode(v->PhysicalDevice, wd->Surface, &present_modes[0], IM_COUNTOF(present_modes));
+    //printf("[vulkan] Secondary window selected PresentMode = %d\n", wd->PresentMode);
+
+    // Create SwapChain, RenderPass, Framebuffer, etc.
+    wd->UseDynamicRendering = v->UseDynamicRendering;
+    wd->AttachmentDesc.loadOp = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? VK_ATTACHMENT_LOAD_OP_DONT_CARE : VK_ATTACHMENT_LOAD_OP_CLEAR;
+    ImGui_ImplVulkanH_CreateOrResizeWindow(v->Instance, v->PhysicalDevice, v->Device, wd, v->QueueFamily, v->Allocator, (int)viewport->Size.x, (int)viewport->Size.y, v->MinImageCount, pipeline_info->SwapChainImageUsage);
+    vd->WindowOwned = true;
+
+    // Create pipeline (shared by all secondary viewports)
+    if (bd->PipelineForViewports == VK_NULL_HANDLE)
+    {
+#ifdef IMGUI_IMPL_VULKAN_HAS_DYNAMIC_RENDERING
+        if (wd->UseDynamicRendering)
+        {
+            pipeline_info->PipelineRenderingCreateInfo.sType = VK_STRUCTURE_TYPE_PIPELINE_RENDERING_CREATE_INFO;
+            pipeline_info->PipelineRenderingCreateInfo.colorAttachmentCount = 1;
+            pipeline_info->PipelineRenderingCreateInfo.pColorAttachmentFormats = &wd->SurfaceFormat.format;
+        }
+        else
+        {
+            pipeline_info->RenderPass = wd->RenderPass;
+        }
+#endif
+        bd->PipelineForViewports = ImGui_ImplVulkan_CreatePipeline(v->Device, v->Allocator, VK_NULL_HANDLE, &v->PipelineInfoForViewports);
+    }
+}
+
+static void ImGui_ImplVulkan_DestroyWindow(ImGuiViewport* viewport)
+{
+    // The main viewport (owned by the application) will always have RendererUserData == 0 since we didn't create the data for it.
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    if (ImGui_ImplVulkan_ViewportData* vd = (ImGui_ImplVulkan_ViewportData*)viewport->RendererUserData)
+    {
+        ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+        if (vd->WindowOwned)
+        {
+            ImGui_ImplVulkanH_DestroyWindow(v->Instance, v->Device, &vd->Window, v->Allocator);
+            vkDestroySurfaceKHR(v->Instance, vd->Window.Surface, v->Allocator);
+        }
+        ImGui_ImplVulkan_DestroyWindowRenderBuffers(v->Device, &vd->RenderBuffers, v->Allocator);
+        IM_DELETE(vd);
+    }
+    viewport->RendererUserData = nullptr;
+}
+
+static void ImGui_ImplVulkan_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_ViewportData* vd = (ImGui_ImplVulkan_ViewportData*)viewport->RendererUserData;
+    if (vd == nullptr) // This is nullptr for the main viewport (which is left to the user/app to handle)
+        return;
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+    ImGui_ImplVulkanH_Window* wd = &vd->Window;
+    wd->AttachmentDesc.loadOp = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? VK_ATTACHMENT_LOAD_OP_DONT_CARE : VK_ATTACHMENT_LOAD_OP_CLEAR;
+    ImGui_ImplVulkanH_CreateOrResizeWindow(v->Instance, v->PhysicalDevice, v->Device, &vd->Window, v->QueueFamily, v->Allocator, (int)size.x, (int)size.y, v->MinImageCount, v->PipelineInfoForViewports.SwapChainImageUsage);
+}
+
+static void ImGui_ImplVulkan_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_ViewportData* vd = (ImGui_ImplVulkan_ViewportData*)viewport->RendererUserData;
+    if (vd == nullptr)
+        return;
+    ImGui_ImplVulkanH_Window* wd = &vd->Window;
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+    VkResult err;
+
+    if (vd->SwapChainNeedRebuild || vd->SwapChainSuboptimal)
+    {
+        ImGui_ImplVulkanH_CreateOrResizeWindow(v->Instance, v->PhysicalDevice, v->Device, wd, v->QueueFamily, v->Allocator, (int)viewport->Size.x, (int)viewport->Size.y, v->MinImageCount, v->PipelineInfoForViewports.SwapChainImageUsage);
+        vd->SwapChainNeedRebuild = vd->SwapChainSuboptimal = false;
+    }
+
+    ImGui_ImplVulkanH_Frame* fd = nullptr;
+    ImGui_ImplVulkanH_FrameSemaphores* fsd = &wd->FrameSemaphores[wd->SemaphoreIndex];
+    {
+        {
+            err = vkAcquireNextImageKHR(v->Device, wd->Swapchain, UINT64_MAX, fsd->ImageAcquiredSemaphore, VK_NULL_HANDLE, &wd->FrameIndex);
+            if (err == VK_ERROR_OUT_OF_DATE_KHR)
+            {
+                vd->SwapChainNeedRebuild = true; // Since we are not going to swap this frame anyway, it's ok that recreation happens on next frame.
+                return;
+            }
+            if (err == VK_SUBOPTIMAL_KHR)
+                vd->SwapChainSuboptimal = true;
+            else
+                check_vk_result(err);
+            fd = &wd->Frames[wd->FrameIndex];
+        }
+        for (;;)
+        {
+            err = vkWaitForFences(v->Device, 1, &fd->Fence, VK_TRUE, 100);
+            if (err == VK_SUCCESS) break;
+            if (err == VK_TIMEOUT) continue;
+            check_vk_result(err);
+        }
+        {
+            err = vkResetCommandPool(v->Device, fd->CommandPool, 0);
+            check_vk_result(err);
+            VkCommandBufferBeginInfo info = {};
+            info.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO;
+            info.flags |= VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;
+            err = vkBeginCommandBuffer(fd->CommandBuffer, &info);
+            check_vk_result(err);
+        }
+        {
+            ImVec4 clear_color = ImVec4(0.0f, 0.0f, 0.0f, 1.0f);
+            memcpy(&wd->ClearValue.color.float32[0], &clear_color, 4 * sizeof(float));
+        }
+#ifdef IMGUI_IMPL_VULKAN_HAS_DYNAMIC_RENDERING
+        if (v->UseDynamicRendering)
+        {
+            // Transition swapchain image to a layout suitable for drawing.
+            VkImageMemoryBarrier barrier = {};
+            barrier.sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER;
+            barrier.dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+            barrier.oldLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR;
+            barrier.newLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+            barrier.image = fd->Backbuffer;
+            barrier.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
+            barrier.subresourceRange.levelCount = 1;
+            barrier.subresourceRange.layerCount = 1;
+            vkCmdPipelineBarrier(fd->CommandBuffer, VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT | VK_PIPELINE_STAGE_NONE, VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT, 0, 0, nullptr, 0, nullptr, 1, &barrier);
+
+            VkRenderingAttachmentInfo attachmentInfo = {};
+            attachmentInfo.sType = VK_STRUCTURE_TYPE_RENDERING_ATTACHMENT_INFO_KHR;
+            attachmentInfo.imageView = fd->BackbufferView;
+            attachmentInfo.imageLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+            attachmentInfo.resolveMode = VK_RESOLVE_MODE_NONE;
+            attachmentInfo.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
+            attachmentInfo.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
+            attachmentInfo.clearValue = wd->ClearValue;
+
+            VkRenderingInfo renderingInfo = {};
+            renderingInfo.sType = VK_STRUCTURE_TYPE_RENDERING_INFO_KHR;
+            renderingInfo.renderArea.extent.width = wd->Width;
+            renderingInfo.renderArea.extent.height = wd->Height;
+            renderingInfo.layerCount = 1;
+            renderingInfo.viewMask = 0;
+            renderingInfo.colorAttachmentCount = 1;
+            renderingInfo.pColorAttachments = &attachmentInfo;
+
+            ImGuiImplVulkanFuncs_vkCmdBeginRenderingKHR(fd->CommandBuffer, &renderingInfo);
+        }
+        else
+#endif
+        {
+            VkRenderPassBeginInfo info = {};
+            info.sType = VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO;
+            info.renderPass = wd->RenderPass;
+            info.framebuffer = fd->Framebuffer;
+            info.renderArea.extent.width = wd->Width;
+            info.renderArea.extent.height = wd->Height;
+            info.clearValueCount = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? 0 : 1;
+            info.pClearValues = (viewport->Flags & ImGuiViewportFlags_NoRendererClear) ? nullptr : &wd->ClearValue;
+            vkCmdBeginRenderPass(fd->CommandBuffer, &info, VK_SUBPASS_CONTENTS_INLINE);
+        }
+    }
+
+    ImGui_ImplVulkan_RenderDrawData(viewport->DrawData, fd->CommandBuffer, bd->PipelineForViewports);
+
+    {
+#ifdef IMGUI_IMPL_VULKAN_HAS_DYNAMIC_RENDERING
+        if (v->UseDynamicRendering)
+        {
+            ImGuiImplVulkanFuncs_vkCmdEndRenderingKHR(fd->CommandBuffer);
+
+            // Transition image to a layout suitable for presentation
+            VkImageMemoryBarrier barrier = {};
+            barrier.sType = VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER;
+            barrier.srcAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+            barrier.oldLayout = VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL;
+            barrier.newLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR;
+            barrier.image = fd->Backbuffer;
+            barrier.subresourceRange.aspectMask = VK_IMAGE_ASPECT_COLOR_BIT;
+            barrier.subresourceRange.levelCount = 1;
+            barrier.subresourceRange.layerCount = 1;
+            vkCmdPipelineBarrier(fd->CommandBuffer, VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT, VK_PIPELINE_STAGE_BOTTOM_OF_PIPE_BIT, 0, 0, nullptr, 0, nullptr, 1, &barrier);
+        }
+        else
+#endif
+        {
+            vkCmdEndRenderPass(fd->CommandBuffer);
+        }
+        {
+            VkPipelineStageFlags wait_stage = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
+            VkSubmitInfo info = {};
+            info.sType = VK_STRUCTURE_TYPE_SUBMIT_INFO;
+            info.waitSemaphoreCount = 1;
+            info.pWaitSemaphores = &fsd->ImageAcquiredSemaphore;
+            info.pWaitDstStageMask = &wait_stage;
+            info.commandBufferCount = 1;
+            info.pCommandBuffers = &fd->CommandBuffer;
+            info.signalSemaphoreCount = 1;
+            info.pSignalSemaphores = &fsd->RenderCompleteSemaphore;
+
+            err = vkEndCommandBuffer(fd->CommandBuffer);
+            check_vk_result(err);
+            err = vkResetFences(v->Device, 1, &fd->Fence);
+            check_vk_result(err);
+            err = vkQueueSubmit(v->Queue, 1, &info, fd->Fence);
+            check_vk_result(err);
+        }
+    }
+}
+
+static void ImGui_ImplVulkan_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
+    ImGui_ImplVulkan_ViewportData* vd = (ImGui_ImplVulkan_ViewportData*)viewport->RendererUserData;
+    if (vd == nullptr)
+        return;
+    ImGui_ImplVulkanH_Window* wd = &vd->Window;
+    ImGui_ImplVulkan_InitInfo* v = &bd->VulkanInitInfo;
+
+    if (vd->SwapChainNeedRebuild) // Frame data became invalid in the middle of rendering
+        return;
+
+    VkResult err;
+    uint32_t present_index = wd->FrameIndex;
+
+    ImGui_ImplVulkanH_FrameSemaphores* fsd = &wd->FrameSemaphores[wd->SemaphoreIndex];
+    VkPresentInfoKHR info = {};
+    info.sType = VK_STRUCTURE_TYPE_PRESENT_INFO_KHR;
+    info.waitSemaphoreCount = 1;
+    info.pWaitSemaphores = &fsd->RenderCompleteSemaphore;
+    info.swapchainCount = 1;
+    info.pSwapchains = &wd->Swapchain;
+    info.pImageIndices = &present_index;
+    err = vkQueuePresentKHR(v->Queue, &info);
+    if (err == VK_ERROR_OUT_OF_DATE_KHR)
+    {
+        vd->SwapChainNeedRebuild = true;
+        return;
+    }
+    if (err == VK_SUBOPTIMAL_KHR)
+        vd->SwapChainSuboptimal = true;
+    else
+        check_vk_result(err);
+    wd->SemaphoreIndex = (wd->SemaphoreIndex + 1) % wd->SemaphoreCount; // Now we can use the next set of semaphores
+}
+
+void ImGui_ImplVulkan_InitMultiViewportSupport()
+{
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    if (ImGui::GetIO().BackendFlags & ImGuiBackendFlags_PlatformHasViewports)
+        IM_ASSERT(platform_io.Platform_CreateVkSurface != nullptr && "Platform needs to setup the CreateVkSurface handler.");
+    platform_io.Renderer_CreateWindow = ImGui_ImplVulkan_CreateWindow;
+    platform_io.Renderer_DestroyWindow = ImGui_ImplVulkan_DestroyWindow;
+    platform_io.Renderer_SetWindowSize = ImGui_ImplVulkan_SetWindowSize;
+    platform_io.Renderer_RenderWindow = ImGui_ImplVulkan_RenderWindow;
+    platform_io.Renderer_SwapBuffers = ImGui_ImplVulkan_SwapBuffers;
+}
+
+void ImGui_ImplVulkan_ShutdownMultiViewportSupport()
+{
+    ImGui::DestroyPlatformWindows();
+}
+
 //-----------------------------------------------------------------------------
 
 #endif // #ifndef IMGUI_DISABLE

diff --git a/backends/imgui_impl_vulkan.h b/backends/imgui_impl_vulkan.h
index 5b3baf0..f840800 100644
--- a/backends/imgui_impl_vulkan.h
+++ b/backends/imgui_impl_vulkan.h

@@ -6,6 +6,7 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Texture updates support for dynamic font atlas (ImGuiBackendFlags_RendererHasTextures).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
+//  [x] Renderer: Multi-viewport / platform windows. With issues (flickering when creating a new viewport).
 
 // The aim of imgui_impl_vulkan.h/.cpp is to be usable in your engine without any modification.
 // IF YOU FEEL YOU NEED TO MAKE ANY CHANGE TO THIS CODE, please share them and your feedback at https://github.com/ocornut/imgui/
@@ -83,12 +84,18 @@
 // Specify settings to create pipeline and swapchain
 struct ImGui_ImplVulkan_PipelineInfo
 {
+    // For Main viewport only
     VkRenderPass                    RenderPass;                     // Ignored if using dynamic rendering
+
+    // For Main and Secondary viewports
     uint32_t                        Subpass;                        //
     VkSampleCountFlagBits           MSAASamples = {};               // 0 defaults to VK_SAMPLE_COUNT_1_BIT
 #ifdef IMGUI_IMPL_VULKAN_HAS_DYNAMIC_RENDERING
     VkPipelineRenderingCreateInfoKHR PipelineRenderingCreateInfo;   // Optional, valid if .sType == VK_STRUCTURE_TYPE_PIPELINE_RENDERING_CREATE_INFO_KHR
 #endif
+
+    // For Secondary viewports only (created/managed by backend)
+    VkImageUsageFlags               SwapChainImageUsage;            // Extra flags for vkCreateSwapchainKHR() calls for secondary viewports. We automatically add VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT. You can add e.g. VK_IMAGE_USAGE_TRANSFER_SRC_BIT if you need to capture from viewports.
 };
 
 // Initialization data, for ImGui_ImplVulkan_Init()
@@ -115,13 +122,14 @@
 
     // Pipeline
     ImGui_ImplVulkan_PipelineInfo   PipelineInfoMain;           // Infos for Main Viewport (created by app/user)
+    ImGui_ImplVulkan_PipelineInfo   PipelineInfoForViewports;   // Infos for Secondary Viewports (created by backend)
     //VkRenderPass                  RenderPass;                 // --> Since 2025/09/26: set 'PipelineInfoMain.RenderPass' instead
     //uint32_t                      Subpass;                    // --> Since 2025/09/26: set 'PipelineInfoMain.Subpass' instead
     //VkSampleCountFlagBits         MSAASamples;                // --> Since 2025/09/26: set 'PipelineInfoMain.MSAASamples' instead
     //VkPipelineRenderingCreateInfoKHR PipelineRenderingCreateInfo; // Since 2025/09/26: set 'PipelineInfoMain.PipelineRenderingCreateInfo' instead
 
     // (Optional) Dynamic Rendering
-    // Need to explicitly enable VK_KHR_dynamic_rendering extension to use this, even for Vulkan 1.3 + setup PipelineInfoMain.PipelineRenderingCreateInfo.
+    // Need to explicitly enable VK_KHR_dynamic_rendering extension to use this, even for Vulkan 1.3 + setup PipelineInfoMain.PipelineRenderingCreateInfo and PipelineInfoViewports.PipelineRenderingCreateInfo.
     bool                            UseDynamicRendering;
 
     // (Optional) Allocation, Debugging
@@ -203,6 +211,7 @@
 IMGUI_IMPL_API VkPhysicalDevice     ImGui_ImplVulkanH_SelectPhysicalDevice(VkInstance instance);
 IMGUI_IMPL_API uint32_t             ImGui_ImplVulkanH_SelectQueueFamilyIndex(VkPhysicalDevice physical_device);
 IMGUI_IMPL_API int                  ImGui_ImplVulkanH_GetMinImageCountFromPresentMode(VkPresentModeKHR present_mode);
+IMGUI_IMPL_API ImGui_ImplVulkanH_Window* ImGui_ImplVulkanH_GetWindowDataFromViewport(ImGuiViewport* viewport); // Access to Vulkan objects associated with a viewport (e.g to export a screenshot)
 
 // Helper structure to hold the data needed by one rendering frame
 // (Used by example's main.cpp. Used by multi-viewport features. Probably NOT used by your own engine/app.)
@@ -240,7 +249,6 @@
     int                     Height;
     VkSwapchainKHR          Swapchain;
     VkRenderPass            RenderPass;
-    VkPipeline              Pipeline;           // The window pipeline may uses a different VkRenderPass than the one passed in ImGui_ImplVulkan_InitInfo
     uint32_t                FrameIndex;         // Current frame being rendered to (0 <= FrameIndex < FrameInFlightCount)
     uint32_t                ImageCount;         // Number of simultaneous in-flight frames (returned by vkGetSwapchainImagesKHR, usually derived from min_image_count)
     uint32_t                SemaphoreCount;     // Number of simultaneous in-flight frames + 1, to be able to use it in vkAcquireNextImageKHR

diff --git a/backends/imgui_impl_wgpu.cpp b/backends/imgui_impl_wgpu.cpp
index e98e9f3..a8d3924 100644
--- a/backends/imgui_impl_wgpu.cpp
+++ b/backends/imgui_impl_wgpu.cpp

@@ -7,6 +7,8 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
 //  [X] Renderer: Texture updates support for dynamic font system (ImGuiBackendFlags_RendererHasTextures).
+// Missing features or Issues:
+//  [ ] Renderer: Multi-viewport support (multiple windows), useful for desktop.
 
 // Read imgui_impl_wgpu.h about how to use the IMGUI_IMPL_WEBGPU_BACKEND_WGPU or IMGUI_IMPL_WEBGPU_BACKEND_DAWN flags.
 

diff --git a/backends/imgui_impl_wgpu.h b/backends/imgui_impl_wgpu.h
index 5222345..c399668 100644
--- a/backends/imgui_impl_wgpu.h
+++ b/backends/imgui_impl_wgpu.h

@@ -17,6 +17,8 @@
 //  [X] Renderer: Large meshes support (64k+ vertices) even with 16-bit indices (ImGuiBackendFlags_RendererHasVtxOffset).
 //  [X] Renderer: Expose selected render state for draw callbacks to use. Access in '(ImGui_ImplXXXX_RenderState*)GetPlatformIO().Renderer_RenderState'.
 //  [X] Renderer: Texture updates support for dynamic font system (ImGuiBackendFlags_RendererHasTextures).
+// Missing features or Issues:
+//  [ ] Renderer: Multi-viewport support (multiple windows), useful for desktop.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/backends/imgui_impl_win32.cpp b/backends/imgui_impl_win32.cpp
index de92040..8d160b3 100644
--- a/backends/imgui_impl_win32.cpp
+++ b/backends/imgui_impl_win32.cpp

@@ -7,6 +7,7 @@
 //  [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy VK_* values are obsolete since 1.87 and not supported since 1.91.5]
 //  [X] Platform: Gamepad support.
 //  [X] Platform: Mouse cursor shape and visibility (ImGuiBackendFlags_HasMouseCursors). Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
@@ -21,14 +22,22 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2026-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
 //  2026-01-28: Inputs: Minor optimization not submitting gamepad input if packet number has not changed (reworked from 2025-09-23 attempt). (#9202, #8556)
+//  2026-01-26: [Docking] Fixed an issue from 1.90.5 where newly appearing windows that are not parented to the main viewport don't have task bar icon appear before the windows was explicited refocused. (#7354, #8669)
 //  2025-12-03: Inputs: handle WM_IME_CHAR/WM_IME_COMPOSITION messages to support Unicode inputs on MBCS (non-Unicode) Windows. (#9099, #3653, #5961)
 //  2025-10-19: Inputs: Revert previous change to allow for io.ClearInputKeys() on focus-out not losing gamepad state.
 //  2025-09-23: Inputs: Minor optimization not submitting gamepad input if packet number has not changed.
 //  2025-09-18: Call platform_io.ClearPlatformHandlers() on shutdown.
+//  2025-06-02: [Docking] WM_DPICHANGED also apply io.ConfigDpiScaleViewports for main viewport instead of letting it be done by application code.
 //  2025-04-30: Inputs: Fixed an issue where externally losing mouse capture (due to e.g. focus loss) would fail to claim it again the next subsequent click. (#8594)
+//  2025-03-26: [Docking] Viewports: fixed an issue when closing a window from the OS close button (with io.ConfigViewportsNoDecoration = false) while user code was discarding the 'bool* p_open = false' output from Begin(). Because we allowed the Win32 window to close early, Windows destroyed it and our imgui window became not visible even though user code was still submitting it.
 //  2025-03-10: When dealing with OEM keys, use scancodes instead of translated keycodes to choose ImGuiKey values. (#7136, #7201, #7206, #7306, #7670, #7672, #8468)
+//  2025-02-21: [Docking] WM_SETTINGCHANGE's SPI_SETWORKAREA message also triggers a refresh of monitor list. (#8415)
 //  2025-02-18: Added ImGuiMouseCursor_Wait and ImGuiMouseCursor_Progress mouse cursor support.
+//  2024-11-21: [Docking] Fixed a crash when multiple processes are running with multi-viewports, caused by misusage of GetProp(). (#8162, #8069)
+//  2024-10-28: [Docking] Rely on property stored inside HWND to retrieve context/viewport, should facilitate attempt to use this for parallel contexts. (#8069)
+//  2024-09-16: [Docking] Inputs: fixed an issue where a viewport destroyed while clicking would hog mouse tracking and temporary lead to incorrect update of HoveredWindow. (#7971)
 //  2024-07-08: Inputs: Fixed ImGuiMod_Super being mapped to VK_APPS instead of VK_LWIN||VK_RWIN. (#7768)
 //  2023-10-05: Inputs: Added support for extra ImGuiKey values: F13 to F24 function keys, app back/forward keys.
 //  2023-09-25: Inputs: Synthesize key-down event on key-up for VK_SNAPSHOT / ImGuiKey_PrintScreen as Windows doesn't emit it (same behavior as GLFW/SDL).
@@ -111,6 +120,11 @@
 #pragma GCC diagnostic ignored "-Wcast-function-type"       // warning: cast between incompatible function types (for loader)
 #endif
 
+// Forward Declarations
+static void ImGui_ImplWin32_InitMultiViewportSupport(bool platform_has_own_dc);
+static void ImGui_ImplWin32_ShutdownMultiViewportSupport();
+static void ImGui_ImplWin32_UpdateMonitors();
+
 struct ImGui_ImplWin32_Data
 {
     HWND                        hWnd;
@@ -121,6 +135,7 @@
     INT64                       TicksPerSecond;
     ImGuiMouseCursor            LastMouseCursor;
     UINT32                      KeyboardCodePage;
+    bool                        WantUpdateMonitors;
 
 #ifndef IMGUI_IMPL_WIN32_DISABLE_GAMEPAD
     bool                        HasGamepad;
@@ -176,6 +191,9 @@
     io.BackendPlatformName = "imgui_impl_win32";
     io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;         // We can honor GetMouseCursor() values (optional)
     io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;          // We can honor io.WantSetMousePos requests (optional, rarely used)
+    io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports;    // We can create multi-viewports on the Platform side (optional)
+    io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport; // We can call io.AddMouseViewportEvent() with correct data (optional)
+    io.BackendFlags |= ImGuiBackendFlags_HasParentViewport;       // We can honor viewport->ParentViewportId by applying the corresponding parent/child relationship at platform levle (optional)
 
     bd->hWnd = (HWND)hwnd;
     bd->TicksPerSecond = perf_frequency;
@@ -183,10 +201,17 @@
     bd->LastMouseCursor = ImGuiMouseCursor_COUNT;
     ImGui_ImplWin32_UpdateKeyboardCodePage(io);
 
+    // Update monitor a first time during init
+    ImGui_ImplWin32_UpdateMonitors();
+
     // Our mouse update function expect PlatformHandle to be filled for the main viewport
     ImGuiViewport* main_viewport = ImGui::GetMainViewport();
     main_viewport->PlatformHandle = main_viewport->PlatformHandleRaw = (void*)bd->hWnd;
-    IM_UNUSED(platform_has_own_dc); // Used in 'docking' branch
+
+    // Be aware that GetPropA()/SetPropA() may be accessed from other processes.
+    // So as we store a pointer in IMGUI_CONTEXT we need to make sure we only call GetPropA() on windows owned by our process.
+    ::SetPropA(bd->hWnd, "IMGUI_CONTEXT", ImGui::GetCurrentContext());
+    ImGui_ImplWin32_InitMultiViewportSupport(platform_has_own_dc);
 
     // Dynamically load XInput library
 #ifndef IMGUI_IMPL_WIN32_DISABLE_GAMEPAD
@@ -230,6 +255,9 @@
     ImGuiIO& io = ImGui::GetIO();
     ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
+    ::SetPropA(bd->hWnd, "IMGUI_CONTEXT", nullptr);
+    ImGui_ImplWin32_ShutdownMultiViewportSupport();
+
     // Unload XInput library
 #ifndef IMGUI_IMPL_WIN32_DISABLE_GAMEPAD
     if (bd->XInputDLL)
@@ -238,7 +266,7 @@
 
     io.BackendPlatformName = nullptr;
     io.BackendPlatformUserData = nullptr;
-    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad);
+    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad | ImGuiBackendFlags_PlatformHasViewports | ImGuiBackendFlags_HasMouseHoveredViewport | ImGuiBackendFlags_HasParentViewport);
     platform_io.ClearPlatformHandlers();
     IM_DELETE(bd);
 }
@@ -311,32 +339,69 @@
     io.AddKeyEvent(ImGuiMod_Super, IsVkDown(VK_LWIN) || IsVkDown(VK_RWIN));
 }
 
-static void ImGui_ImplWin32_UpdateMouseData(ImGuiIO& io)
+static ImGuiViewport* ImGui_ImplWin32_FindViewportByPlatformHandle(ImGuiPlatformIO& platform_io, HWND hwnd)
+{
+    // We cannot use ImGui::FindViewportByPlatformHandle() because it doesn't take a context.
+    // When called from ImGui_ImplWin32_WndProcHandler_PlatformWindow() we don't assume that context is bound.
+    //return ImGui::FindViewportByPlatformHandle((void*)hwnd);
+    for (ImGuiViewport* viewport : platform_io.Viewports)
+        if (viewport->PlatformHandle == hwnd)
+            return viewport;
+    return nullptr;
+}
+
+// This code supports multi-viewports (multiple OS Windows mapped into different Dear ImGui viewports)
+// Because of that, it is a little more complicated than your typical single-viewport binding code!
+static void ImGui_ImplWin32_UpdateMouseData(ImGuiIO& io, ImGuiPlatformIO& platform_io)
 {
     ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData(io);
     IM_ASSERT(bd->hWnd != 0);
 
+    POINT mouse_screen_pos;
+    bool has_mouse_screen_pos = ::GetCursorPos(&mouse_screen_pos) != 0;
+
     HWND focused_window = ::GetForegroundWindow();
-    const bool is_app_focused = (focused_window == bd->hWnd);
+    const bool is_app_focused = (focused_window && (focused_window == bd->hWnd || ::IsChild(focused_window, bd->hWnd) || ImGui_ImplWin32_FindViewportByPlatformHandle(platform_io, focused_window)));
     if (is_app_focused)
     {
         // (Optional) Set OS mouse position from Dear ImGui if requested (rarely used, only when io.ConfigNavMoveSetMousePos is enabled by user)
+        // When multi-viewports are enabled, all Dear ImGui positions are same as OS positions.
         if (io.WantSetMousePos)
         {
             POINT pos = { (int)io.MousePos.x, (int)io.MousePos.y };
-            if (::ClientToScreen(bd->hWnd, &pos))
-                ::SetCursorPos(pos.x, pos.y);
+            if ((io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) == 0)
+                ::ClientToScreen(focused_window, &pos);
+            ::SetCursorPos(pos.x, pos.y);
         }
 
         // (Optional) Fallback to provide mouse position when focused (WM_MOUSEMOVE already provides this when hovered or captured)
         // This also fills a short gap when clicking non-client area: WM_NCMOUSELEAVE -> modal OS move -> gap -> WM_NCMOUSEMOVE
-        if (!io.WantSetMousePos && bd->MouseTrackedArea == 0)
+        if (!io.WantSetMousePos && bd->MouseTrackedArea == 0 && has_mouse_screen_pos)
         {
-            POINT pos;
-            if (::GetCursorPos(&pos) && ::ScreenToClient(bd->hWnd, &pos))
-                io.AddMousePosEvent((float)pos.x, (float)pos.y);
+            // Single viewport mode: mouse position in client window coordinates (io.MousePos is (0,0) when the mouse is on the upper-left corner of the app window)
+            // (This is the position you can get with ::GetCursorPos() + ::ScreenToClient() or WM_MOUSEMOVE.)
+            // Multi-viewport mode: mouse position in OS absolute coordinates (io.MousePos is (0,0) when the mouse is on the upper-left of the primary monitor)
+            // (This is the position you can get with ::GetCursorPos() or WM_MOUSEMOVE + ::ClientToScreen(). In theory adding viewport->Pos to a client position would also be the same.)
+            POINT mouse_pos = mouse_screen_pos;
+            if (!(io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable))
+                ::ScreenToClient(bd->hWnd, &mouse_pos);
+            io.AddMousePosEvent((float)mouse_pos.x, (float)mouse_pos.y);
         }
     }
+
+    // (Optional) When using multiple viewports: call io.AddMouseViewportEvent() with the viewport the OS mouse cursor is hovering.
+    // If ImGuiBackendFlags_HasMouseHoveredViewport is not set by the backend, Dear imGui will ignore this field and infer the information using its flawed heuristic.
+    // - [X] Win32 backend correctly ignore viewports with the _NoInputs flag (here using ::WindowFromPoint with WM_NCHITTEST + HTTRANSPARENT in WndProc does that)
+    //       Some backend are not able to handle that correctly. If a backend report an hovered viewport that has the _NoInputs flag (e.g. when dragging a window
+    //       for docking, the viewport has the _NoInputs flag in order to allow us to find the viewport under), then Dear ImGui is forced to ignore the value reported
+    //       by the backend, and use its flawed heuristic to guess the viewport behind.
+    // - [X] Win32 backend correctly reports this regardless of another viewport behind focused and dragged from (we need this to find a useful drag and drop target).
+    ImGuiID mouse_viewport_id = 0;
+    if (has_mouse_screen_pos)
+        if (HWND hovered_hwnd = ::WindowFromPoint(mouse_screen_pos))
+            if (ImGuiViewport* viewport = ImGui_ImplWin32_FindViewportByPlatformHandle(platform_io, hovered_hwnd))
+                mouse_viewport_id = viewport->ID;
+    io.AddMouseViewportEvent(mouse_viewport_id);
 }
 
 // Gamepad navigation mapping
@@ -398,16 +463,50 @@
 #endif
 }
 
+static BOOL CALLBACK ImGui_ImplWin32_UpdateMonitors_EnumFunc(HMONITOR monitor, HDC, LPRECT, LPARAM)
+{
+    MONITORINFO info = {};
+    info.cbSize = sizeof(MONITORINFO);
+    if (!::GetMonitorInfo(monitor, &info))
+        return TRUE;
+    ImGuiPlatformMonitor imgui_monitor;
+    imgui_monitor.MainPos = ImVec2((float)info.rcMonitor.left, (float)info.rcMonitor.top);
+    imgui_monitor.MainSize = ImVec2((float)(info.rcMonitor.right - info.rcMonitor.left), (float)(info.rcMonitor.bottom - info.rcMonitor.top));
+    imgui_monitor.WorkPos = ImVec2((float)info.rcWork.left, (float)info.rcWork.top);
+    imgui_monitor.WorkSize = ImVec2((float)(info.rcWork.right - info.rcWork.left), (float)(info.rcWork.bottom - info.rcWork.top));
+    imgui_monitor.DpiScale = ImGui_ImplWin32_GetDpiScaleForMonitor(monitor);
+    imgui_monitor.PlatformHandle = (void*)monitor;
+    if (imgui_monitor.DpiScale <= 0.0f)
+        return TRUE; // Some accessibility applications are declaring virtual monitors with a DPI of 0, see #7902.
+    ImGuiPlatformIO& io = ImGui::GetPlatformIO();
+    if (info.dwFlags & MONITORINFOF_PRIMARY)
+        io.Monitors.push_front(imgui_monitor);
+    else
+        io.Monitors.push_back(imgui_monitor);
+    return TRUE;
+}
+
+static void ImGui_ImplWin32_UpdateMonitors()
+{
+    ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData();
+    ImGui::GetPlatformIO().Monitors.resize(0);
+    ::EnumDisplayMonitors(nullptr, nullptr, ImGui_ImplWin32_UpdateMonitors_EnumFunc, 0);
+    bd->WantUpdateMonitors = false;
+}
+
 void    ImGui_ImplWin32_NewFrame()
 {
     ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData();
     IM_ASSERT(bd != nullptr && "Context or backend not initialized? Did you call ImGui_ImplWin32_Init()?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     // Setup display size (every frame to accommodate for window resizing)
     RECT rect = { 0, 0, 0, 0 };
     ::GetClientRect(bd->hWnd, &rect);
     io.DisplaySize = ImVec2((float)(rect.right - rect.left), (float)(rect.bottom - rect.top));
+    if (bd->WantUpdateMonitors)
+        ImGui_ImplWin32_UpdateMonitors();
 
     // Setup time step
     INT64 current_time = 0;
@@ -416,7 +515,7 @@
     bd->Time = current_time;
 
     // Update OS mouse position
-    ImGui_ImplWin32_UpdateMouseData(io);
+    ImGui_ImplWin32_UpdateMouseData(io, platform_io);
 
     // Process workarounds for known Windows key handling issues
     ImGui_ImplWin32_ProcessKeyEventsWorkarounds(io);
@@ -621,6 +720,10 @@
 extern IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);                // Use ImGui::GetCurrentContext()
 extern IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandlerEx(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam, ImGuiIO& io); // Doesn't use ImGui::GetCurrentContext()
 
+#ifndef WM_DPICHANGED
+#define WM_DPICHANGED 0x02E0 // From Windows SDK 8.1+ headers
+#endif
+
 IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
 {
     // Most backends don't have silent checks like this one, but we need it because WndProc are called early in CreateWindow().
@@ -655,8 +758,11 @@
             bd->MouseTrackedArea = area;
         }
         POINT mouse_pos = { (LONG)GET_X_LPARAM(lParam), (LONG)GET_Y_LPARAM(lParam) };
-        if (msg == WM_NCMOUSEMOVE) // WM_NCMOUSEMOVE are absolute coordinates.
-             ::ScreenToClient(hwnd, &mouse_pos);
+        bool want_absolute_pos = (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) != 0;
+        if (msg == WM_MOUSEMOVE && want_absolute_pos)    // WM_MOUSEMOVE are client-relative coordinates.
+            ::ClientToScreen(hwnd, &mouse_pos);
+        if (msg == WM_NCMOUSEMOVE && !want_absolute_pos) // WM_NCMOUSEMOVE are absolute coordinates.
+            ::ScreenToClient(hwnd, &mouse_pos);
         io.AddMouseSourceEvent(mouse_source);
         io.AddMousePosEvent((float)mouse_pos.x, (float)mouse_pos.y);
         return 0;
@@ -826,6 +932,20 @@
             bd->WantUpdateHasGamepad = true;
 #endif
         return 0;
+    case WM_DISPLAYCHANGE:
+        bd->WantUpdateMonitors = true;
+        return 0;
+    case WM_SETTINGCHANGE:
+        if (wParam == SPI_SETWORKAREA)
+            bd->WantUpdateMonitors = true;
+        return 0;
+    case WM_DPICHANGED:
+    {
+        const RECT* suggested_rect = (RECT*)lParam;
+        if (io.ConfigDpiScaleViewports)
+            ::SetWindowPos(hwnd, nullptr, suggested_rect->left, suggested_rect->top, suggested_rect->right - suggested_rect->left, suggested_rect->bottom - suggested_rect->top, SWP_NOZORDER | SWP_NOACTIVATE);
+        return 0;
+    }
     }
     return 0;
 }
@@ -890,6 +1010,10 @@
 // Helper function to enable DPI awareness without setting up a manifest
 void ImGui_ImplWin32_EnableDpiAwareness()
 {
+    // Make sure monitors will be updated with latest correct scaling
+    if (ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData())
+        bd->WantUpdateMonitors = true;
+
     if (_IsWindows10OrGreater())
     {
         static HINSTANCE user32_dll = ::LoadLibraryA("user32.dll"); // Reference counted per-process
@@ -990,6 +1114,386 @@
 }
 
 //---------------------------------------------------------------------------------------------------------
+// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
+// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
+// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
+//--------------------------------------------------------------------------------------------------------
+
+// Helper structure we store in the void* PlatformUserData field of each ImGuiViewport to easily retrieve our backend data.
+struct ImGui_ImplWin32_ViewportData
+{
+    HWND    Hwnd;               // Stored in ImGuiViewport::PlatformHandle + PlatformHandleRaw
+    HWND    HwndParent;
+    bool    HwndOwned;
+    DWORD   DwStyle;
+    DWORD   DwExStyle;
+
+    ImGui_ImplWin32_ViewportData() { Hwnd = HwndParent = nullptr; HwndOwned = false;  DwStyle = DwExStyle = 0; }
+    ~ImGui_ImplWin32_ViewportData() { IM_ASSERT(Hwnd == nullptr); }
+};
+
+static void ImGui_ImplWin32_GetWin32StyleFromViewportFlags(ImGuiViewportFlags flags, DWORD* out_style, DWORD* out_ex_style)
+{
+    if (flags & ImGuiViewportFlags_NoDecoration)
+        *out_style = WS_POPUP;
+    else
+        *out_style = WS_OVERLAPPEDWINDOW;
+
+    if (flags & ImGuiViewportFlags_NoTaskBarIcon)
+        *out_ex_style = WS_EX_TOOLWINDOW;
+    else
+        *out_ex_style = WS_EX_APPWINDOW;
+
+    if (flags & ImGuiViewportFlags_TopMost)
+        *out_ex_style |= WS_EX_TOPMOST;
+}
+
+static HWND ImGui_ImplWin32_GetHwndFromViewport(ImGuiViewport* viewport)
+{
+    if (viewport != nullptr)
+        return (HWND)viewport->PlatformHandle;
+    return nullptr;
+}
+
+static void ImGui_ImplWin32_CreateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = IM_NEW(ImGui_ImplWin32_ViewportData)();
+    viewport->PlatformUserData = vd;
+
+    // Select style and parent window
+    ImGui_ImplWin32_GetWin32StyleFromViewportFlags(viewport->Flags, &vd->DwStyle, &vd->DwExStyle);
+    vd->HwndParent = ImGui_ImplWin32_GetHwndFromViewport(viewport->ParentViewport);
+
+    // Create window
+    RECT rect = { (LONG)viewport->Pos.x, (LONG)viewport->Pos.y, (LONG)(viewport->Pos.x + viewport->Size.x), (LONG)(viewport->Pos.y + viewport->Size.y) };
+    ::AdjustWindowRectEx(&rect, vd->DwStyle, FALSE, vd->DwExStyle);
+    vd->Hwnd = ::CreateWindowExW(
+        vd->DwExStyle, L"ImGui Platform", L"Untitled", vd->DwStyle,       // Style, class name, window name
+        rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top,    // Window area
+        vd->HwndParent, nullptr, ::GetModuleHandle(nullptr), nullptr);          // Owner window, Menu, Instance, Param
+    vd->HwndOwned = true;
+    viewport->PlatformRequestResize = false;
+    viewport->PlatformHandle = viewport->PlatformHandleRaw = vd->Hwnd;
+
+    // Secondary viewports store their imgui context
+    ::SetPropA(vd->Hwnd, "IMGUI_CONTEXT", ImGui::GetCurrentContext());
+}
+
+static void ImGui_ImplWin32_DestroyWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData();
+    if (ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData)
+    {
+        if (::GetCapture() == vd->Hwnd)
+        {
+            // Transfer capture so if we started dragging from a window that later disappears, we'll still receive the MOUSEUP event.
+            ::ReleaseCapture();
+            ::SetCapture(bd->hWnd);
+        }
+        if (vd->Hwnd && vd->HwndOwned)
+            ::DestroyWindow(vd->Hwnd);
+        vd->Hwnd = nullptr;
+        IM_DELETE(vd);
+    }
+    viewport->PlatformUserData = viewport->PlatformHandle = nullptr;
+}
+
+static void ImGui_ImplWin32_ShowWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+
+    // ShowParent() even with SW_SHOWNA also brings parent to front, which is not always desirable,
+    // so we temporarily disable parenting. (#7354, #8669)
+    bool avoid_bringing_parent_to_front = vd->HwndParent != NULL && (viewport->Flags & (ImGuiViewportFlags_NoFocusOnAppearing | ImGuiViewportFlags_NoTaskBarIcon)) != 0;
+    if (avoid_bringing_parent_to_front)
+        ::SetWindowLongPtr(vd->Hwnd, GWLP_HWNDPARENT, (LONG_PTR)nullptr);
+
+    if (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing)
+        ::ShowWindow(vd->Hwnd, SW_SHOWNA);
+    else
+        ::ShowWindow(vd->Hwnd, SW_SHOW);
+
+    // Restore
+    if (avoid_bringing_parent_to_front)
+        ::SetWindowLongPtr(vd->Hwnd, GWLP_HWNDPARENT, (LONG_PTR)vd->HwndParent);
+}
+
+static void ImGui_ImplWin32_UpdateWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+
+    // Update Win32 parent if it changed _after_ creation
+    // Unlike style settings derived from configuration flags, this is more likely to change for advanced apps that are manipulating ParentViewportID manually.
+    HWND new_parent = ImGui_ImplWin32_GetHwndFromViewport(viewport->ParentViewport);
+    if (new_parent != vd->HwndParent)
+    {
+        // Win32 windows can either have a "Parent" (for WS_CHILD window) or an "Owner" (which among other thing keeps window above its owner).
+        // Our Dear Imgui-side concept of parenting only mostly care about what Win32 call "Owner".
+        // The parent parameter of CreateWindowEx() sets up Parent OR Owner depending on WS_CHILD flag. In our case an Owner as we never use WS_CHILD.
+        // Calling ::SetParent() here would be incorrect: it will create a full child relation, alter coordinate system and clipping.
+        // Calling ::SetWindowLongPtr() with GWLP_HWNDPARENT seems correct although poorly documented.
+        // https://devblogs.microsoft.com/oldnewthing/20100315-00/?p=14613
+        vd->HwndParent = new_parent;
+        ::SetWindowLongPtr(vd->Hwnd, GWLP_HWNDPARENT, (LONG_PTR)vd->HwndParent);
+    }
+
+    // (Optional) Update Win32 style if it changed _after_ creation.
+    // Generally they won't change unless configuration flags are changed, but advanced uses (such as manually rewriting viewport flags) make this useful.
+    DWORD new_style;
+    DWORD new_ex_style;
+    ImGui_ImplWin32_GetWin32StyleFromViewportFlags(viewport->Flags, &new_style, &new_ex_style);
+
+    // Only reapply the flags that have been changed from our point of view (as other flags are being modified by Windows)
+    if (vd->DwStyle != new_style || vd->DwExStyle != new_ex_style)
+    {
+        // (Optional) Update TopMost state if it changed _after_ creation
+        bool top_most_changed = (vd->DwExStyle & WS_EX_TOPMOST) != (new_ex_style & WS_EX_TOPMOST);
+        HWND insert_after = top_most_changed ? ((viewport->Flags & ImGuiViewportFlags_TopMost) ? HWND_TOPMOST : HWND_NOTOPMOST) : 0;
+        UINT swp_flag = top_most_changed ? 0 : SWP_NOZORDER;
+
+        // Apply flags and position (since it is affected by flags)
+        vd->DwStyle = new_style;
+        vd->DwExStyle = new_ex_style;
+        ::SetWindowLong(vd->Hwnd, GWL_STYLE, vd->DwStyle);
+        ::SetWindowLong(vd->Hwnd, GWL_EXSTYLE, vd->DwExStyle);
+        RECT rect = { (LONG)viewport->Pos.x, (LONG)viewport->Pos.y, (LONG)(viewport->Pos.x + viewport->Size.x), (LONG)(viewport->Pos.y + viewport->Size.y) };
+        ::AdjustWindowRectEx(&rect, vd->DwStyle, FALSE, vd->DwExStyle); // Client to Screen
+        ::SetWindowPos(vd->Hwnd, insert_after, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, swp_flag | SWP_NOACTIVATE | SWP_FRAMECHANGED);
+        ::ShowWindow(vd->Hwnd, SW_SHOWNA); // This is necessary when we alter the style
+        viewport->PlatformRequestMove = viewport->PlatformRequestResize = true;
+    }
+}
+
+static ImVec2 ImGui_ImplWin32_GetWindowPos(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    POINT pos = { 0, 0 };
+    ::ClientToScreen(vd->Hwnd, &pos);
+    return ImVec2((float)pos.x, (float)pos.y);
+}
+
+static void ImGui_ImplWin32_UpdateWin32StyleFromWindow(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    vd->DwStyle = ::GetWindowLongW(vd->Hwnd, GWL_STYLE);
+    vd->DwExStyle = ::GetWindowLongW(vd->Hwnd, GWL_EXSTYLE);
+}
+
+static void ImGui_ImplWin32_SetWindowPos(ImGuiViewport* viewport, ImVec2 pos)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    RECT rect = { (LONG)pos.x, (LONG)pos.y, (LONG)pos.x, (LONG)pos.y };
+    if (viewport->Flags & ImGuiViewportFlags_OwnedByApp)
+        ImGui_ImplWin32_UpdateWin32StyleFromWindow(viewport); // Not our window, poll style before using
+    ::AdjustWindowRectEx(&rect, vd->DwStyle, FALSE, vd->DwExStyle);
+    ::SetWindowPos(vd->Hwnd, nullptr, rect.left, rect.top, 0, 0, SWP_NOZORDER | SWP_NOSIZE | SWP_NOACTIVATE);
+}
+
+static ImVec2 ImGui_ImplWin32_GetWindowSize(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    RECT rect;
+    ::GetClientRect(vd->Hwnd, &rect);
+    return ImVec2(float(rect.right - rect.left), float(rect.bottom - rect.top));
+}
+
+static void ImGui_ImplWin32_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    RECT rect = { 0, 0, (LONG)size.x, (LONG)size.y };
+    if (viewport->Flags & ImGuiViewportFlags_OwnedByApp)
+        ImGui_ImplWin32_UpdateWin32StyleFromWindow(viewport); // Not our window, poll style before using
+    ::AdjustWindowRectEx(&rect, vd->DwStyle, FALSE, vd->DwExStyle); // Client to Screen
+    ::SetWindowPos(vd->Hwnd, nullptr, 0, 0, rect.right - rect.left, rect.bottom - rect.top, SWP_NOZORDER | SWP_NOMOVE | SWP_NOACTIVATE);
+}
+
+static void ImGui_ImplWin32_SetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    ::BringWindowToTop(vd->Hwnd);
+    ::SetForegroundWindow(vd->Hwnd);
+    ::SetFocus(vd->Hwnd);
+}
+
+static bool ImGui_ImplWin32_GetWindowFocus(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    return ::GetForegroundWindow() == vd->Hwnd;
+}
+
+static bool ImGui_ImplWin32_GetWindowMinimized(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    return ::IsIconic(vd->Hwnd) != 0;
+}
+
+static void ImGui_ImplWin32_SetWindowTitle(ImGuiViewport* viewport, const char* title)
+{
+    // ::SetWindowTextA() doesn't properly handle UTF-8 so we explicitely convert our string.
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    int n = ::MultiByteToWideChar(CP_UTF8, 0, title, -1, nullptr, 0);
+    ImVector<wchar_t> title_w;
+    title_w.resize(n);
+    ::MultiByteToWideChar(CP_UTF8, 0, title, -1, title_w.Data, n);
+
+    // Calling SetWindowTextW() in a project where UNICODE is not set doesn't work but there's a trick
+    // which is to pass it directly to the DefWindowProcW() handler.
+    // See: https://stackoverflow.com/questions/9410681/setwindowtextw-in-an-ansi-project
+    //::SetWindowTextW(vd->Hwnd, title_w.Data);
+    ::DefWindowProcW(vd->Hwnd, WM_SETTEXT, 0, (LPARAM)title_w.Data);
+}
+
+static void ImGui_ImplWin32_SetWindowAlpha(ImGuiViewport* viewport, float alpha)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    IM_ASSERT(alpha >= 0.0f && alpha <= 1.0f);
+    if (alpha < 1.0f)
+    {
+        DWORD ex_style = ::GetWindowLongW(vd->Hwnd, GWL_EXSTYLE) | WS_EX_LAYERED;
+        ::SetWindowLongW(vd->Hwnd, GWL_EXSTYLE, ex_style);
+        ::SetLayeredWindowAttributes(vd->Hwnd, 0, (BYTE)(255 * alpha), LWA_ALPHA);
+    }
+    else
+    {
+        DWORD ex_style = ::GetWindowLongW(vd->Hwnd, GWL_EXSTYLE) & ~WS_EX_LAYERED;
+        ::SetWindowLongW(vd->Hwnd, GWL_EXSTYLE, ex_style);
+    }
+}
+
+static float ImGui_ImplWin32_GetWindowDpiScale(ImGuiViewport* viewport)
+{
+    ImGui_ImplWin32_ViewportData* vd = (ImGui_ImplWin32_ViewportData*)viewport->PlatformUserData;
+    IM_ASSERT(vd->Hwnd != 0);
+    return ImGui_ImplWin32_GetDpiScaleForHwnd(vd->Hwnd);
+}
+
+// FIXME-DPI: Testing DPI related ideas
+static void ImGui_ImplWin32_OnChangedViewport(ImGuiViewport* viewport)
+{
+    (void)viewport;
+#if 0
+    ImGuiStyle default_style;
+    //default_style.WindowPadding = ImVec2(0, 0);
+    //default_style.WindowBorderSize = 0.0f;
+    //default_style.ItemSpacing.y = 3.0f;
+    //default_style.FramePadding = ImVec2(0, 0);
+    default_style.ScaleAllSizes(viewport->DpiScale);
+    ImGuiStyle& style = ImGui::GetStyle();
+    style = default_style;
+#endif
+}
+
+namespace ImGui { extern ImGuiIO& GetIO(ImGuiContext*); extern ImGuiPlatformIO& GetPlatformIO(ImGuiContext*); }
+
+static LRESULT CALLBACK ImGui_ImplWin32_WndProcHandler_PlatformWindow(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
+{
+    // Allow secondary viewport WndProc to be called regardless of current context
+    ImGuiContext* ctx = (ImGuiContext*)::GetPropA(hWnd, "IMGUI_CONTEXT");
+    if (ctx == NULL)
+        return ::DefWindowProcW(hWnd, msg, wParam, lParam); // unlike ImGui_ImplWin32_WndProcHandler() we are called directly by Windows, we can't just return 0.
+
+    ImGuiIO& io = ImGui::GetIO(ctx);
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO(ctx);
+    LRESULT result = 0;
+    if (ImGui_ImplWin32_WndProcHandlerEx(hWnd, msg, wParam, lParam, io))
+        result = 1;
+    else if (ImGuiViewport* viewport = ImGui_ImplWin32_FindViewportByPlatformHandle(platform_io, hWnd))
+    {
+        switch (msg)
+        {
+        case WM_CLOSE:
+            viewport->PlatformRequestClose = true;
+            return 0; // 0 = Operating system will ignore the message and not destroy the window. We close ourselves.
+        case WM_MOVE:
+            viewport->PlatformRequestMove = true;
+            break;
+        case WM_SIZE:
+            viewport->PlatformRequestResize = true;
+            break;
+        case WM_MOUSEACTIVATE:
+            if (viewport->Flags & ImGuiViewportFlags_NoFocusOnClick)
+                result = MA_NOACTIVATE;
+            break;
+        case WM_NCHITTEST:
+            // Let mouse pass-through the window. This will allow the backend to call io.AddMouseViewportEvent() correctly. (which is optional).
+            // The ImGuiViewportFlags_NoInputs flag is set while dragging a viewport, as want to detect the window behind the one we are dragging.
+            // If you cannot easily access those viewport flags from your windowing/event code: you may manually synchronize its state e.g. in
+            // your main loop after calling UpdatePlatformWindows(). Iterate all viewports/platform windows and pass the flag to your windowing system.
+            if (viewport->Flags & ImGuiViewportFlags_NoInputs)
+                result = HTTRANSPARENT;
+            break;
+        }
+    }
+    if (result == 0)
+        result = ::DefWindowProcW(hWnd, msg, wParam, lParam);
+    return result;
+}
+
+static void ImGui_ImplWin32_InitMultiViewportSupport(bool platform_has_own_dc)
+{
+    WNDCLASSEXW wcex;
+    wcex.cbSize = sizeof(WNDCLASSEXW);
+    wcex.style = CS_HREDRAW | CS_VREDRAW | (platform_has_own_dc ? CS_OWNDC : 0);
+    wcex.lpfnWndProc = ImGui_ImplWin32_WndProcHandler_PlatformWindow;
+    wcex.cbClsExtra = 0;
+    wcex.cbWndExtra = 0;
+    wcex.hInstance = ::GetModuleHandle(nullptr);
+    wcex.hIcon = nullptr;
+    wcex.hCursor = nullptr;
+    wcex.hbrBackground = (HBRUSH)(COLOR_BACKGROUND + 1);
+    wcex.lpszMenuName = nullptr;
+    wcex.lpszClassName = L"ImGui Platform";
+    wcex.hIconSm = nullptr;
+    ::RegisterClassExW(&wcex);
+
+    ImGui_ImplWin32_UpdateMonitors();
+
+    // Register platform interface (will be coupled with a renderer interface)
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    platform_io.Platform_CreateWindow = ImGui_ImplWin32_CreateWindow;
+    platform_io.Platform_DestroyWindow = ImGui_ImplWin32_DestroyWindow;
+    platform_io.Platform_ShowWindow = ImGui_ImplWin32_ShowWindow;
+    platform_io.Platform_SetWindowPos = ImGui_ImplWin32_SetWindowPos;
+    platform_io.Platform_GetWindowPos = ImGui_ImplWin32_GetWindowPos;
+    platform_io.Platform_SetWindowSize = ImGui_ImplWin32_SetWindowSize;
+    platform_io.Platform_GetWindowSize = ImGui_ImplWin32_GetWindowSize;
+    platform_io.Platform_SetWindowFocus = ImGui_ImplWin32_SetWindowFocus;
+    platform_io.Platform_GetWindowFocus = ImGui_ImplWin32_GetWindowFocus;
+    platform_io.Platform_GetWindowMinimized = ImGui_ImplWin32_GetWindowMinimized;
+    platform_io.Platform_SetWindowTitle = ImGui_ImplWin32_SetWindowTitle;
+    platform_io.Platform_SetWindowAlpha = ImGui_ImplWin32_SetWindowAlpha;
+    platform_io.Platform_UpdateWindow = ImGui_ImplWin32_UpdateWindow;
+    platform_io.Platform_GetWindowDpiScale = ImGui_ImplWin32_GetWindowDpiScale; // FIXME-DPI
+    platform_io.Platform_OnChangedViewport = ImGui_ImplWin32_OnChangedViewport; // FIXME-DPI
+
+    // Register main window handle (which is owned by the main application, not by us)
+    // This is mostly for simplicity and consistency, so that our code (e.g. mouse handling etc.) can use same logic for main and secondary viewports.
+    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData();
+    ImGui_ImplWin32_ViewportData* vd = IM_NEW(ImGui_ImplWin32_ViewportData)();
+    vd->Hwnd = bd->hWnd;
+    vd->HwndOwned = false;
+    main_viewport->PlatformUserData = vd;
+}
+
+static void ImGui_ImplWin32_ShutdownMultiViewportSupport()
+{
+    ::UnregisterClassW(L"ImGui Platform", ::GetModuleHandle(nullptr));
+    ImGui::DestroyPlatformWindows();
+}
+
+//---------------------------------------------------------------------------------------------------------
 
 #if defined(__GNUC__)
 #pragma GCC diagnostic pop

diff --git a/backends/imgui_impl_win32.h b/backends/imgui_impl_win32.h
index d2a9600..0f1b9b2 100644
--- a/backends/imgui_impl_win32.h
+++ b/backends/imgui_impl_win32.h

@@ -7,6 +7,7 @@
 //  [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy VK_* values are obsolete since 1.87 and not supported since 1.91.5]
 //  [X] Platform: Gamepad support.
 //  [X] Platform: Mouse cursor shape and visibility (ImGuiBackendFlags_HasMouseCursors). Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
+//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
 
 // You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
 // Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.

diff --git a/docs/BACKENDS.md b/docs/BACKENDS.md
index 7839764..091de1b 100644
--- a/docs/BACKENDS.md
+++ b/docs/BACKENDS.md

@@ -183,6 +183,7 @@
   - `ImGuiBackendFlags_HasSetMousePos`: supports io.WantSetMousePos requests to reposition the OS mouse position (only used if io.ConfigNavMoveSetMousePos is set).
   - `ImGuiBackendFlags_PlatformHasViewports` supports multiple viewports. (multi-viewports only)
   - `ImGuiBackendFlags_HasMouseHoveredViewport` supports calling io.AddMouseViewportEvent() with the viewport under the mouse. IF POSSIBLE, ignore viewports with the ImGuiViewportFlags_NoInputs flag. If this cannot be done, Dear ImGui needs to use a flawed heuristic to find the viewport under mouse position, as it doesn't know about foreign windows. (multi-viewports only)
+  - `ImGuiBackendFlags_HasParentViewport` supports honoring viewport->ParentViewportId value, by applying the corresponding parent/child relation at the Platform level.
 
 **In your `ImGui_ImplXXX_NewFrame()` function:**
 - Set `io.DeltaTime` to the time elapsed (in seconds) since last frame.

diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index f63c073..5bbb533 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt

@@ -276,6 +276,37 @@
    - Win32+DirectX12: ignore seemingly incorrect `D3D12_MESSAGE_ID_FENCE_ZERO_WAIT`
      warning on startups on some setups. (#9084, #9093) [@RT2Code, @LeoGautheron]
 
+Docking+Viewports Branch:
+
+- Docking:
+  - Fixed various rendering issues and ability to have rounded floating dock nodes.
+    (#6993, #6151) - please note that rounding is still disabled on standalone
+    viewports.
+  - Fixed implicit/fallback "Debug" window from staying visible if once docked. (#9151)
+  - Demo: rework 'Dockspace' demo to increase clarity and put more emphasis on the
+    basic path of simply calling `DockSpaceOverViewport()`.
+- Viewports:
+  - Fixed a regression in 1.92.4 where partially moving a floating docking node
+    with horizontal/vertical split over the main viewport would set the window in
+    an invalid state in some situations, making user unable to further interact
+    with the window.
+  - Fixed a regression in 1.92.4 which could cause combos/popups window from
+    appearing under their parent viewport if their geometry overlapped the main
+    viewport. (#8948, #9172, #9131, #9128)
+  - Fixed an assert in background dimming code, which could trigger after using
+    gamepad/keyboard to move a window to another viewport. (#9053) [@lut0pia, @ocornut]
+- Backends:
+  - GLFW: dynamically load X11 functions to avoid `-lx11` linking requirement introduced
+    in 1.92.3. (#9116, #9109) [@ramenguy99]
+  - GLFW: improve workarounds for cases where GLFW is unable to provide reliable monitor 
+    info. Preserve existing monitor list when none of the new one is valid. (#9195, #7902, #5683)
+  - SDL2, SDL3: adjust IME offset to match other backends and master branch. (#6071, #1953)
+  - Win32: viewports created by backend forcefully direct messages to
+    `DefWindowProcW()` in order to support Unicode text input. (#9099, #3653, #5961) [@ulhc]
+  - Win32: fixed an issue from 1.90.5 where newly appearing windows that are not parented
+    to the main viewport didn't have their task bar icon appear before the window was
+    explicitly refocused. (#7354, #8669)
+
 
 -----------------------------------------------------------------------
  VERSION 1.92.5 (Released 2025-11-20)
@@ -421,6 +452,22 @@
   - SDL3+WebGPU: added new example (Emscripten + native Dawn/WGPU). (#8381) [@brutpitt]
   - Win32+OpenGL3: enable DPI awareness. (#9083)
 
+Docking+Viewports Branch:
+
+- Docking, Style: fixed per-window ImGuiCol_UnsavedMarker changes not being latched
+  by docked windows. (#8983, #9064)
+- Docking: fixed crash loading certain form of invalid .ini settings (e.g. nodes 
+  referring to a missing parent, duplicate nodes id). (#9070)
+- Docking: added io.ConfigDockingNoDockingOver helper config flag to prevent
+  merging windows into a same tab-bar.
+- Examples:
+  - SDL2+DX11, SDL3+DX11, Win32+DX10, Win32+DX11: fixed one resource leak
+    from the use of MakeWindowAssociation() in 1.92.4. (#9010, #4350) [@o-3-o]
+- Backends:
+  - DirectX12: Fixed an issue in synchronization logic improving rendering
+    throughput for secondary viewports. (#9025, #8961)
+  - Vulkan: handle viewport surface creation failure without crashing. (#9068) [@zentia]
+
 
 -----------------------------------------------------------------------
  VERSION 1.92.4 (Released 2025-10-14)
@@ -430,6 +477,10 @@
 
 Breaking Changes:
 
+- Viewports: for consistency with other config flags, renamed
+     io.ConfigViewportPlatformFocusSetsImGuiFocus
+  to io.ConfigViewportsPlatformFocusSetsImGuiFocus. (#6299, #6462)
+  It was really a typo in the first place, and introduced in 1.92.2.
 - Backends:
   - TreeNode, Selectable, Clipper: commented out legacy names obsoleted in
     1.89.7 (July 2023) and 1.89.9 (Sept 2023):
@@ -531,6 +582,50 @@
   - Win32+DirectX12: Rework synchronization logic. (#8961) [@RT2Code]
   - Made examples's main.cpp consistent with returning 1 on error.
 
+Docking+Viewports Branch:
+
+- Nav, Docking, Selection: Fixed tab change from reinitializing navigation state,
+  which would erroneously clear selection when using ImGuiSelectableFlags_SelectOnNav
+  or clear multi-selection when not using ImGuiMultiSelectFlags_NoAutoSelect. (#8997)
+- Nav: Fixed a crash that could occur when opening a popup following the processing
+  of a global shortcut while no windows were focused (the fix done in 1.92.3 was
+  incomplete for docking branch).
+- Viewports:
+  - Added ImGuiBackendFlags_HasParentViewport backend flag for
+    backend to specify if it can honor the `viewport->ParentViewport`/`ParentViewportId`
+    value by applying the corresponding parent/child relation at the Platform level. (#8948)
+    - SDL3, Win32 backends: supported.
+    - SDL2, GLFW, OSX backends: unsupported.
+  - Fixed a bug where ImGuiWindowFlags_NoBringToFrontOnFocus would effectively
+    be ignored when windows first appear and viewports are enabled. (#7008) [@jshofmann]
+  - Changed default value of io.ConfigViewportsNoDefaultParent to true. (#8948)
+  - Fixed an issue inferring Z-order when attempting to merge a viewport
+    back in the the main/hosting viewport. (#8948)
+    Note that for GLFW/SDL2/OSX backends, which do not support honoring ParentViewportID.
+    Setting io.ConfigViewportsNoDefaultParent=true will align imgui's expectation
+    with what the backend does.
+  - Storing `ImGuiViewport* ParentViewport` pointer along with ParentViewportID.
+  - ImGui::DestroyContext() does not call DestroyPlatformWindows() anymore at it
+    is assumed to be unnecessary as backends should have done it and we check that
+    backends have been shutdown since 1.90.4. Changed into asserts. (#7175, #8945)
+- Backends:
+  - DirectX10, DirectX11, DirectX12: Disabled DXGI's Alt+Enter default behavior on
+    secondary viewports managed by the backend. (#4350) [@PathogenDavid]
+  - DirectX10, DirectX11: avoid ImGui_ImplXXXX_SwapBuffers() handlers for secondary
+    viewports crashing if SwapChain could not be created.
+  - Vulkan: Added a way to configure secondary viewport pipeline creation by
+    setting init_info.PipelineInfoForViewports fields. (#8946, #8110, #8111, #8686)
+  - Vulkan: Added a way to configure secondary viewport swapchain VkImageUsageFlags
+    to e.g. capture rendering. (#8946, #8940) [@olivier-gerard, @ocornut]
+    Usage example: `init_info.PipelineInfoForViewports.SwapChainImageUsage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_TRANSFER_SRC_BIT;`
+  - Vulkan: pipeline created for secondary viewport automatically match
+    surface format. (#8686) [@sylmroz]
+  - Vulkan: Added ImGui_ImplVulkanH_GetWindowDataFromViewport() accessor/helper. (#8946, #8940) [@olivier-gerard]
+- Docs: improve docking API comments and demo. (#9000)
+- Examples: DX10, DX11: Disabled DXGI's Alt+Enter default behavior in examples.
+  Applications are free to leave this enabled, but it does not work properly with
+  multiple viewports. (#4350, #8979) [@PathogenDavid]
+
 
 -----------------------------------------------------------------------
  VERSION 1.92.3 (Released 2025-09-17)
@@ -625,6 +720,22 @@
 - Backends: Vulkan: added ImGui_ImplVulkan_CreateMainPipeline() to recreate pipeline
   without reinitializing backend. (#8110, #8111) [@SuperRonan]
 
+Docking+Viewports Branch:
+
+- DPI: fixed io.ConfigDpiScaleFonts from ever working since 1.92 (the irony
+  being that it is when it started to make sense!). As a reminder, the option
+  automatically copy the _current_ viewport DpiScale to style.FontScaleDpi.
+  This is why we separated the style.FontScaleMain and style.FontScaleDpi scaling
+  factor, as the later is meant to be overwritten. (#8832, #8465)
+- DPI: Fixed obsoleted ImGuiConfigFlags_DpiEnableScaleFonts/_DpiEnableScaleViewports
+  names from setting the equivalent io.ConfigDpiScaleFonts/io.ConfigDpiScaleViewports
+  flag correctly (regression in 1.92).
+- Docking, Style: added style.DockingNodeHasCloseButton option to hide the
+  Close Button attached to each docking node. (#8933)
+- Backends: GLFW: improve multi-viewport behavior in tiling WMs on X11.
+  Note: using GLFW backend on Linux/BSD etc. requires linking with `-lX11`.
+  (#8884, #8474, #8289, #2117) [@Ikos3k, @Madman10K]
+
 
 -----------------------------------------------------------------------
  VERSION 1.92.2b (Released 2025-08-13)
@@ -646,6 +757,12 @@
 - Backends: Allegro5: Fixed missing support for ImGuiKey_PrintScreen
   under Windows, as raw Allegro 5 does not receive it.
 
+Docking+Viewports Branch:
+
+- Fixed a bug where closing a viewport using OS facility (e.g. ALT+F4, Close Button)
+  would erroneously close all windows located in the viewport, even ones docked
+  into nested dockspaces. Only top-most windows should be closed. (#8887) [@lailoken]
+
 
 -----------------------------------------------------------------------
  VERSION 1.92.2 (Released 2025-08-11)
@@ -733,6 +850,19 @@
 - Backends: Vulkan: Avoid calling vkCmdBindDescriptorSets() when texture
   has not changed. (#8666) [@micb25]
 
+Docking+Viewports Branch:
+
+- Windows, Viewport: fixed an issue where interrupting a viewport move with
+  e.g. a ClearActiveID() call would leave the dragged viewport with the
+  normally temporary ImGuiViewportFlags_NoInputs flag, preventing further
+  interactions with the viewport. (#5324) (thanks @mdelaharpe)
+- Viewports: added io.ConfigViewportPlatformFocusSetsImGuiFocus to opt-out
+  of focusing imgui windows When a platform window is focused (e.g. using Alt+Tab,
+  clicking Platform Title Bar). In principle this is better enabled but we
+  provide an opt-out because some Linux window managers tend to eagerly focus
+  windows (on e.g. mouse hover, or even on a simple window pos/size change).
+  (#6299, #6462)
+
 
 -----------------------------------------------------------------------
  VERSION 1.92.1 (Released 2025-07-09)
@@ -782,6 +912,10 @@
 - Backends: Vulkan: fixed texture synchronization issue introduced in 1.92.0,
   leading to validation layers reacting. (#8772) [@Majora320]
 
+Docking+Viewports Branch:
+
+- Backends: OSX: Fixed multi-viewport handling broken in 1.92.0. (#8644, #8777) [@cfillion]
+
 
 -----------------------------------------------------------------------
  VERSION 1.92.0 (Released 2025-06-25)
@@ -1009,6 +1143,9 @@
    - Imgui_ImplSDLGPU3_PrepareDrawData() --> ImGui_ImplSDLGPU3_PrepareDrawData()
 - Internals: RenderTextEllipsis() function removed the 'float clip_max_x' parameter directly
   preceding 'float ellipsis_max_x'. Values were identical for a vast majority of users. (#8387)
+- [Docking] renamed/moved ImGuiConfigFlags_DpiEnableScaleFonts     -> bool io.ConfigDpiScaleFonts.
+- [Docking] renamed/moved ImGuiConfigFlags_DpiEnableScaleViewports -> bool io.ConfigDpiScaleViewports.
+  **Neither of those flags are very useful in current code. They will be useful once we merge font changes.**
 
 Non-breaking Fonts/Textures related changes:
 
@@ -1242,6 +1379,35 @@
   - Examples: DirectX12+Win32: also test for IsIconic() for sleeping since we don't seem to
     get a DXGI_STATUS_OCCLUDED signal when minimized. (#8603) [@dooann]
 
+Docking+Viewports Branch:
+
+- Viewports: added per-viewport FramebufferScale for Retina display multi-monitor support.
+  Backend must provide platform_io.platform_io.Platform_GetWindowFramebufferScale handler.
+  This effectively fixes clipping/rendering on multi-monitors with varying Retina scale.
+  (#1065, #1542, #1676, #1786, #2826, #3757, #5081, #5580, #5592, #6465, #7273, #7779 etc.)
+- Viewports: fixed handling of simultaneous move + resize (e.g. toggling maximized)
+  when ImGuiConfigFlags_DpiEnableScaleViewports is enabled.
+- Backends: Win32: Viewports: fixed an issue when closing a window from
+  the OS close button (with io.ConfigViewportsNoDecoration=false) while
+  user code is discarding the 'bool *p_open=false output' from Begin().
+  Because we allowed the Win32 window to close early, Windows destroyed
+  it and our imgui window became not visible even though user code was
+  still submitting it. (#8670)
+- Backends: Win32: Viewports: handle WM_DPICHANGED in backend when
+  ImGuiConfigFlags_DpiEnableScaleViewports is enabled.
+- Backends: GLFW, SDL2, SDL3, Apple: provide Platform_GetWindowFramebufferScale handler,
+  (#1065, #1542, #1676, #1786, #2826, #3757, #5081, #5580, #5592, #6465, #7273, #7779 etc.)
+- Backends: SDLGPU3 for SDL3: added multi-viewport support. (#8573) [@Lekoopapaul]
+- Backends: SDL2, SDL3: revert updating monitors and work areas info every
+  frame. Only do it on Windows to detect task-bar resize until we get an
+  adequate event for it. (#8415, #8558)
+- Backends: SDL3: macOS: Fixed secondary-viewports not appearing on a different
+  monitor than the main viewport. Because SDL_SetWindowParent() seems to restrict it.
+- Backends: GLFW: Disable multi-viewports under Wayland (require GLFW 3.4). (#8587)
+- Backends: GLFW: Fixed an issue where Win32 specific WndProc hook was not installed
+  for all GLFW version, preventing mouse vs touch detection from working on
+  secondary viewports.
+
 
 -----------------------------------------------------------------------
  VERSION 1.91.9b (Released 2025-03-17)
@@ -1374,6 +1540,8 @@
   with asserts enabled. (#8452)
 - Backends: SDL2, SDL3: Using SDL_OpenURL() in platform_io.Platform_OpenInShellFn
   handler. (#7660) [@achabense]
+- Backends: SDL2, SDL3: Use display bounds when SDL_GetDisplayUsableBounds()
+  fails or return a zero size. (#8415, #3457)
 - Backends: SDL2, SDL3, Win32, Allegro5: Added support for ImGuiMouseCursor_Wait
   and ImGuiMouseCursor_Progress cursors.
 - Backends: SDL2, SDL3: Avoid calling SDL_GetGlobalMouseState() when mouse is in
@@ -1396,6 +1564,22 @@
   [@PhantomCloak] (#8369)
 - Backends: WebGPU: Fix for webgpu-native API changes. (#8426) [@pplux]
 
+Docking+Viewports Branch:
+
+- Docking: Removed legacy assert preventing to call DockBuilderSplitNode() on an existing
+  split node. This makes using DockBuilder a little more flexible and bearable! (#8472) [@MegaMech]
+- Viewports: fixed an issue where in certain cases, a window repositioning leading
+  to a monitor change could have the window incorrectly get clamped within the boundaries
+  of its previous monitor. Would happen e.g. when loading .ini data during runtime. (#8484)
+- Viewports: fixed an assert when a window load settings with a position outside
+  monitor bounds, when there are multiple monitors. (#8393, #8385) [@gaborodriguez]
+- Viewports + Backends: Win32: Fixed setting title bar text when application
+  is compiled without UNICODE. (#7979, #5725) [@lailoken]
+- Backends: GLFW, SDL2/SDL3: Update monitors and work areas information every frame,
+  as the later may change regardless of monitor/display changes. (#8415)
+- Backends: Win32: WM_SETTINGCHANGE's SPI_SETWORKAREA message also triggers a refresh
+  of monitor list, as they contain work area information. (#8415) [@PathogenDavid, @lailoken]
+
 
 -----------------------------------------------------------------------
  VERSION 1.91.8 (Released 2025-01-31)
@@ -1458,7 +1642,7 @@
   one without the other is never correct. (#8174, #6556, #6336, #4723)
 - Examples: DirectX12: Reduced number of frame in flight from 3 to 2 in
   provided example, to reduce latency.
-- Examples: Vulkan: better handle VK_SUBOPTIMAL_KHR being returned by
+- Backends+Examples: Vulkan: better handle VK_SUBOPTIMAL_KHR being returned by
   vkAcquireNextImageKHR() or vkQueuePresentKHR(). (#7825, #7831) [@NostraMagister]
 - Backends: SDL2: removed assert preventing using ImGui_ImplSDL2_SetGamepadMode()
   with ImGui_ImplSDL2_GamepadMode_Manual and an empty array. (#8329)
@@ -1472,6 +1656,14 @@
   ImGui_ImplDX12_InitInfo instead of creating its own.
 - Backends: OSX: Removed notification observer when shutting down. (#8331) [@jrachele]
 
+Docking+Viewports Branch:
+
+- Docking: Fixed an issue in 1.91.7 where using legacy ImGuiWindowFlags_NavFlattened
+  flag (instead of ImGuiChildFlags_NavFlattened) in docking branch would conflict
+  with internal docking flags. (#8357) [@DanielGibson]
+- Backends: SDL3: new viewport windows are created with the SDL_WINDOW_HIDDEN flag
+  before calling SDL_ShowWindow(). (#8328) [@PathogenDavid]
+
 
 -----------------------------------------------------------------------
  VERSION 1.91.7 (Released 2025-01-14)
@@ -1606,6 +1798,15 @@
 - Examples: Win32+DX12: Using a basic free-list allocator to manage multiple
   SRV descriptors.
 
+Docking+Viewports Branch:
+
+- Docking: Added an assert to clarify that ImGuiDockNodeFlags_CentralNode flag
+  (from internals) does not need to be passed to DockSpace(), as it causes general
+  havoc. (#8145)
+- Backends: Win32: Fixed a crash/regression in 1.91.5 when running two processes
+  with multi-viewports (was using GetProp() to query property which could have
+  belonged to another process). (#8162, #8069) [@sammyfreg, @ocornut]
+
 
 -----------------------------------------------------------------------
  VERSION 1.91.5 (Released 2024-11-07)
@@ -1665,6 +1866,15 @@
 - Examples: Android+OpenGL: Using ALooper_pollOnce() instead of ALooper_pollAll()
   which has been deprecated. (#8013) [@feather179]
 
+Docking+Viewports Branch:
+
+- Backends: GLFW: added Linux workaround for spurious mouse up events emitted while dragging
+  and creating new viewports. Generally they would be interrupting a dragging operations.
+  (#3158, #7733, #7922) [@rokups, @ocornut]
+- Docking: fixed using ImGuiDockNodeFlags_KeepAliveOnly with DockSpaceOverViewport():
+  the normally invisible space did erroneously claim mouse hover and could be potentially
+  focused. (#8125) [@kcbanner]
+
 
 -----------------------------------------------------------------------
  VERSION 1.91.4 (Released 2024-10-18)
@@ -1754,6 +1964,11 @@
 - Backends: DX9, DX10, DX11, DX12, OpenGL, Vulkan, WGPU: Changed default texture sampler
   to Clamp instead of Repeat/Wrap. (#7468, #7511, #5999, #5502, #7230)
 
+Docking+Viewports Branch:
+
+- Backends: changed all backends to allow enabling ImGuiConfigFlags_ViewportsEnable
+  after initialization. (#5371)
+
 
 -----------------------------------------------------------------------
  VERSION 1.91.3 (Released 2024-10-04)
@@ -1817,6 +2032,13 @@
 - Backends: WebGPU: Fixed DAWN api change using WGPUStringView in WGPUShaderSourceWGSL.
   (#8009, #8010) [@blitz-research]
 
+Docking+Viewports Branch:
+
+- Backends: SDL2, SDL3: Fixed building for UWP platforms. (#8008)
+- Backends: Win32: Use ResisterClassW()/CreateWindowExW() for secondary viewports, to
+  ensure correct IME input even if the backend was compiled in MBCS mode. (#7979, #5725)
+
+
 -----------------------------------------------------------------------
  VERSION 1.91.2 (Released 2024-09-19)
 -----------------------------------------------------------------------
@@ -1877,6 +2099,18 @@
 - Backends: WebGPU: Added support for optional IMGUI_IMPL_WEBGPU_BACKEND_DAWN / IMGUI_IMPL_WEBGPU_BACKEND_WGPU
   defines to handle ever-changing native implementations. (#7977, #7969, #6602, #6188, #7523) [@acgaudette]
 
+Docking+Viewports Branch:
+
+- Viewports: fixed an issue where a window manually constrained to the main viewport while crossing
+  over main viewport bounds isn't translated properly. (#7985)
+- Backends: SDL2, SDL3, Win32: ensure that ImGuiPlatformMonitor list is available after backend Init call. (#7995)
+- Backends: Win32: fixed direct calls to platform_io.Platform_SetWindowPos()/Platform_SetWindowSize()
+  on windows created by application (typically main viewport).
+- Backends: Win32: fixed an issue where a viewport destroyed while clicking would hog
+  mouse tracking and temporary lead to incorrect update of HoveredWindow. (#7971)
+- Backends: SDL3: added support for viewport->ParentViewportId field to support parenting
+  windows at OS level. (#7973, #7989) [@RT2code]
+
 -----------------------------------------------------------------------
  VERSION 1.91.1 (Released 2024-09-04)
 -----------------------------------------------------------------------
@@ -1960,6 +2194,16 @@
     to handle minimization without burning CPU or GPU by running unthrottled code. (#7844)
   - Examples: SDL3: Update for API changes: SDL_Init() returns 0 on failure.
 
+Docking+Viewports Branch:
+
+- Viewports: added optional platform_io.Platform_GetWindowWorkAreaInsets() hook
+  to allow backends to alter the default per-viewport work-area. (#7823)
+- Backends: don't report monitors with DpiScale of 0, which seemed to be reported for
+  virtual monitors instead by accessibility drivers. (#7902) [@nicolasnoble, @ocornut]
+- Backends: SDL2, SDL3: using SDL_HINT_WINDOW_NO_ACTIVATION_WHEN_SHOWN to support the
+  ImGuiViewportFlags_NoFocusOnAppearing flag, instead of using a Win32-specific hack.
+  (#7896) [@RT2Code]
+
 -----------------------------------------------------------------------
  VERSION 1.91.0 (Released 2024-07-30)
 -----------------------------------------------------------------------
@@ -2119,6 +2363,16 @@
   - Backends: GLFW+Emscripten: Fixed Emscripten warning when using mouse wheel on some setups
     "Unable to preventDefault inside passive event listener". (#7647, #7600) [@ypujante]
 
+Docking+Viewports Branch:
+
+- Viewports: Always update fallback monitor to primary monitor if there's one.
+- Backends: OSX: Fixed NSAppKitVersion version limit for setWantsBestResolutionOpenGLSurface
+  usage. (#7814) [@YGXXD]
+- Backends: SDL3: Fixed a bug preventing ImGuiViewportFlags_NoFocusOnAppearing support from
+  working (Windows only).
+- Backends: Vulkan: ImGui_ImplVulkan_SwapBuffers() used by secondary viewports still proceeds
+  increasing frame counters on VK_SUBOPTIMAL_KHR. (#7825, #3881) [@NostraMagister]
+
 
 -----------------------------------------------------------------------
  VERSION 1.90.9 (Released 2024-07-01)
@@ -2200,6 +2454,19 @@
   returning VK_SUBOPTIMAL_KHR, which doesn't seem to happen on Wayland. (#7671)
   [@AndreiNego, @ocornut]
 
+Docking+Viewports Branch:
+
+- Windows, Menus: Fixed an issue where the size of sub-menu in their own viewport
+  would be erroneously clamped to the size of main viewport. (#7730)
+- Merged GetBackgroundDrawList() and GetBackgroundDrawList(ImGuiViewport* viewport)
+  api entry points into a same one GetBackgroundDrawList(ImGuiViewport* viewport = NULL);
+- Merged GetForegroundDrawList() and GetForegroundDrawList(ImGuiViewport* viewport)
+  api entry points into a same one GetForegroundDrawList(ImGuiViewport* viewport = NULL);
+- Backends: SDL3: Update for introduction of SDL_GLContext from void*. (#7701, #7702)
+  [@bcsanches]
+- Backends: Win32: Secondary viewports WndProc handler retrieve/set imgui context from
+  the HWND, allowing WndProc dispatch to work in multi-context setups.
+
 
 -----------------------------------------------------------------------
  VERSION 1.90.8 (Released 2024-06-06)
@@ -2350,6 +2617,15 @@
   those API public. Only past users of imgui_internal.h with the extra parameters will be affected.
   Added asserts for valid flags in various functions to detect _some_ misuses, BUT NOT ALL.
 
+Docking+Viewports Branch:
+
+- Docking: *BREAKING* changed signature of DockSpaceOverViewport() to allow passing
+  an explicit dockspace id if desired. (#7611)
+    Before: DockSpaceOverViewport(const ImGuiViewport* viewport = NULL, ImGuiDockNodeFlags flags = 0, ...);
+    After:  DockSpaceOverViewport(ImGuiID dockspace_id = 0, const ImGuiViewport* viewport = NULL, ImGuiDockNodeFlags flags = 0, ...);
+  Simply add a leading 0 to your existing calls to DockSpaceOverViewport() if you have any.
+- Tables: resizing border hit-rect scales according to current monitor dpi scale.
+
 
 -----------------------------------------------------------------------
  VERSION 1.90.6 (Released 2024-05-08)
@@ -2408,6 +2684,18 @@
 - Examples: GLFW+WebGPU: Added support for WebGPU-native/Dawn (#7435, #7132) [@eliasdaler, @Zelif]
 - Examples: GLFW+WebGPU: Renamed example_emscripten_wgpu/ to example_glfw_wgpu/. (#7435, #7132)
 
+Docking+Viewports Branch:
+
+- Docking: when io.ConfigDockingWithShift is enabled, fixed help tooltip erroneously
+  reading SetNextWindowXXX() data. (#6709, #4643, #7491) [@ocornut, @cfillion]
+- Viewports: fixed outer-right edge of MenuBar clipping rectangle off by one when window
+  is located on a monitor with negative coordinates. (#6861, #2884) [@cfillion]
+- Backends: Vulkan: reworked swap-chain resize handling for secondary viewports, fix for
+  typical Linux setups. (#2626, #3390, #3758, #7508, #7513) [@RoryO, @InsideBSITheSecond]
+- Backends: Vulkan: create a custom pipeline for secondary viewports. Fixes issues
+  when user created main viewport uses a different renderpass. (#6325, #6305, #7398,
+  #3459, #3253, #3522) [@skaman, @FunMiles]
+
 
 -----------------------------------------------------------------------
  VERSION 1.90.5 (Released 2024-04-11)
@@ -2464,6 +2752,11 @@
     Adding a link to the crawlable version, even though it is not intended for humans,
     to increase its search rank.
 
+Docking+Viewports Branch:
+
+- Backends: Win32: made it so that an appearing viewport showing up doesn't bring
+  its parent to front. (#7354)
+
 
 -----------------------------------------------------------------------
  VERSION 1.90.4 (Released 2024-02-22)
@@ -2497,6 +2790,13 @@
 - Demo: Custom Rendering: better demonstrate PathArcTo(), PathBezierQuadraticCurveTo(),
   PathBezierCubicCurveTo(), PathStroke(), PathFillConvex() functions.
 
+Docking+Viewports Branch:
+
+- Backends: GLFW: enable ImGuiBackendFlags_HasMouseHoveredViewport support with GLFW 3.3.x,
+  as required specs for it was relaxed in 1.87. This enable better viewport hovering detection
+  without GLFW 3.4's GLFW_MOUSE_PASSTHROUGH, with less reliance on dear imgui's own heuristic
+  of platform windows order. (#7316)
+
 
 -----------------------------------------------------------------------
  VERSION 1.90.3 (Released 2024-02-14)
@@ -2585,6 +2885,18 @@
   Often requested in some form (#6962, #5219, #3290, #4627, #5054, #3878, #2881, #1506, #1216, #968),
   and useful for interactive completion/suggestions popups (#2057, #718)
 
+Docking+Viewports Branch:
+
+- Added ImGuiWindowClass::FocusRouteParentWindowId as a way to connect the focus route between
+  a tool window to a parent document window, so that Shortcuts in the documents are routed when the
+  tool is focused (regardless of whether the tool is docked or in a floating viewport, etc.) (#6798)
+- Added ImGuiDockNodeFlags_DockedWindowsInFocusRoute to automatically make a dockspace connect
+  the focus route of its docked window. This is provided a convenience in case you have windows
+  where a connection is not explicit. (#6798)
+- Viewports: Fixed moving accross monitors when io.ConfigWindowsMoveFromTitleBarOnly is set. (#7299, #3071)
+- Backends: OSX: Fixed not submitting Monitors info when viewports are not enabled, leading to
+  missing e.g. DpiScale info. (#7257) [@actboy168]
+
 
 -----------------------------------------------------------------------
  VERSION 1.90.1 (Released 2024-01-10)
@@ -2689,6 +3001,15 @@
     (#6751) [@Traveller23, @ypujante]
   - Examples: SDL3: Minor fixes following recent SDL3 in-progress development.
 
+Docking+Viewports Branch:
+
+- Windows: Fixed ImGuiCol_TitleBg/Active alpha being used for viewport-owned windows. (#7181) [@PathogenDavid]
+- Backends: DX12: Changed swapchain scaling mode to DXGI_SCALING_NONE to reduce artifacts as
+  queued frames aren't synchronized with platform window resizes. (#7152, #7153) [@SuperWangKai]
+- Backends: OSX: Fixed monitor and window position by correctly transforming Y origin on multi-viewports
+  multi-monitor setups. (#7028, #7101, #6009, #6432) [@dmirty-kuzmenko, @734vin]
+- Backends: OSX: Fixed IME position in multi-monitor multi-viewports setups. (#7028) [@734vin]
+
 
 -----------------------------------------------------------------------
  VERSION 1.90.0 (Released 2023-11-15)
@@ -2883,6 +3204,8 @@
   Fixed leaks, and added ImGui_ImplVulkan_DestroyFontsTexture() (probably no need to call this directly).
   (#6943, #6715, #6327, #3743, #4618)
   [@helynranta, @thomasherzog, @guybrush77, @albin-johansson, @MiroKaku, @benbatya-fb, @ocornut]
+- Backends: Vulkan: use specified ColorAttachmentFormat when creating a secondary window when enabling
+  UseDynamicRendering option. (#6999, #5446, #5037) [@raaaviol]
 - Backends: GLFW: Clear emscripten's MouseWheel callback before shutdown. (#6790, #6096, #4019) [@halx99]
 - Backends: GLFW: Added support for F13 to F24 function keys. (#6891)
 - Backends: SDL2, SDL3: Added support for F13 to F24 function keys, AppBack, AppForward. (#6891)
@@ -2900,6 +3223,31 @@
 - Examples: GLFW+Vulkan, SDL+Vulkan: Simplified and removed code due to backend improvements.
 - Internals: Renamed ImFloor() to ImTrunc(). Renamed ImFloorSigned() to ImFloor(). (#6861)
 
+Docking+Viewports Branch:
+
+- Viewports: Fixed window inner clipping rectangle off by one when window is located on a monitor
+  with negative coordinates. While it is expected that other small issues with arise from this
+  situation, at the moment we are fixing the most noticeable one. (#6861, #2884) [@Vuhdo, @alektron]
+- Docking: revised undocking to reduce accidental whole-node undocking:
+  - cannot undock a whole node by dragging from empty space in tab-bar.
+  - can undock whole node by dragging from window/collapse menu button.
+  - can undock single window by dragging from its tab.
+  - can still move (but not undock) whole node or whole hierarchy when node is part of a
+    floating hierarchy.
+  - added tooltip when hovering the collapse/window menu button, to faciliate understanding
+    that whole dock node may be undocked or grabbed from here.
+- Docking: Fixed an issue leading to incorrect restoration of selected tab in dock nodes that
+  don't carry the currently focused window. (#2304)
+- Docking: added ImGuiDockNodeFlags_NoUndocking. (#2999, #6823, #6780, #3492)
+- Docking: renamed ImGuiDockNodeFlags_NoSplit to ImGuiDockNodeFlags_NoDockingSplit.
+- Docking: renamed ImGuiDockNodeFlags_NoDockingInCentralNode to ImGuiDockNodeFlags_NoDockingOverCentralNode.
+- Docking: Internals: renamed ImGuiDockNodeFlags_NoDockingSplitMe to ImGuiDockNodeFlags_NoDockingSplit.
+- Docking: Fixed a bug where ClassId compare tests (when using SetNextWindowClass) on success would
+  prevent further filter from running, namely the one that prevent docking over a popup.
+- Backends: GLFW: Fixed an assertion in situation where the WndProc handler is different between
+  main and secondary viewport (may happen due to third-party hooks). (#6889)
+- Backends: DX9: Fixed incorrect assert triggering on reopening session with minimized windows. (#3424)
+
 
 -----------------------------------------------------------------------
  VERSION 1.89.9 (Released 2023-09-04)
@@ -2957,6 +3305,11 @@
 - Examples: Emscripten+WebGPU: Fixed WGPUInstance creation process + use preferred
   framebuffer format. (#6640, #6748) [@smileorigin]
 
+Docking+Viewports Branch:
+
+- Docking: when io.ConfigDockingWithShift is enabled, staying stationary while moving
+  a window displays an help tooltip to increase affordance. (#6709, #4643)
+
 
 -----------------------------------------------------------------------
  VERSION 1.89.8 (Released 2023-08-01)
@@ -3025,6 +3378,16 @@
 - Examples: Vulkan: Creating minimal descriptor pools to fit only what is needed by
   example. (#6642) [@SaschaWillem]
 
+Docking+Viewports Branch:
+
+- Docking, Style: resizing separators use same colors as window borders (ImGuiCol_Border)
+  for consistency. With default styles it doesn't make a big difference. (#2522) [@rmitton]
+  In the future if we promote using thick value for inner/outer docking padding we may
+  need to introduce new colors for it.
+- Docking: added style.DockingSeparatorSize, ImGuiStyleVar_DockingSeparatorSize. Now
+  also scaled by style.ScaleAllSizes(). (#3481, #4721, #2522) [@PossiblyAShrub, @wobbier]
+- Docking: fixed rendering of docked-window scrollbar above outer border. (#2522)
+
 
 -----------------------------------------------------------------------
  VERSION 1.89.7 (Released 2023-07-04)
@@ -3120,6 +3483,23 @@
 - Examples: Win32+OpenGL3: Changed DefWindowProc() to DefWindowProcW() to match other examples
   and support the example app being compiled without UNICODE. (#6516, #5725, #5961, #5975) [@yenixing]
 
+Docking+Viewports Branch:
+
+- Viewports+Docking: Fixed extraneous viewport+platform-window recreation in various
+  combination of showing or hiding windows, docking with/without split, undocking.
+  While with some backends and without OS decorations, some extraneous window recreation
+  were visibly not noticeable, they would typically become noticeable when enabling
+  OS decorations on those windows (e.g. Windows title bar fade-in/animation).
+- Viewports: Closing a viewport via OS/platform means (e.g. OS close button or task-bar menu),
+  mark all windows in this viewport as closed.
+- Docking: Fixed one-frame flickering on reappearing windows binding to a dock node
+  where a later-submitted window was already bound.
+- Docking: Fixed dragging from title-bar empty space (regression from 1.88 related to
+  keeping ID alive when calling low-level ButtonBehavior() directly). (#5181, #2645)
+- Docking: [Internal] DockBuilderDockWindow() API calls don't clear docking order
+  if the target node is same as existing one.
+- Backends: Win32: Added support for changing ParentViewportID after viewport creation.
+
 
 -----------------------------------------------------------------------
  VERSION 1.89.6 (Released 2023-05-31)
@@ -3189,6 +3569,23 @@
 - Examples: Added SDL3+SDL_Renderer example. (#6286)
 - Examples: Updated all Visual Studio projects and batches to use /utf-8 argument.
 
+Docking+Viewports Branch:
+
+- Viewports: Fixed platform-side focus (e.g. Alt+Tab) from leading to accidental
+  closure of Modal windows. Regression from 1.89.5. (#6357, #6299)
+- Viewports: Fixed loss of imgui-side focus when dragging a secondary viewport back in
+  main viewport, due to platform-side handling changes. Regression from 1.89.5 (#6299)
+- Viewports: Avoid applying imgui-side focus when focus change is due to a viewport
+  destruction. Fixes erroneous popup closure on closing a previous popup. (#6462, #6299)
+- Viewports: Added void* ImGuiPlatformMonitor::PlatformHandle field (backend-dependant),
+  for usage by user code.
+- Backends: GLFW: Preserve monitor list when there are no monitor, may briefly
+  happen when recovering from macOS sleeping mode. (#5683) [@Guistac]
+- Backends: SDL2: Update monitor list when receiving a display event. (#6348)
+  Note however that SDL2 currently doesn't have an event for a DPI/Scaling change,
+  so monitor data won't be updated in this situation.
+- Backends: SDL3: Update monitor list when receiving a display event. (#6348)
+
 
 -----------------------------------------------------------------------
  VERSION 1.89.5 (Released 2023-04-13)
@@ -3246,7 +3643,6 @@
   is to other IME function such as SDL_SetTextInputRect(). (#6306, #6071, #1953)
 - Backends: GLFW: Added support on Win32 only for io.AddMouseSourceEvent() to discriminate
   Mouse/TouchScreen/Pen. (#2334, #2702)
-- Backends: GLFW: Fixed key modifiers handling on secondary viewports. (#6248, #6034) [@aiekick]
 - Backends: Android: Added support for io.AddMouseSourceEvent() to discriminate Mouse/TouchScreen/Pen.
   (#6315) [@PathogenDavid]
 - Backends: OSX: Added support for io.AddMouseSourceEvent() to discriminate Mouse/Pen.
@@ -3262,6 +3658,16 @@
 - TestSuite: Added variety of new regression tests and improved/amended existing ones
   in imgui_test_engine/ repo. [@PathogenDavid, @ocornut]
 
+Docking+Viewports Branch:
+
+- Viewports: Setting focus from Platform/OS (e.g. via decoration, or Alt-Tab) sets corresponding
+  focus at Dear ImGui level (generally last focused window in the viewport). (#6299)
+- Docking: Fixed using GetItemXXX() or IsItemXXX() functions after a DockSpace(). (#6217)
+- Backends: GLFW: Fixed key modifiers handling on secondary viewports. (#6248, #6034) [@aiekick]
+- Backends: GLFW: Fixed Emscripten erroneously enabling multi-viewport support, leading to assert. (#5683)
+- Backends: SDL2/SDL3: Fixed IME text input rectangle position with viewports. (#6071, #1953)
+- Backends: SDL3: Fixed for compilation with multi-viewports. (#6255) [@P3RK4N]
+
 
 -----------------------------------------------------------------------
  VERSION 1.89.4 (Released 2023-03-14)
@@ -3336,7 +3742,6 @@
   and ImGuiConfigFlags_NavEnableGamepad by default. (#787)
 - Internals: Misc tweaks to facilitate applying an explicit-context patch. (#5856) [@Dragnalith]
 
-
 -----------------------------------------------------------------------
  VERSION 1.89.3 (Released 2023-02-14)
 -----------------------------------------------------------------------
@@ -3437,6 +3842,10 @@
 - Examples: SDL2+SDL_Renderer: Added call to SDL_RenderSetScale() to fix display on a
   Retina display (albeit lower-res as our other unmodified examples). (#6121, #6065, #5931).
 
+Docking+Viewports Branch:
+
+- Backends: GLFW: Handle unsupported glfwGetVideoMode() for Emscripten. (#6096)
+
 
 -----------------------------------------------------------------------
  VERSION 1.89.2 (Released 2023-01-05)
@@ -3487,6 +3896,17 @@
 - Backends: Vulkan: Fixed sampler passed to ImGui_ImplVulkan_AddTexture() not being honored as we were using
   an immutable sampler. (#5502, #6001, #914) [@martin-ejdestig, @rytisss]
 
+Docking+Viewports Branch:
+
+- Docking: Internals: fixed DockBuilderCopyDockSpace() crashing when windows not in the
+  remapping list are docked on the left or top side of a split. (#6035)
+- Docking: fixed DockSpace() with ImGuiDockNodeFlags_KeepAliveOnly marking current window
+  as written to, even if it doesn't technically submit an item. This allow using KeepAliveOnly
+  from any window location. (#6037)
+- Backends: OSX: fixed typo in ImGui_ImplOSX_GetWindowSize that would cause issues when resiing
+  from OS decorations, if they are enabled on secondary viewports. (#6009) [@sivu]
+- Backends: Metal: fixed secondary viewport rendering. (#6015) [@dmirty-kuzmenko]
+
 
 -----------------------------------------------------------------------
  VERSION 1.89.1 (Released 2022-11-24)
@@ -3513,6 +3933,13 @@
 - Backends: GLFW: cancel out errors emitted by glfwGetKeyName() when a name is missing. (#5908)
 - Backends: WebGPU: fixed validation error with default depth buffer settings. (#5869, #5914) [@kdchambers]
 
+Docking+Viewports Branch:
+
+- Viewports: Fixed collapsed windows setting ImGuiViewportFlags_NoRendererClear without
+  making title bar color opaque, leading to potential texture/fb garbage being visible.
+  Right now as we don't fully support transparent viewports (#2766), so we turn that
+  'TitleBgCollapsed' color opaque just lke we do for 'WindowBG' on uncollapsed windows.
+
 
 -----------------------------------------------------------------------
  VERSION 1.89 (Released 2022-11-15)
@@ -3704,6 +4131,23 @@
 - Backends: Vulkan: Added experimental ImGui_ImplVulkan_RemoveTexture() for api symmetry. (#914, #5738).
 - Backends: WebGPU: fixed rendering when a depth buffer is enabled. (#5869) [@brainlag]
 
+Docking+Viewports Branch:
+
+- Docking: Fixed incorrect focus highlight on docking node when focusing a menu. (#5702)
+- Docking, Nav: Fixed using gamepad/keyboard navigation not being able enter menu layer when
+  it only contained the standard Collapse/Close buttons and no actual menu. (#5463, #4792)
+- Docking: Fixed regression introduced in v1.87 when docked window content not rendered
+  while switching between with CTRL+Tab. [@rokups]
+- Docking: Fixed amending into an existing tab bar from rendering invisible items. (#5515)
+- Docking: Made spacing between dock nodes not a dropping gap. When hovering it only
+  outer-docking drop markers are visible.
+- Docking+Viewports: Fixed undocking window node causing parent viewports to become unresponsive
+  in certain situation (e.g. hidden tab bar). (#5503) [@rokups]
+- Backends: SDL: Fixed building backend under non-OSX Apple targets (e.g. iPhone). (#5665)
+- Backends: SDL: Fixed drag'n drop crossing a viewport border losing mouse coordinates. (#5710, #5012)
+- Backends: GLFW: Fixed leftover static variable preventing from changing or
+  reinitializing backend while application is running. (#4616, #5434) [@rtoumazet]
+
 
 -----------------------------------------------------------------------
  VERSION 1.88 (Released 2022-06-21)
@@ -3838,6 +4282,26 @@
 - Examples: Emscripten+WebGPU: Fix building for latest WebGPU specs. (#3632)
 - Examples: OSX+Metal, OSX+OpenGL: Removed now-unnecessary calls to ImGui_ImplOSX_HandleEvent(). (#4821)
 
+Docking+Viewports Branch:
+
+- Docking: Fixed floating docked nodes not being clamped into viewport workrect to stay reachable
+  when io.ConfigWindowsMoveFromTitleBarOnly is true and multi-viewports are disabled. (#5044)
+- Docking: Fixed a regression where moving window would be interrupted after undocking a tab
+  when io.ConfigDockingAlwaysTabBar is true. (#5324) [@rokups]
+- Docking: Fixed incorrect focus highlight on docking node when focusing empty central node
+  or a child window which was manually injected into a dockspace window.
+- Docking, Modal: Fixed a crash when opening popup from a parent which is being docked on the same frame. (#5401)
+- Viewports: Fixed an issue where MouseViewport was lagging by a frame when using 1.87 Input Queue.
+  A common side-effect would be that when releasing a window drag the underlying window would highlight
+  for a frame. (#5837, #4921) [@cfillion]
+- Viewports: Fixed translating a host viewport from briefly altering the size of AlwaysAutoResize windows. (#5057)
+- Viewports: Fixed main viewport size not matching ImDrawData::DisplaySize for one frame during resize
+  when multi-viewports are disabled. (#4900)
+- Backends: SDL: Fixed dragging out main viewport broken on some SDL setups. (#5012) [@rokups]
+- Backends: OSX: Added support for multi-viewports. [@stuartcarnie, @metarutaiga] (#4821, #2778)
+- Backends: Metal: Added support for multi-viewports. [@stuartcarnie, @metarutaiga] (#4821, #2778)
+- Examples: OSX+Metal, SDL+Metal, GLFW+Metal: Added support for multi-viewports. [@rokups]
+
 
 -----------------------------------------------------------------------
  VERSION 1.87 (Released 2022-02-07)
@@ -3981,6 +4445,29 @@
 - Backends: WebGPU: Fixed incorrect size parameters in wgpuRenderPassEncoderSetIndexBuffer() and
   wgpuRenderPassEncoderSetVertexBuffer() calls. (#4891) [@FeepsDev]
 
+Docking+Viewports Branch:
+
+- Docking: Fixed a CTRL+TAB crash when aiming at an empty docked window. (#4792)
+- Docking: Tabs use their own identifier instead of the Window identifier.
+  (This will invalidate some stored .ini data such as last selected tab, sorry!)
+- Docking: Fixed size constraints not working on single window holding on a dock id (still doesn't work on docked windows).
+- Docking: Fixed CTRL+TAB back into a docked window not selecting menu layer when no item are on main layer.
+- Viewports, IO: Added io.AddMouseViewportEvent() function to queue hovered viewport change (when known by backend).
+- Viewports: Relaxed specs for backend supporting ImGuiBackendFlags_HasMouseHoveredViewport: it is now _optional_
+  for the backend to have to ignore viewports with the _NoInputs flag when call io.AddMouseViewportEvent(). It is
+  much better if they can (Win32 and GLFW 3.3+ backends can, SDL and GLFW 3.2 backends cannot, they are lacking data).
+  A concrete example is: when dragging a viewport for docking, the viewport is marked with _NoInputs to allow us
+  to pick the target viewports for docking. If the backend reports a viewport with _NoInputs when calling the
+  io.AddMouseViewportEvent() function, then Dear ImGui will revert to its flawed heuristic to find the viewport under.
+  By lowering those specs, we allow the SDL and more backend to support this, only relying on the heuristic in a few
+  drag and drop situations rather that relying on it everywhere.
+- Viewports: Fixed a CTRL+TAB crash with viewports enabled when the window list needs to appears in
+  its own viewport (regression from 1.86). (#4023, #787)
+- Viewports: Fixed active InputText() from preventing viewports to merge. (#4212)
+- Backends: SDL: Added support for ImGuiBackendFlags_HasMouseHoveredViewport now that its specs have been lowered.
+- (Breaking) Removed ImGuiPlatformIO::Platform_SetImeInputPos() in favor of newly standardized
+  io.SetPlatformImeDataFn() function. Should not affect more than default backends.
+
 
 -----------------------------------------------------------------------
  VERSION 1.86 (Released 2021-12-22)
@@ -4079,6 +4566,24 @@
   wgpuRenderPassEncoderSetIndexBuffer() functions as validation layers appears to not do what the
   in-flux specs says. (#4766) [@meshula]
 
+Docking+Viewports Branch:
+
+- Docking: Revert removal of io.ConfigDockingWithShift config option (removed in 1.83). (#4643)
+- Docking: Fixed a bug undocking windows docked into a non-visible or _KeepAliveOnly dockspace
+  when unrelated windows submitted before the dockspace have dynamic visibility. (#4757)
+- Docking, Style: Docked windows honor ImGuiCol_WindowBg. (#2700, #2539)
+- Docking, Style: Docked windows honor display their border properly. (#2522)
+- Docking: Fixed incorrectly rounded tab bars for dock node that are not at the top of their dock tree.
+- Docking: Fixed single-frame node pos/size inconsistencies when window stop or start being submitted.
+- Docking: Prevent docking any window created above a popup/modal. (#4317)
+- Viewports: Made it possible to explicitly assign ImGuiWindowClass::ParentViewportId to 0 in order
+  to ensure a window is not parented. Previously this would use the global default (which might be 0,
+  but not always as it would depend on io.ConfigViewportsNoDefaultParent). (#3152, #2871)
+- Viewports: Fixed tooltip in own viewport over modal from being incorrectly dimmed. (#4729)
+- Viewports: Fixed CTRL+TAB highlight outline on docked windows not always fitting in host viewport.
+- Backends: Made it possible to shutdown default Platform Backends before the Renderer backends. (#4656)
+- Disabled: Fixed nested BeginDisabled()/EndDisabled() bug in Docking branch due to bad merge. (#4655, #4452, #4453, #4462)
+
 
 -----------------------------------------------------------------------
  VERSION 1.85 (Released 2021-10-12)
@@ -4097,6 +4602,10 @@
   Can use 'GetWindowContentRegionMax().x - GetWindowContentRegionMin().x' instead but it's not
   very useful in practice, and the only use of it in the demo was illfit.
   Using 'GetContentRegionAvail().x' is generally a better choice.
+- (Docking branch) IsWindowFocused() and IsWindowHovered() with only the _ChildWindows flag
+  and without the _RootWindow flag used to leak docking hierarchy, so a docked window would
+  return as the child of the window hosting the dockspace. This was inconsistent and incorrect
+  with other behaviors so we fixed it. Added a new _DockHierarchy flag to opt-in this behavior.
 
 Other Changes:
 
@@ -4170,6 +4679,29 @@
 - Backends: All renderers: Normalize clipping rect handling across backends. (#4464)
 - Examples: Added SDL + SDL_Renderer example in "examples/example_sdl_sdlrenderer/" folder. (#3926) [@1bsyl]
 
+Docking+Viewports Branch:
+
+- IsWindowFocused: Fixed using ImGuiFocusedFlags_ChildWindows (without _RootWindow) from leaking the
+  docking hierarchy. Added ImGuiFocusedFlags_DockHierarchy flag to consider docking hierarchy in the test.
+- IsWindowHovered: Fixed using ImGuiHoveredFlags_ChildWindows (without _RootWindow) from leaking the
+  docking hierarchy. Added ImGuiHoveredFlags_DockHierarchy flag to consider docking hierarchy in the test.
+- Nav: Fixed an issue with losing focus on docked windows when pressing Alt while keyboard navigation
+  is disabled. (#4547, #4439) [@PathogenDavid]
+- Docking: Fixed IsItemHovered() and functions depending on it (e.g. BeginPopupContextItem()) when
+  called after Begin() on a docked window (broken 2021/03/04). (#3851)
+- Docking: Improved resizing system so that non-central zone are better at keeping their fixed size.
+  The algorithm is still not handling the allocation of size ideally for nested sibling, but it got better.
+- Docking: Fixed settings load issue when mouse wheeling. (#4310)
+- Docking: Fixed manually created floating node with a central node from not hiding when windows are gone.
+- Docking + Drag and Drop: Fixed using BeginDragDropSource() or BeginDragDropTarget() inside a Begin()
+  that returned false because the window is docked. (#4515)
+- Viewports: Fixed a crash while a window owning its viewport disappear while being dragged.
+  It would manifest when e.g. reconfiguring dock nodes while dragging.
+- Viewports: Fixed unnecessary creation of temporary viewports when multiple docked windows
+  got reassigned to a new node (created mid-frame) which already has a HostWindow.
+- Viewports: Fixed window with viewport ini data immediately merged into a host viewport from
+  leaving a temporary viewport alive for a frame (would leak into backend).
+
 
 -----------------------------------------------------------------------
  VERSION 1.84.2 (Released 2021-08-23)
@@ -4306,6 +4838,25 @@
 - Examples: Updated all .vcxproj to VS2015 (toolset v140) to facilitate usage with vcpkg.
 - Examples: SDL2: Accommodate for vcpkg install having headers in SDL2/SDL.h vs SDL.h.
 
+Docking+Viewports Branch:
+
+- Docking: Clicking on the right-most close button of a docking node closes all windows. (#4186)
+- Docking: Fix IsWindowAppearing() and ImGuiCond_Appearing on docked windows. (#4177, #3982, #1497, #1061)
+- Docking: Fix crash using DockBuilderRemoveNode() in some situations. (#3111, #3179, #3203, #4295) [@hsimyu]
+- Docking: Fix crash when a dock node gets re-qualified as dockspace>floating>dockspace, which tends to happen
+  when incorrectly calling DockBuilderAddNode() without ImGuiDockNodeFlags_Dockspace and using it as a Dockspace
+  on the next frame after the floating window hosting the node has been automatically created. (#3203, #4295)
+- Docking: Reworked node flags saving/inheritance so that flags enforced by docked windows via the
+  DockNodeFlagsOverrideSet mechanism are are not left in empty dockspace nodes once the windows gets undocked.
+  (#4292, #3834, #3633, #3521, #3492, #3335, #2999, #2648)
+- Docking: (Internal/Experimental) Removed DockNodeFlagsOverrideClear flags from ImGuiWindowClass as
+  it is ambiguous how to apply them and we haven't got a use out of them yet.
+- Docking: Fixed ImGuiWindowFlags_UnsavedDocument clipping label in docked windows when there are
+  no close button. (#5745)
+- Viewports: Fix popup/tooltip created without a parent window from being given a ParentViewportId value
+  from the implicit/fallback window. (#4236, #2409)
+- Backends: Vulkan: Fix the use of the incorrect fence for secondary viewports. (#4208) [@FunMiles]
+
 
 -----------------------------------------------------------------------
  VERSION 1.83 (Released 2021-05-24)
@@ -4390,6 +4941,22 @@
 - Docs: Improvements to description of using colored glyphs/emojis. (#4169, #3369)
 - Docs: Improvements to minor mistakes in documentation comments (#3923) [@ANF-Studios]
 
+Docking+Viewports Branch:
+
+- [Breaking] Removed io.ConfigDockingWithShift config option. Behavior always equivalent to having the
+  option set to false (dock/undock by default, hold shift to avoid docking). (#2109)
+- Docking: DockSpace() returns its node ID.
+- Docking: Dockspace() never draws a background. (#3924)
+- Docking: Undocking nodes/windows covering most of the monitor max their size down to 90% to ease manipulations.
+- Docking: Docking node tab bar honors ItemInnerSpacing.x before first tab. (#4130)
+- Docking: Tweak rendering and alignment of dock node menu marker. (#4130)
+- Docking: Fixed restoring of tab order within a dockspace or a split node.
+- Docking: Fixed reappearing docked windows with no close button showing a tab with extraneous space for one frame.
+- Docking: Fixed multiple simultaneously reappearing window from appearing undocked for one frame.
+- Viewports: Hotfix for crash in monitor array access, caused by 4b9bc4902. (#3967)
+- Backends, Viewports: GLFW: Add a workaround for stuck keys after closing a GLFW window (#3837).
+- Backends, Viewports: Vulkan: Rebuild swapchain on VK_SUBOPTIMAL_KHR. (#3881)
+
 
 -----------------------------------------------------------------------
  VERSION 1.82 (Released 2021-02-15)
@@ -4485,6 +5052,13 @@
   scheduled builds builds are not required. [@rokups]
 - Log/Capture: Added LogTextV, a va_list variant of LogText. [@PathogenDavid]
 
+Docking+Viewports Branch:
+
+- Viewports: Fix setting of ImGuiViewportFlags_NoRendererClear. (#3213)
+- Viewports: Added GetViewportPlatformMonitor() with a safety net to keep code portable.
+- Viewports, Backends: SDL: Fix missing ImGuiBackendFlags_HasSetMousePos flag in docking branch.
+- Viewports, Backends: GLFW: Fix application of WantSetMousePos. (#1542, #787)
+
 
 -----------------------------------------------------------------------
  VERSION 1.81 (Released 2021-02-10)
@@ -4566,6 +5140,17 @@
 - Examples: WebGPU: Added Emscripten+WebGPU example. (#3632) [@bfierz]
 - Backends: GLFW: Added ImGui_ImplGlfw_InitForOther() initialization call to use with non OpenGL API. (#3632)
 
+Docking+Viewports Branch:
+
+- Docking: Fix losing docking information on closed windows for which the hosting node was split. (#3716) [@GamingMinds-DanielC]
+- Docking: Fix gap in hit test hole when using ImGuiDockNodeFlags_PassthruCentralNode touching the edge of a viewport. (#3733)
+- Viewports: (Breaking) removed ImGuiPlatformIO::MainViewport which is now pretty much unused and duplicate
+  (and misleading as we will evolve the concept).
+- Viewports: (Breaking) turned ImGuiViewport::GetWorkPos(), ImGuiViewport::GetWorkSize() into regular fields
+  (WorkPos, WorkSize) before exposing in master branch.
+- Viewports: Fix issue inferring viewport z-order when new popups gets created. (#3734) + Metrics updates.
+- Viewports, Backends: Vulkan: handle VK_ERROR_OUT_OF_DATE_KHR when resizing secondary viewport (#3766, #3758)
+
 
 -----------------------------------------------------------------------
  VERSION 1.80 (Released 2021-01-21)
@@ -4685,6 +5270,14 @@
 - Docs: Split examples/README.txt into docs/BACKENDS.md and docs/EXAMPLES.md, and improved them.
 - Docs: Consistently renamed all occurrences of "binding" and "back-end" to "backend" in comments and docs.
 
+Docking+Viewports Branch:
+
+- Docking: Docked windows honor change of tab and text colors. (#2771)
+- Docking: Support for appending into existing tab-bar made to work with Docking + internal helper DockNodeBeginAmendTabBar().
+- Docking: Added experimental TabItemFlagsOverrideSet to ImGuiWindowClass.
+- Viewports: Fixed incorrect whitening of popups above a modal if both use their own viewport.
+- Viewports: Backends: Vulkan: Fixed build, removed extraneous pipeline creation. (#3459, #3579)
+
 
 -----------------------------------------------------------------------
  VERSION 1.79 (Released 2020-10-08)
@@ -4779,6 +5372,21 @@
 - Examples: DX12: Added '#define ImTextureID ImU64' in project and build files to also allow building
   on 32-bit systems. Added project to default Visual Studio solution file. (#301)
 
+Docking+Viewports Branch:
+
+- Docking: DockSpace() emits ItemSize() properly (useful when not filling all space).
+- Docking: Fixed docking while hovering a child window. (#3420) broken by 85a661d. Improve metrics debugging.
+- Docking: Fix honoring payload filter with overlapping nodes (we incorrectly over-relied on g.HoveredDockNode
+  when making change for #3398).
+- Docking: Fix handling of WindowMenuButtonPosition == ImGuiDir_None in Docking Nodes. (#3499)
+- Viewports: Fixed a rare edge-case if the window targeted by CTRL+Tab stops being rendered.
+- Viewports, Backends: DX12: Make secondary viewport format match main viewport one (#3462) {@BeastLe9enD]
+- Viewports: Backends: Vulkan: Removed unused shader code. Fix leaks. Avoid unnecessary pipeline creation for main
+  viewport. (#3459) + Add ImGui_ImplVulkanH_CreateWindowSwapChain in ImGui_ImplVulkanH_CreateOrResizeWindow().
+- Viewports: Backends: DirectX9: Recover from D3DERR_DEVICELOST on secondary viewports. (#3424)
+- Viewports, Backends: Win32: Fix toggling of ImGuiViewportFlags_TopMost (#3477) [@Kodokuna]
+- Viewports: Backends: GLFW: Workaround for cases where glfwGetMonitorWorkarea fails (#3457) [@dougbinks]
+
 
 -----------------------------------------------------------------------
  VERSION 1.78 (Released 2020-08-18)
@@ -4880,6 +5488,23 @@
 - Examples: Vulkan: Fixed GLFW+Vulkan and SDL+Vulkan clear color not being set. (#3390) [@RoryO]
 - CI: Emscripten has stopped their support for their fastcomp backend, switching to latest sdk [@Xipiryon]
 
+Docking+Viewports Branch:
+
+- Docking: Made DockBuilderAddNode() automatically call DockBuilderRemoveNode(). (#3399, #2109)
+- Docking: Storing HoveredDockNode in context which can be useful for easily detecting e.g. hovering an
+  empty node. (#3398)
+- Docking: Fixed docking overlay bits appearing at (0,0), because of 43bd80a. Most typically noticeable
+  when disabling multi-viewport.
+- Docking: Workaround recovery for node created without the _DockSpace flags later becoming a DockSpace. (#3340)
+- Docking: Rework size allocations to recover when there's no enough room for nodes + do not hold on
+  _WantLockSizeOnce forever. (#3328)
+- Docking: Rework size allocation to allow user code to override node sizes. Not all edge cases will be
+  properly handled but this is a step toward toolbar emitting size constraints.
+- Docking: Added experimental flags to perform more docking filtering and disable resize per axis.
+  Designed for toolbar patterns.
+- Viewports, Backends, GLFW: Use GLFW_MOUSE_PASSTHROUGH when available.
+- Viewports, Backends: DX12: Fixed issue on shutdown when viewports are disabled. (#3347)
+
 
 -----------------------------------------------------------------------
  VERSION 1.77 (Released 2020-06-29)
@@ -4971,6 +5596,17 @@
 - Examples: Apple: Fixed example_apple_metal and example_apple_opengl2 using imgui_impl_osx.mm
   not forwarding right and center mouse clicks. (#3260) [@nburrus]
 
+Docking+Viewports Branch:
+
+- Viewports: Don't set ImGuiViewportFlags_NoRendererClear when ImGuiWindowFlags_NoBackground is set. (#3213)
+- Viewports: Report minimized viewports as zero DisplaySize to be consistent with main branch. (#1542)
+- Docking, Settings: Allow reload of settings data at runtime. (#2573)
+- Backends, GLFW: Fix windows resizing incorrectly on Linux due to GLFW firing window positioning
+  callbacks on next frame after window is resized manually. (#2117)
+- Backends: DX12: Fix OBJECT_DELETED_WHILE_STILL_IN_USE on viewport resizing. (#3210)
+- Backends: DX12: Fix for crash caused by early resource release. (#3121)
+- Backends, Win32: Request monitor update when DPI awareness is enabled to make sure they have the correct DPI settings.
+
 
 -----------------------------------------------------------------------
  VERSION 1.76 (Released 2020-04-12)
@@ -5043,6 +5679,20 @@
 - Examples: SDL+DX11: Fixed resizing main window. (#3057) [@joeslay]
 - Examples: Added SDL+Metal example application. (#3017) [@coding-jackalope]
 
+Docking+Viewports Branch:
+
+- Docking: Fixed assert preventing dockspace from being created instead a hidden tab. (#3101)
+- Viewports: Fixed secondary viewports accidentally merging into a minimized host viewport. (#3118)
+- Viewports, Docking: Added per-viewport work area system for e.g. menu-bars. Fixed DockspaceOverViewport()
+  and demo code (overlay etc) accordingly. (#3035, #2889, #2474, #1542, #2109)
+- Viewports: Improve menu positioning in multi-monitor setups. [@rokups]
+- Viewports: Software mouse cursor is also scaled by current DpiScale. (amend #939)
+- Viewports: Avoid manually clipping resize grips and borders, which messes up with automation ability
+  to locate those items. Also simpler and more standard.
+- Viewports: Fix for UWP in the imgui_impl_win32.cpp IME handler. (#2895, #2892).
+- Viewports: Bunch of extra of comments to facilitate setting up multi-viewports.
+- Viewports, GLFW: Avoid using window positioning workaround for GLFW 3.3+ versions that have it fixed.
+
 
 -----------------------------------------------------------------------
  VERSION 1.75 (Released 2020-02-10)
@@ -5141,6 +5791,21 @@
 - Examples: Metal: Wrapped main loop in @autoreleasepool block to ensure allocations get freed
   even if underlying system event loop gets paused due to app nap. (#2910, #2917) [@bear24rw]
 
+Docking+Viewports Branch:
+
+- Docking + Nav: Fixed messed up Ctrl+Tab order with docked windows.
+- Docking + Nav: Fixed failing to restore NavId when refocusing a child within a docked window.
+- Docking + Nav: Fixed failing to restore NavId when refocusing due to missing nav window (when
+  it stops being submitted).
+- Docking: Fixed a bug where the tab bar of a hidden dockspace would keep requesting focus. (#2960)
+- Docking: Added experimental DockNodeFlagsOverrideSet/DockNodeFlagsOverrideClear flags in ImGuiWindowClass
+  (currently experimenting with toolbar idioms).
+- Viewports: Fix resizing viewport-owning windows when mouse pos is outside the InnerClipRect
+  (can happen with OS decoration enabled).
+- Viewports: Preserve last known size for minimized main viewport to be consistent with secondary viewports.
+- Backends: SDL: Honor NoTaskBarIcon flag under non Win32 OS. (#2117)
+- Backends: GLFW, SDL: Platform monitors declared properly even if multi-viewport is not enabled.
+
 
 -----------------------------------------------------------------------
  VERSION 1.74 (Released 2019-11-25)
@@ -5220,6 +5885,14 @@
 - CI: Set up a bunch of continuous-integration tests using GitHub Actions. We now compile many of the example
   applications on Windows, Linux, MacOS, iOS, Emscripten. Removed Travis integration. (#2865) [@rokups]
 
+Docking+Viewports Branch:
+
+- Docking: Can undock from the small triangle button. (#2109,. #2645)
+- Docking: Fixed node->HasCloseButton not honoring ImGuiDockNodeFlags_NoCloseButton in a floating node,
+  leading to empty space at the right of tab-bars with those flags. (#2109)
+- Docking: Made docked windows not use style.ChildRounding.
+- Multi-viewports: Added multi-viewport support in the DX12 back-end. (#2851) [@obfuscate]
+
 
 -----------------------------------------------------------------------
  VERSION 1.73 (Released 2019-09-24)
@@ -5282,6 +5955,28 @@
 - Misc: Updated stb_rect_pack.h from 0.99 to 1.00 (fixes by @rygorous: off-by-1 bug in best-fit heuristic,
   fix handling of rectangles too large to fit inside texture). (#2762) [@tido64]
 
+Docking+Viewports Branch:
+
+- Docking: Fix BeginDocked() path that creates node so that SetNextWindowDockID() doesn't immediately discard the node. (#2109)
+- Docking: Fix for node created at the same time as windows that are still resizing (typically with
+  io.ConfigDockingAlwaysTabBar) to not be zero/min sized. (#2109). The fix delays their visibility by one frame,
+  which is not ideal but not very problematic as the .ini data gets populated after that.
+- Docking: Fix a crash that could occur with a malformed ini file (DockNode Parent value pointing to a missing node).
+- Viewport: Fix modal/popup window being stuck in unowned hidden viewport associated to fallback window without stealing
+  it back. Fix modal reference viewport when opened outside of another window. (#1542)
+- Viewport: Modals don't need to set ImGuiViewportFlags_NoFocusOnClick, this also mitigate the issue described by #2445,
+  which becomes particularly bad with unfocused modal. (#1542)
+- Viewport: better case case where host window gets moved and resized simultaneous (toggling maximized state).
+  There's no perfect solution there, than using io.ConfigViewportsNoAutoMerge = false. (#1542)
+- Viewport, Docking: Fixed incorrect assignment of IsFallbackWindow which would tag dock node host windows created
+  in NewFrame() as such, messing with popup viewport inheritance.
+- Viewport: Fixed issue where resize grip would display as hovered while mouse is still off the OS bounds so a click
+  would miss it and focus the OS window behind expected one. (#1542)
+- Viewport: Fix to allow multiple shutdown / calls to DestroyPlatformWindows(). (#2769)
+- Viewport: Backends: GLFW: Fix setting window size on macOS (#2767, #2117) [@rokups]
+- Viewport: Backends: GLFW+Linux: Fix window having incorrect size after uncollapse. (#2756, #2117) [@rokups]
+- Viewport: Backends: DirectX9: Workaround for windows not refreshing when main viewport has no draw call. (#2560)
+
 
 -----------------------------------------------------------------------
  VERSION 1.72b (Released 2019-07-31)
@@ -5384,6 +6079,25 @@
   (#2482, #2632) [@josiahmanson]
 - Examples: Added SDL2+DirectX11 example application. (#2632, #2612, #2482) [@vincenthamm]
 
+Docking+Viewports Branch:
+
+- Docking: Making it possible to undock a node by clicking on the tab bar / title bar for the node. (#2645).
+- Docking: Explicitly inhibit constraint when docked for now. Fix clipping issue related to constraints. (#2690).
+- Docking: Fixed dragging/resizing from OS decoration not marking settings as dirty.
+- Docking: Renamed io.ConfigDockingTabBarOnSingleWindows to io.ConfigDockingAlwaysTabBar.
+  Added ImGuiWindowClass::DockingAlwaysTabBar to set on individual windows.
+- Docking: Perform simple check: assert if Docking or Viewport are enabled exactly on frame 1 (instead of frame 0
+  or later), which is a common user error leading to loss of .ini data on load.
+- Docking: Fix so that an appearing window making a dock node reappear won't have a zero-size on its first frame.
+- Docking: Fixed using ImGuiDockNodeFlags_AutoHideTabBar with io.ConfigDockingTabBarOnSingleWindows.
+- Docking: Added ImGuiDockNode to .natvis file.
+- Docking: Fixed support for large meshes in GetBackgroundDrawList(), GetForegroundDrawList(). (#2638)
+- Viewport: Fix monitor dpi info not being copied to main viewport when multi-viewports are not enabled. (#2621, #1676)
+- Viewport: Refactored ImGuiWindowClass's ViewportFlagsOverrideMask + ViewportFlagsOverrideValue into
+  ViewportFlagsOverrideSet + ViewportFlagsOverrideClear which appears easier to grasp. (#1542)
+- Viewport: Added ImGuiViewportFlags_NoAutoMerge to prevent merging into host viewport in a per-window basis
+  via the ImGuiWindowClass override mechanism. (#1542)
+
 
 -----------------------------------------------------------------------
  VERSION 1.71 (Released 2019-06-12)
@@ -5723,6 +6437,7 @@
 - Renamed ImFontAtlas::GlyphRangesBuilder to ImFontGlyphRangesBuilder. Kept redirection typedef (will obsolete).
 
 Other Changes:
+
 - Added BETA api for Tab Bar/Tabs widgets: (#261, #351)
   - Added BeginTabBar(), EndTabBar(), BeginTabItem(), EndTabItem(), SetTabItemClosed() API.
   - Added ImGuiTabBarFlags flags for BeginTabBar().

diff --git a/docs/TODO.txt b/docs/TODO.txt
index 6107e5d..91d5bb5 100644
--- a/docs/TODO.txt
+++ b/docs/TODO.txt

@@ -123,7 +123,35 @@
  - separator: width, thickness, centering (#1643, #2657)
  - splitter: formalize the splitter idiom into an official api (we want to handle n-way split) (#319)
 
- - docking: merge docking branch (#2109)
+ - docking: B: ordering currently held in tab bar should be implicitly held by windows themselves (also see #2304)
+ - docking: B- tab bar: the order/focus restoring code could be part of TabBar and not DockNode? (#8)
+ - docking: B~ rework code to be able to lazily create tab bar instance in a single place. The _Unsorted tab flag could be replacing a trailing-counter in DockNode?
+ - docking: B~ fully track windows/settings reference in dock nodes. perhaps find a representation that allows facilitate use of dock builder functions.
+ - docking: B~ Unreal style document system (requires low-level controls of dockspace serialization fork/copy/delete). this is mostly working but the DockBuilderXXX api are not exposed/finished.
+ - docking: B: when docking outer, perform size locking on neighbors nodes the same way we do it with splitters, so other nodes are not resized.
+ - docking: B~ central node resizing behavior incorrect.
+ - docking: B: changing title font/style per-window is not supported as dock nodes are created in NewFrame.
+ - docking: B- dock node inside its own viewports creates 1 temporary viewport per window on startup before ditching them (doesn't affect the user nor request platform windows to be created, but unnecessary)
+ - docking: B- resize sibling locking behavior may be less desirable if we merged same-axis sibling in a same node level?
+ - docking: B- single visible node part of a hidden split hierarchy (OnlyNodeWithWindows != NULL) should show a normal title bar (not a tab bar)
+ - docking: B~ SetNextWindowDock() calls (with conditional) -> defer everything to DockContextUpdate (repro: Documents->[X]Windows->Dock 1 elsewhere->Click Redock All
+ - docking: B~ tidy up tab list popup buttons features (available with manual tab-bar, see ImGuiTabBarFlags_NoTabListPopupButton code, not used by docking nodes)
+ - docking: B- SetNextWindowDockId(0) with a second Begin() in the frame will asserts
+ - docking: B: resize grip drawn in host window typically appears under scrollbar.
+ - docking: B: resize grip auto-resize on multiple node hierarchy doesn't make much sense or should be improved?
+ - docking: B- SetNextWindowFocus() doesn't seem to apply if the window is hidden this frame, need repro (#4)
+ - docking: B- resizing a dock tree small currently has glitches (overlapping collapse and close button, etc.)
+ - docking: B- dpi: look at interaction with the hi-dpi and multi-dpi stuff.
+ - docking: B- tab bar: appearing on first frame with a dumb layout would do less harm that not appearing? (when behind dynamic branch) or store titles + render in EndTabBar()
+ - docking: B- tab bar: make selected tab always shows its full title?
+ - docking: B- hide close button on single tab bar?
+ - docking: B- nav: design interactions so nav controls can dock/undock
+ - docking: B- dockspace: flag to lock the dock tree and/or sizes (ImGuiDockNodeFlags_Locked?)
+ - docking: B- reintroduce collapsing a floating dock node. also collapsing a docked dock node!
+ - docking: B- allow dragging a non-floating dock node by clicking on the title-bar-looking section (not just the collapse/menu button)
+ - docking: B- option to remember undocked window size? (instead of keeping their docked size) (relate to #2104)
+ - docking: C- nav: CTRL+TAB highlighting tabs shows the mismatch between focus-stack and tab-order (not visible in VS because it doesn't highlight the tabs)
+ - docking: C- after a dock/undock, the Scrollbar Status update in Begin() should use an updated e.g. size_y_for_scrollbars to avoid a 1 frame scrollbar flicker.
 
  - tabs: "there is currently a problem because TabItem() will try to submit their own tooltip after 0.50 second, and this will have the effect of making your tooltip flicker once." -> tooltip priority work (WIP branch)
  - tabs: make EndTabBar fail if users doesn't respect BeginTabBar return value, for consistency/future-proofing.
@@ -286,6 +314,21 @@
  - nav/windowing: Resizing window will currently fail with certain types of resizing constraints/callback applied
  - focus: preserve ActiveId/focus stack state, e.g. when opening a menu and close it, previously selected InputText() focus gets restored (#622)
 
+ - viewport: make it possible to have no main/hosting viewport (see #8268)
+ - viewport: We set ImGuiViewportFlags_NoFocusOnAppearing in a way that is required for GLFW/SDL binding, but could be handled better without
+   on a custom e.g. Win32 bindings. It prevents newly dragged-out viewports from taking the focus, which makes ALT+F4 more ambiguous.
+ - viewport: not focusing newly undocked viewport means clicking back on previous one doesn't bring OS window to front.
+ - viewport: with platform decoration enabled, platform may force constraint (e.g. minimum size)
+ - viewport: use getfocus/setfocus api to synchronize imgui<>platform focus better (e.g imgui-side ctrl-tab can focus os window, OS initial setup and alt-tab can focus imgui window etc.)
+ - viewport: store per-viewport/monitor DPI in .ini file so an application reload or main window changing DPI on reload can be properly patched for.
+ - viewport: implicit/fallback Debug window can hog a zombie viewport (harmless, noisy?) > could at least clear out the reference on a per session basis?
+ - viewport: need to clarify how to use GetMousePos() from a user point of view.
+ - viewport: could apply monitor boundaries to cliprect to coarse clip things out of monitor? (#8698)
+ - platform: glfw: no support for ImGuiBackendFlags_HasMouseHoveredViewport.
+ - platform: sdl: no support for ImGuiBackendFlags_HasMouseHoveredViewport. maybe we could use SDL_GetMouseFocus() / SDL_WINDOW_MOUSE_FOCUS if imgui could fallback on its heuristic when NoInputs is set
+ - platform: sdl: no refresh of monitor/display (SDL doesn't seem to have an event for it).
+ - platform: sdl: multi-viewport + minimized window seems to break mouse wheel events (at least under Win32).
+
  - inputs: support track pad style scrolling & slider edit.
  - inputs/io: backspace and arrows in the context of a text input could use system repeat rate.
  - inputs/io: clarify/standardize/expose repeat rate and repeat delays (#1808)

diff --git a/examples/example_allegro5/main.cpp b/examples/example_allegro5/main.cpp
index ebb6d76..47d674a 100644
--- a/examples/example_allegro5/main.cpp
+++ b/examples/example_allegro5/main.cpp

@@ -40,6 +40,7 @@
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;      // Enable Docking
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();

diff --git a/examples/example_apple_metal/example_apple_metal.xcodeproj/project.pbxproj b/examples/example_apple_metal/example_apple_metal.xcodeproj/project.pbxproj
index bf3c80d..ab181bb 100644
--- a/examples/example_apple_metal/example_apple_metal.xcodeproj/project.pbxproj
+++ b/examples/example_apple_metal/example_apple_metal.xcodeproj/project.pbxproj

@@ -7,7 +7,10 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		050450AB2768052600AB6805 /* imgui_tables.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 5079822D257677DB0038A28D /* imgui_tables.cpp */; };
+		050450AD276863B000AB6805 /* QuartzCore.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 050450AC276863B000AB6805 /* QuartzCore.framework */; };
 		05318E0F274C397200A8DE2E /* GameController.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 05318E0E274C397200A8DE2E /* GameController.framework */; };
+		05A275442773BEA20084EF39 /* QuartzCore.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 05A275432773BEA20084EF39 /* QuartzCore.framework */; };
 		07A82ED82139413D0078D120 /* imgui_widgets.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 07A82ED72139413C0078D120 /* imgui_widgets.cpp */; };
 		07A82ED92139418F0078D120 /* imgui_widgets.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 07A82ED72139413C0078D120 /* imgui_widgets.cpp */; };
 		5079822E257677DB0038A28D /* imgui_tables.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 5079822D257677DB0038A28D /* imgui_tables.cpp */; };
@@ -33,7 +36,11 @@
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
+		050450AC276863B000AB6805 /* QuartzCore.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = QuartzCore.framework; path = System/Library/Frameworks/QuartzCore.framework; sourceTree = SDKROOT; };
 		05318E0E274C397200A8DE2E /* GameController.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = GameController.framework; path = System/Library/Frameworks/GameController.framework; sourceTree = SDKROOT; };
+		05A2754027728F5B0084EF39 /* imgui_impl_metal.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = imgui_impl_metal.h; path = ../../backends/imgui_impl_metal.h; sourceTree = "<group>"; };
+		05A2754127728F5B0084EF39 /* imgui_impl_osx.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = imgui_impl_osx.h; path = ../../backends/imgui_impl_osx.h; sourceTree = "<group>"; };
+		05A275432773BEA20084EF39 /* QuartzCore.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = QuartzCore.framework; path = Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk/System/Library/Frameworks/QuartzCore.framework; sourceTree = DEVELOPER_DIR; };
 		07A82ED62139413C0078D120 /* imgui_internal.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = imgui_internal.h; path = ../../imgui_internal.h; sourceTree = "<group>"; };
 		07A82ED72139413C0078D120 /* imgui_widgets.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = imgui_widgets.cpp; path = ../../imgui_widgets.cpp; sourceTree = "<group>"; };
 		5079822D257677DB0038A28D /* imgui_tables.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = imgui_tables.cpp; path = ../../imgui_tables.cpp; sourceTree = "<group>"; };
@@ -66,6 +73,7 @@
 			isa = PBXFrameworksBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				05A275442773BEA20084EF39 /* QuartzCore.framework in Frameworks */,
 				8309BD8F253CCAAA0045E2A1 /* UIKit.framework in Frameworks */,
 				83BBE9E720EB46BD00295997 /* MetalKit.framework in Frameworks */,
 				83BBE9E520EB46B900295997 /* Metal.framework in Frameworks */,
@@ -76,6 +84,7 @@
 			isa = PBXFrameworksBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				050450AD276863B000AB6805 /* QuartzCore.framework in Frameworks */,
 				8309BDC6253CCCFE0045E2A1 /* AppKit.framework in Frameworks */,
 				83BBE9EC20EB471700295997 /* MetalKit.framework in Frameworks */,
 				05318E0F274C397200A8DE2E /* GameController.framework in Frameworks */,
@@ -136,6 +145,8 @@
 		83BBE9E320EB46B800295997 /* Frameworks */ = {
 			isa = PBXGroup;
 			children = (
+				050450AC276863B000AB6805 /* QuartzCore.framework */,
+				05A275432773BEA20084EF39 /* QuartzCore.framework */,
 				05318E0E274C397200A8DE2E /* GameController.framework */,
 				8309BDC5253CCCFE0045E2A1 /* AppKit.framework */,
 				8309BD8E253CCAAA0045E2A1 /* UIKit.framework */,
@@ -153,7 +164,9 @@
 			isa = PBXGroup;
 			children = (
 				5079822D257677DB0038A28D /* imgui_tables.cpp */,
+				05A2754027728F5B0084EF39 /* imgui_impl_metal.h */,
 				8309BDB5253CCC9D0045E2A1 /* imgui_impl_metal.mm */,
+				05A2754127728F5B0084EF39 /* imgui_impl_osx.h */,
 				8309BDB6253CCC9D0045E2A1 /* imgui_impl_osx.mm */,
 				83BBEA0420EB54E700295997 /* imconfig.h */,
 				83BBEA0320EB54E700295997 /* imgui.cpp */,
@@ -285,7 +298,7 @@
 				83BBEA0A20EB54E700295997 /* imgui.cpp in Sources */,
 				83BBEA0820EB54E700295997 /* imgui_demo.cpp in Sources */,
 				83BBEA0620EB54E700295997 /* imgui_draw.cpp in Sources */,
-				5079822E257677DB0038A28D /* imgui_tables.cpp in Sources */,
+				050450AB2768052600AB6805 /* imgui_tables.cpp in Sources */,
 				07A82ED92139418F0078D120 /* imgui_widgets.cpp in Sources */,
 				8309BDA8253CCC080045E2A1 /* main.mm in Sources */,
 			);

diff --git a/examples/example_apple_metal/main.mm b/examples/example_apple_metal/main.mm
index b8edbd2..1f22d95 100644
--- a/examples/example_apple_metal/main.mm
+++ b/examples/example_apple_metal/main.mm

@@ -60,11 +60,21 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsLight();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Renderer backend
     ImGui_ImplMetal_Init(_device);
 
@@ -197,6 +207,13 @@
     // Present
     [commandBuffer presentDrawable:view.currentDrawable];
     [commandBuffer commit];
+
+    // Update and Render additional Platform Windows
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        ImGui::UpdatePlatformWindows();
+        ImGui::RenderPlatformWindowsDefault();
+    }
 }
 
 -(void)mtkView:(MTKView*)view drawableSizeWillChange:(CGSize)size

diff --git a/examples/example_apple_opengl2/main.mm b/examples/example_apple_opengl2/main.mm
index 1cfa882..68dfe71 100644
--- a/examples/example_apple_opengl2/main.mm
+++ b/examples/example_apple_opengl2/main.mm

@@ -6,6 +6,8 @@
 // - Documentation        https://dearimgui.com/docs (same as your local docs/ folder).
 // - Introduction, links and more at the top of imgui.cpp
 
+// FIXME: Multi-viewports is not yet functional in this example. May need backend rework/coordination.
+
 #import <Cocoa/Cocoa.h>
 #import <OpenGL/gl.h>
 #import <OpenGL/glu.h>
@@ -47,11 +49,21 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsLight();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Setup Platform/Renderer backends
     ImGui_ImplOSX_Init(self);
     ImGui_ImplOpenGL2_Init();
@@ -138,6 +150,13 @@
 
     ImGui_ImplOpenGL2_RenderDrawData(draw_data);
 
+    // Update and Render additional Platform Windows
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        ImGui::UpdatePlatformWindows();
+        ImGui::RenderPlatformWindowsDefault();
+    }
+
     // Present
     [[self openGLContext] flushBuffer];
 

diff --git a/examples/example_glfw_metal/main.mm b/examples/example_glfw_metal/main.mm
index 0ded0a3..fc5f026 100644
--- a/examples/example_glfw_metal/main.mm
+++ b/examples/example_glfw_metal/main.mm

@@ -44,6 +44,8 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -53,6 +55,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     id <MTLDevice> device = MTLCreateSystemDefaultDevice();
     id <MTLCommandQueue> commandQueue = [device newCommandQueue];
@@ -164,6 +175,13 @@
             ImGui::Render();
             ImGui_ImplMetal_RenderDrawData(ImGui::GetDrawData(), commandBuffer, renderEncoder);
 
+            // Update and Render additional Platform Windows
+            if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+            {
+                ImGui::UpdatePlatformWindows();
+                ImGui::RenderPlatformWindowsDefault();
+            }
+
             [renderEncoder popDebugGroup];
             [renderEncoder endEncoding];
 

diff --git a/examples/example_glfw_opengl2/main.cpp b/examples/example_glfw_opengl2/main.cpp
index 48584ea..24bc843 100644
--- a/examples/example_glfw_opengl2/main.cpp
+++ b/examples/example_glfw_opengl2/main.cpp

@@ -53,6 +53,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -62,6 +66,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplGlfw_InitForOpenGL(window, true);
@@ -163,6 +176,17 @@
         ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());
         //glUseProgram(last_program);
 
+        // Update and Render additional Platform Windows
+        // (Platform functions may change the current OpenGL context, so we save/restore it to make it easier to paste this code elsewhere.
+        //  For this specific demo app we could also call glfwMakeContextCurrent(window) directly)
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            GLFWwindow* backup_current_context = glfwGetCurrentContext();
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+            glfwMakeContextCurrent(backup_current_context);
+        }
+
         glfwMakeContextCurrent(window);
         glfwSwapBuffers(window);
     }

diff --git a/examples/example_glfw_opengl3/main.cpp b/examples/example_glfw_opengl3/main.cpp
index 20d39fc..e487fe7 100644
--- a/examples/example_glfw_opengl3/main.cpp
+++ b/examples/example_glfw_opengl3/main.cpp

@@ -84,6 +84,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -93,6 +97,17 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+#if GLFW_VERSION_MAJOR >= 3 && GLFW_VERSION_MINOR >= 3
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+#endif
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplGlfw_InitForOpenGL(window, true);
@@ -198,6 +213,17 @@
         glClear(GL_COLOR_BUFFER_BIT);
         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
 
+        // Update and Render additional Platform Windows
+        // (Platform functions may change the current OpenGL context, so we save/restore it to make it easier to paste this code elsewhere.
+        //  For this specific demo app we could also call glfwMakeContextCurrent(window) directly)
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            GLFWwindow* backup_current_context = glfwGetCurrentContext();
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+            glfwMakeContextCurrent(backup_current_context);
+        }
+
         glfwSwapBuffers(window);
     }
 #ifdef __EMSCRIPTEN__

diff --git a/examples/example_glfw_vulkan/main.cpp b/examples/example_glfw_vulkan/main.cpp
index d70c7ce..5b25ef9 100644
--- a/examples/example_glfw_vulkan/main.cpp
+++ b/examples/example_glfw_vulkan/main.cpp

@@ -389,6 +389,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -398,6 +402,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplGlfw_InitForVulkan(window, true);
@@ -512,17 +525,25 @@
 
         // Rendering
         ImGui::Render();
-        ImDrawData* draw_data = ImGui::GetDrawData();
-        const bool is_minimized = (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f);
-        if (!is_minimized)
+        ImDrawData* main_draw_data = ImGui::GetDrawData();
+        const bool main_is_minimized = (main_draw_data->DisplaySize.x <= 0.0f || main_draw_data->DisplaySize.y <= 0.0f);
+        wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
+        wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
+        wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
+        wd->ClearValue.color.float32[3] = clear_color.w;
+        if (!main_is_minimized)
+            FrameRender(wd, main_draw_data);
+
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
         {
-            wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
-            wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
-            wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
-            wd->ClearValue.color.float32[3] = clear_color.w;
-            FrameRender(wd, draw_data);
-            FramePresent(wd);
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
         }
+
+        // Present Main Platform Window
+        if (!main_is_minimized)
+            FramePresent(wd);
     }
 
     // Cleanup

diff --git a/examples/example_glfw_wgpu/main.cpp b/examples/example_glfw_wgpu/main.cpp
index 1a6373c..d41988c 100644
--- a/examples/example_glfw_wgpu/main.cpp
+++ b/examples/example_glfw_wgpu/main.cpp

@@ -90,6 +90,7 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();

diff --git a/examples/example_glut_opengl2/main.cpp b/examples/example_glut_opengl2/main.cpp
index ca8017f..8ee9616 100644
--- a/examples/example_glut_opengl2/main.cpp
+++ b/examples/example_glut_opengl2/main.cpp

@@ -61,6 +61,7 @@
     ImGui::CreateContext();
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();

diff --git a/examples/example_sdl2_directx11/main.cpp b/examples/example_sdl2_directx11/main.cpp
index cf39716..56de728 100644
--- a/examples/example_sdl2_directx11/main.cpp
+++ b/examples/example_sdl2_directx11/main.cpp

@@ -75,6 +75,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -84,6 +88,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplSDL2_InitForD3D(window);
@@ -192,6 +205,13 @@
         g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
         ImGui_ImplDX11_RenderDrawData(ImGui::GetDrawData());
 
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+        }
+
         g_pSwapChain->Present(1, 0); // Present with vsync
         //g_pSwapChain->Present(0, 0); // Present without vsync
     }
@@ -239,6 +259,16 @@
     if (res != S_OK)
         return false;
 
+    // Disable DXGI's default Alt+Enter fullscreen behavior.
+    // - You are free to leave this enabled, but it will not work properly with multiple viewports.
+    // - This must be done for all windows associated to the device. Our DX11 backend does this automatically for secondary viewports that it creates.
+    IDXGIFactory* pSwapChainFactory;
+    if (SUCCEEDED(g_pSwapChain->GetParent(IID_PPV_ARGS(&pSwapChainFactory))))
+    {
+        pSwapChainFactory->MakeWindowAssociation(hWnd, DXGI_MWA_NO_ALT_ENTER);
+        pSwapChainFactory->Release();
+    }
+
     CreateRenderTarget();
     return true;
 }

diff --git a/examples/example_sdl2_metal/main.mm b/examples/example_sdl2_metal/main.mm
index ea2afda..e559154 100644
--- a/examples/example_sdl2_metal/main.mm
+++ b/examples/example_sdl2_metal/main.mm

@@ -24,11 +24,21 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;  // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;   // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;      // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;    // Enable Multi-Viewport / Platform Windows
 
     // Setup style
     ImGui::StyleColorsDark();
     //ImGui::StyleColorsLight();
 
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    ImGuiStyle& style = ImGui::GetStyle();
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
+
     // Load Fonts
     // - If fonts are not explicitly loaded, Dear ImGui will select an embedded font: either AddFontDefaultVector() or AddFontDefaultBitmap().
     //   This selection is based on (style.FontSizeBase * style.FontScaleMain * style.FontScaleDpi) reaching a small threshold.
@@ -170,6 +180,13 @@
             ImGui::Render();
             ImGui_ImplMetal_RenderDrawData(ImGui::GetDrawData(), commandBuffer, renderEncoder);
 
+            // Update and Render additional Platform Windows
+            if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+            {
+                ImGui::UpdatePlatformWindows();
+                ImGui::RenderPlatformWindowsDefault();
+            }
+
             [renderEncoder popDebugGroup];
             [renderEncoder endEncoding];
 

diff --git a/examples/example_sdl2_opengl2/main.cpp b/examples/example_sdl2_opengl2/main.cpp
index 3b3412b..b1de045 100644
--- a/examples/example_sdl2_opengl2/main.cpp
+++ b/examples/example_sdl2_opengl2/main.cpp

@@ -64,6 +64,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -73,6 +77,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
@@ -174,6 +187,19 @@
         glClear(GL_COLOR_BUFFER_BIT);
         //glUseProgram(0); // You may want this if using this code in an OpenGL 3+ context where shaders may be bound
         ImGui_ImplOpenGL2_RenderDrawData(ImGui::GetDrawData());
+
+        // Update and Render additional Platform Windows
+        // (Platform functions may change the current OpenGL context, so we save/restore it to make it easier to paste this code elsewhere.
+        //  For this specific demo app we could also call SDL_GL_MakeCurrent(window, gl_context) directly)
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            SDL_Window* backup_current_window = SDL_GL_GetCurrentWindow();
+            SDL_GLContext backup_current_context = SDL_GL_GetCurrentContext();
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+            SDL_GL_MakeCurrent(backup_current_window, backup_current_context);
+        }
+
         SDL_GL_SwapWindow(window);
     }
 

diff --git a/examples/example_sdl2_opengl3/main.cpp b/examples/example_sdl2_opengl3/main.cpp
index 0d992d4..1c51e59 100644
--- a/examples/example_sdl2_opengl3/main.cpp
+++ b/examples/example_sdl2_opengl3/main.cpp

@@ -104,6 +104,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -113,6 +117,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplSDL2_InitForOpenGL(window, gl_context);
@@ -221,6 +234,19 @@
         glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
         glClear(GL_COLOR_BUFFER_BIT);
         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
+
+        // Update and Render additional Platform Windows
+        // (Platform functions may change the current OpenGL context, so we save/restore it to make it easier to paste this code elsewhere.
+        //  For this specific demo app we could also call SDL_GL_MakeCurrent(window, gl_context) directly)
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            SDL_Window* backup_current_window = SDL_GL_GetCurrentWindow();
+            SDL_GLContext backup_current_context = SDL_GL_GetCurrentContext();
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+            SDL_GL_MakeCurrent(backup_current_window, backup_current_context);
+        }
+
         SDL_GL_SwapWindow(window);
     }
 #ifdef __EMSCRIPTEN__

diff --git a/examples/example_sdl2_sdlrenderer2/main.cpp b/examples/example_sdl2_sdlrenderer2/main.cpp
index b698673..ee3ab8f 100644
--- a/examples/example_sdl2_sdlrenderer2/main.cpp
+++ b/examples/example_sdl2_sdlrenderer2/main.cpp

@@ -66,6 +66,7 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -75,6 +76,8 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
 
     // Setup Platform/Renderer backends
     ImGui_ImplSDL2_InitForSDLRenderer(window, renderer);

diff --git a/examples/example_sdl2_vulkan/main.cpp b/examples/example_sdl2_vulkan/main.cpp
index f395343..c8c2ae4 100644
--- a/examples/example_sdl2_vulkan/main.cpp
+++ b/examples/example_sdl2_vulkan/main.cpp

@@ -395,6 +395,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoTaskBarIcons;
+    //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoMerge;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -404,6 +408,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplSDL2_InitForVulkan(window);
@@ -527,17 +540,25 @@
 
         // Rendering
         ImGui::Render();
-        ImDrawData* draw_data = ImGui::GetDrawData();
-        const bool is_minimized = (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f);
-        if (!is_minimized)
+        ImDrawData* main_draw_data = ImGui::GetDrawData();
+        const bool main_is_minimized = (main_draw_data->DisplaySize.x <= 0.0f || main_draw_data->DisplaySize.y <= 0.0f);
+        wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
+        wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
+        wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
+        wd->ClearValue.color.float32[3] = clear_color.w;
+        if (!main_is_minimized)
+            FrameRender(wd, main_draw_data);
+
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
         {
-            wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
-            wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
-            wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
-            wd->ClearValue.color.float32[3] = clear_color.w;
-            FrameRender(wd, draw_data);
-            FramePresent(wd);
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
         }
+
+        // Present Main Platform Window
+        if (!main_is_minimized)
+            FramePresent(wd);
     }
 
     // Cleanup

diff --git a/examples/example_sdl3_directx11/main.cpp b/examples/example_sdl3_directx11/main.cpp
index 4337d4e..db6d6e8 100644
--- a/examples/example_sdl3_directx11/main.cpp
+++ b/examples/example_sdl3_directx11/main.cpp

@@ -66,6 +66,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -75,6 +79,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplSDL3_InitForD3D(window);
@@ -186,6 +199,13 @@
         g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
         ImGui_ImplDX11_RenderDrawData(ImGui::GetDrawData());
 
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+        }
+
         g_pSwapChain->Present(1, 0); // Present with vsync
         //g_pSwapChain->Present(0, 0); // Present without vsync
     }
@@ -234,6 +254,16 @@
     if (res != S_OK)
         return false;
 
+    // Disable DXGI's default Alt+Enter fullscreen behavior.
+    // - You are free to leave this enabled, but it will not work properly with multiple viewports.
+    // - This must be done for all windows associated to the device. Our DX11 backend does this automatically for secondary viewports that it creates.
+    IDXGIFactory* pSwapChainFactory;
+    if (SUCCEEDED(g_pSwapChain->GetParent(IID_PPV_ARGS(&pSwapChainFactory))))
+    {
+        pSwapChainFactory->MakeWindowAssociation(hWnd, DXGI_MWA_NO_ALT_ENTER);
+        pSwapChainFactory->Release();
+    }
+
     CreateRenderTarget();
     return true;
 }

diff --git a/examples/example_sdl3_opengl3/main.cpp b/examples/example_sdl3_opengl3/main.cpp
index a36cfab..07f0cd0 100644
--- a/examples/example_sdl3_opengl3/main.cpp
+++ b/examples/example_sdl3_opengl3/main.cpp

@@ -94,6 +94,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -103,6 +107,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplSDL3_InitForOpenGL(window, gl_context);
@@ -214,6 +227,19 @@
         glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
         glClear(GL_COLOR_BUFFER_BIT);
         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
+
+        // Update and Render additional Platform Windows
+        // (Platform functions may change the current OpenGL context, so we save/restore it to make it easier to paste this code elsewhere.
+        //  For this specific demo app we could also call SDL_GL_MakeCurrent(window, gl_context) directly)
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            SDL_Window* backup_current_window = SDL_GL_GetCurrentWindow();
+            SDL_GLContext backup_current_context = SDL_GL_GetCurrentContext();
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+            SDL_GL_MakeCurrent(backup_current_window, backup_current_context);
+        }
+
         SDL_GL_SwapWindow(window);
     }
 #ifdef __EMSCRIPTEN__

diff --git a/examples/example_sdl3_sdlgpu3/main.cpp b/examples/example_sdl3_sdlgpu3/main.cpp
index 8edbbbb..ede905a 100644
--- a/examples/example_sdl3_sdlgpu3/main.cpp
+++ b/examples/example_sdl3_sdlgpu3/main.cpp

@@ -68,6 +68,8 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -77,6 +79,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplSDL3_InitForSDLGPU(window);
@@ -212,6 +223,13 @@
             SDL_EndGPURenderPass(render_pass);
         }
 
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+        }
+
         // Submit the command buffer
         SDL_SubmitGPUCommandBuffer(command_buffer);
     }

diff --git a/examples/example_sdl3_sdlrenderer3/main.cpp b/examples/example_sdl3_sdlrenderer3/main.cpp
index 88f9ac7..c9b5551 100644
--- a/examples/example_sdl3_sdlrenderer3/main.cpp
+++ b/examples/example_sdl3_sdlrenderer3/main.cpp

@@ -56,6 +56,7 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -65,6 +66,8 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    //io.ConfigDpiScaleFonts = true;        // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    //io.ConfigDpiScaleViewports = true;    // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
 
     // Setup Platform/Renderer backends
     ImGui_ImplSDL3_InitForSDLRenderer(window, renderer);

diff --git a/examples/example_sdl3_vulkan/main.cpp b/examples/example_sdl3_vulkan/main.cpp
index f461aab..bae033d 100644
--- a/examples/example_sdl3_vulkan/main.cpp
+++ b/examples/example_sdl3_vulkan/main.cpp

@@ -394,6 +394,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoTaskBarIcons;
+    //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoMerge;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -403,6 +407,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplSDL3_InitForVulkan(window);
@@ -529,17 +542,25 @@
 
         // Rendering
         ImGui::Render();
-        ImDrawData* draw_data = ImGui::GetDrawData();
-        const bool is_minimized = (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f);
-        if (!is_minimized)
+        ImDrawData* main_draw_data = ImGui::GetDrawData();
+        const bool main_is_minimized = (main_draw_data->DisplaySize.x <= 0.0f || main_draw_data->DisplaySize.y <= 0.0f);
+        wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
+        wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
+        wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
+        wd->ClearValue.color.float32[3] = clear_color.w;
+        if (!main_is_minimized)
+            FrameRender(wd, main_draw_data);
+
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
         {
-            wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
-            wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
-            wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
-            wd->ClearValue.color.float32[3] = clear_color.w;
-            FrameRender(wd, draw_data);
-            FramePresent(wd);
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
         }
+
+        // Present Main Platform Window
+        if (!main_is_minimized)
+            FramePresent(wd);
     }
 
     // Cleanup

diff --git a/examples/example_win32_directx10/main.cpp b/examples/example_win32_directx10/main.cpp
index 2c34207..f367300 100644
--- a/examples/example_win32_directx10/main.cpp
+++ b/examples/example_win32_directx10/main.cpp

@@ -57,6 +57,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -66,6 +70,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplWin32_Init(hwnd);
@@ -177,6 +190,13 @@
         g_pd3dDevice->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
         ImGui_ImplDX10_RenderDrawData(ImGui::GetDrawData());
 
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+        }
+
         // Present
         HRESULT hr = g_pSwapChain->Present(1, 0);   // Present with vsync
         //HRESULT hr = g_pSwapChain->Present(0, 0); // Present without vsync
@@ -196,7 +216,6 @@
 }
 
 // Helper functions
-
 bool CreateDeviceD3D(HWND hWnd)
 {
     // Setup swap chain
@@ -225,6 +244,16 @@
     if (res != S_OK)
         return false;
 
+    // Disable DXGI's default Alt+Enter fullscreen behavior.
+    // - You are free to leave this enabled, but it will not work properly with multiple viewports.
+    // - This must be done for all windows associated to the device. Our DX11 backend does this automatically for secondary viewports that it creates.
+    IDXGIFactory* pSwapChainFactory;
+    if (SUCCEEDED(g_pSwapChain->GetParent(IID_PPV_ARGS(&pSwapChainFactory))))
+    {
+        pSwapChainFactory->MakeWindowAssociation(hWnd, DXGI_MWA_NO_ALT_ENTER);
+        pSwapChainFactory->Release();
+    }
+
     CreateRenderTarget();
     return true;
 }

diff --git a/examples/example_win32_directx11/main.cpp b/examples/example_win32_directx11/main.cpp
index 524538a..8580569 100644
--- a/examples/example_win32_directx11/main.cpp
+++ b/examples/example_win32_directx11/main.cpp

@@ -57,6 +57,12 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
+    //io.ConfigDockingAlwaysTabBar = true;
+    //io.ConfigDockingTransparentPayload = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -66,6 +72,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplWin32_Init(hwnd);
@@ -177,6 +192,13 @@
         g_pd3dDeviceContext->ClearRenderTargetView(g_mainRenderTargetView, clear_color_with_alpha);
         ImGui_ImplDX11_RenderDrawData(ImGui::GetDrawData());
 
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+        }
+
         // Present
         HRESULT hr = g_pSwapChain->Present(1, 0);   // Present with vsync
         //HRESULT hr = g_pSwapChain->Present(0, 0); // Present without vsync
@@ -196,7 +218,6 @@
 }
 
 // Helper functions
-
 bool CreateDeviceD3D(HWND hWnd)
 {
     // Setup swap chain
@@ -227,6 +248,16 @@
     if (res != S_OK)
         return false;
 
+    // Disable DXGI's default Alt+Enter fullscreen behavior.
+    // - You are free to leave this enabled, but it will not work properly with multiple viewports.
+    // - This must be done for all windows associated to the device. Our DX11 backend does this automatically for secondary viewports that it creates.
+    IDXGIFactory* pSwapChainFactory;
+    if (SUCCEEDED(g_pSwapChain->GetParent(IID_PPV_ARGS(&pSwapChainFactory))))
+    {
+        pSwapChainFactory->MakeWindowAssociation(hWnd, DXGI_MWA_NO_ALT_ENTER);
+        pSwapChainFactory->Release();
+    }
+
     CreateRenderTarget();
     return true;
 }

diff --git a/examples/example_win32_directx12/main.cpp b/examples/example_win32_directx12/main.cpp
index 0d8bb20..b199ffa 100644
--- a/examples/example_win32_directx12/main.cpp
+++ b/examples/example_win32_directx12/main.cpp

@@ -137,6 +137,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -146,6 +150,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplWin32_Init(hwnd);
@@ -285,6 +298,14 @@
         g_pd3dCommandList->Close();
 
         g_pd3dCommandQueue->ExecuteCommandLists(1, (ID3D12CommandList* const*)&g_pd3dCommandList);
+
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+        }
+
         g_pd3dCommandQueue->Signal(g_fence, ++g_fenceLastSignaledValue);
         frameCtx->FenceValue = g_fenceLastSignaledValue;
 
@@ -310,7 +331,6 @@
 }
 
 // Helper functions
-
 bool CreateDeviceD3D(HWND hWnd)
 {
     // Setup swap chain

diff --git a/examples/example_win32_directx9/main.cpp b/examples/example_win32_directx9/main.cpp
index fbe4c39..3dff6b4 100644
--- a/examples/example_win32_directx9/main.cpp
+++ b/examples/example_win32_directx9/main.cpp

@@ -55,6 +55,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigViewportsNoAutoMerge = true;
+    //io.ConfigViewportsNoTaskBarIcon = true;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -64,6 +68,15 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplWin32_Init(hwnd);
@@ -187,6 +200,14 @@
             ImGui_ImplDX9_RenderDrawData(ImGui::GetDrawData());
             g_pd3dDevice->EndScene();
         }
+
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+        }
+
         HRESULT result = g_pd3dDevice->Present(nullptr, nullptr, nullptr, nullptr);
         if (result == D3DERR_DEVICELOST)
             g_DeviceLost = true;
@@ -205,7 +226,6 @@
 }
 
 // Helper functions
-
 bool CreateDeviceD3D(HWND hWnd)
 {
     if ((g_pD3D = Direct3DCreate9(D3D_SDK_VERSION)) == nullptr)

diff --git a/examples/example_win32_opengl3/main.cpp b/examples/example_win32_opengl3/main.cpp
index d18ea0b..ee77ee2 100644
--- a/examples/example_win32_opengl3/main.cpp
+++ b/examples/example_win32_opengl3/main.cpp

@@ -33,6 +33,42 @@
 void ResetDeviceWGL();
 LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
 
+// Support function for multi-viewports
+// Unlike most other backend combination, we need specific hooks to combine Win32+OpenGL.
+// We could in theory decide to support Win32-specific code in OpenGL backend via e.g. an hypothetical ImGui_ImplOpenGL3_InitForRawWin32().
+static void Hook_Renderer_CreateWindow(ImGuiViewport* viewport)
+{
+    assert(viewport->RendererUserData == NULL);
+
+    WGL_WindowData* data = IM_NEW(WGL_WindowData);
+    CreateDeviceWGL((HWND)viewport->PlatformHandle, data);
+    viewport->RendererUserData = data;
+}
+
+static void Hook_Renderer_DestroyWindow(ImGuiViewport* viewport)
+{
+    if (viewport->RendererUserData != NULL)
+    {
+        WGL_WindowData* data = (WGL_WindowData*)viewport->RendererUserData;
+        CleanupDeviceWGL((HWND)viewport->PlatformHandle, data);
+        IM_DELETE(data);
+        viewport->RendererUserData = NULL;
+    }
+}
+
+static void Hook_Platform_RenderWindow(ImGuiViewport* viewport, void*)
+{
+    // Activate the platform window DC in the OpenGL rendering context
+    if (WGL_WindowData* data = (WGL_WindowData*)viewport->RendererUserData)
+        wglMakeCurrent(data->hDC, g_hRC);
+}
+
+static void Hook_Renderer_SwapBuffers(ImGuiViewport* viewport, void*)
+{
+    if (WGL_WindowData* data = (WGL_WindowData*)viewport->RendererUserData)
+        ::SwapBuffers(data->hDC);
+}
+
 // Main code
 int main(int, char**)
 {
@@ -65,6 +101,8 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;   // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;    // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;       // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;     // Enable Multi-Viewport / Platform Windows
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -74,11 +112,34 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplWin32_InitForOpenGL(hwnd);
     ImGui_ImplOpenGL3_Init();
 
+    // Win32+GL needs specific hooks for viewport, as there are specific things needed to tie Win32 and GL api.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+        IM_ASSERT(platform_io.Renderer_CreateWindow == NULL);
+        IM_ASSERT(platform_io.Renderer_DestroyWindow == NULL);
+        IM_ASSERT(platform_io.Renderer_SwapBuffers == NULL);
+        IM_ASSERT(platform_io.Platform_RenderWindow == NULL);
+        platform_io.Renderer_CreateWindow = Hook_Renderer_CreateWindow;
+        platform_io.Renderer_DestroyWindow = Hook_Renderer_DestroyWindow;
+        platform_io.Renderer_SwapBuffers = Hook_Renderer_SwapBuffers;
+        platform_io.Platform_RenderWindow = Hook_Platform_RenderWindow;
+    }
+
     // Load Fonts
     // - If fonts are not explicitly loaded, Dear ImGui will select an embedded font: either AddFontDefaultVector() or AddFontDefaultBitmap().
     //   This selection is based on (style.FontSizeBase * style.FontScaleMain * style.FontScaleDpi) reaching a small threshold.
@@ -173,6 +234,16 @@
         glClear(GL_COLOR_BUFFER_BIT);
         ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
 
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+        {
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
+
+            // Restore the OpenGL rendering context to the main window DC, since platform windows might have changed it.
+            wglMakeCurrent(g_MainWindow.hDC, g_hRC);
+        }
+
         // Present
         ::SwapBuffers(g_MainWindow.hDC);
     }

diff --git a/examples/example_win32_vulkan/main.cpp b/examples/example_win32_vulkan/main.cpp
index 7f1ccd0..eaaa67e 100644
--- a/examples/example_win32_vulkan/main.cpp
+++ b/examples/example_win32_vulkan/main.cpp

@@ -339,6 +339,16 @@
 
 LRESULT WINAPI WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
 
+// FIXME: This code would ideally be inside imgui_impl_win32.cpp, it would create a dependency on Vulkan headers in imgui_impl_win32.cpp
+static int ImGui_ImplWin32_CreateVkSurface(ImGuiViewport* viewport, ImU64 vk_instance, const void* vk_allocator, ImU64* out_vk_surface)
+{
+    VkWin32SurfaceCreateInfoKHR createInfo = {};
+    createInfo.sType = VK_STRUCTURE_TYPE_WIN32_SURFACE_CREATE_INFO_KHR;
+    createInfo.hwnd = (HWND)viewport->PlatformHandleRaw;
+    createInfo.hinstance = ::GetModuleHandle(nullptr);
+    return (int)vkCreateWin32SurfaceKHR((VkInstance)vk_instance, &createInfo, (VkAllocationCallbacks*)vk_allocator, (VkSurfaceKHR*)out_vk_surface);
+}
+
 // Main code
 int main(int, char**)
 {
@@ -382,6 +392,10 @@
     ImGuiIO& io = ImGui::GetIO(); (void)io;
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;     // Enable Keyboard Controls
     io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad;      // Enable Gamepad Controls
+    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;         // Enable Docking
+    io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable;       // Enable Multi-Viewport / Platform Windows
+    //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoTaskBarIcons;
+    //io.ConfigFlags |= ImGuiConfigFlags_ViewportsNoMerge;
 
     // Setup Dear ImGui style
     ImGui::StyleColorsDark();
@@ -391,9 +405,20 @@
     ImGuiStyle& style = ImGui::GetStyle();
     style.ScaleAllSizes(main_scale);        // Bake a fixed style scale. (until we have a solution for dynamic style scaling, changing this requires resetting Style + calling this again)
     style.FontScaleDpi = main_scale;        // Set initial font scale. (in docking branch: using io.ConfigDpiScaleFonts=true automatically overrides this for every window depending on the current monitor)
+    io.ConfigDpiScaleFonts = true;          // [Experimental] Automatically overwrite style.FontScaleDpi in Begin() when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    io.ConfigDpiScaleViewports = true;      // [Experimental] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
+    // When viewports are enabled we tweak WindowRounding/WindowBg so platform windows can look identical to regular ones.
+    if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        style.WindowRounding = 0.0f;
+        style.Colors[ImGuiCol_WindowBg].w = 1.0f;
+    }
 
     // Setup Platform/Renderer backends
     ImGui_ImplWin32_Init(hwnd);
+    ImGui::GetPlatformIO().Platform_CreateVkSurface = ImGui_ImplWin32_CreateVkSurface;
+
     ImGui_ImplVulkan_InitInfo init_info = {};
     //init_info.ApiVersion = VK_API_VERSION_1_3;              // Pass in your value of VkApplicationInfo::apiVersion, otherwise will default to header version.
     init_info.Instance = g_Instance;
@@ -496,17 +521,25 @@
 
         // Rendering
         ImGui::Render();
-        ImDrawData* draw_data = ImGui::GetDrawData();
-        const bool is_minimized = (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f);
-        if (!is_minimized)
+        ImDrawData* main_draw_data = ImGui::GetDrawData();
+        const bool main_is_minimized = (main_draw_data->DisplaySize.x <= 0.0f || main_draw_data->DisplaySize.y <= 0.0f);
+        wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
+        wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
+        wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
+        wd->ClearValue.color.float32[3] = clear_color.w;
+        if (!main_is_minimized)
+            FrameRender(wd, main_draw_data);
+
+        // Update and Render additional Platform Windows
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
         {
-            wd->ClearValue.color.float32[0] = clear_color.x * clear_color.w;
-            wd->ClearValue.color.float32[1] = clear_color.y * clear_color.w;
-            wd->ClearValue.color.float32[2] = clear_color.z * clear_color.w;
-            wd->ClearValue.color.float32[3] = clear_color.w;
-            FrameRender(wd, draw_data);
-            FramePresent(wd);
+            ImGui::UpdatePlatformWindows();
+            ImGui::RenderPlatformWindowsDefault();
         }
+
+        // Present Main Platform Window
+        if (!main_is_minimized)
+            FramePresent(wd);
     }
 
     // Cleanup

diff --git a/imgui.cpp b/imgui.cpp
index 93cff90..5567f1d 100644
--- a/imgui.cpp
+++ b/imgui.cpp

@@ -95,6 +95,7 @@
 // [SECTION] SETTINGS
 // [SECTION] LOCALIZATION
 // [SECTION] VIEWPORTS, PLATFORM WINDOWS
+// [SECTION] DOCKING
 // [SECTION] PLATFORM DEPENDENT HELPERS
 // [SECTION] METRICS/DEBUGGER WINDOW
 // [SECTION] DEBUG LOG WINDOW
@@ -394,6 +395,13 @@
  When you are not sure about an old symbol or function name, try using the Search/Find function of your IDE to look for comments or references in all imgui files.
  You can read releases logs https://github.com/ocornut/imgui/releases for more details.
 
+(Docking/Viewport Branch)
+ - 2026/XX/XX (1.XXXX) - when multi-viewports are enabled, all positions will be in your natural OS coordinates space. It means that:
+                          - reference to hard-coded positions such as in SetNextWindowPos(ImVec2(0,0)) are probably not what you want anymore.
+                            you may use GetMainViewport()->Pos to offset hard-coded positions, e.g. SetNextWindowPos(GetMainViewport()->Pos)
+                          - likewise io.MousePos and GetMousePos() will use OS coordinates.
+                            If you query mouse positions to interact with non-imgui coordinates you will need to offset them, e.g. subtract GetWindowViewport()->Pos.
+
  - 2026/01/08 (1.92.6) - Commented out legacy names obsoleted in 1.90 (Sept 2023): 'BeginChildFrame()' --> 'BeginChild()' with 'ImGuiChildFlags_FrameStyle'. 'EndChildFrame()' --> 'EndChild()'. 'ShowStackToolWindow()' --> 'ShowIDStackToolWindow()'. 'IM_OFFSETOF()' --> 'offsetof()'.
  - 2026/01/07 (1.92.6) - Popups: changed compile-time 'ImGuiPopupFlags popup_flags = 1' default value to be '= 0' for BeginPopupContextItem(), BeginPopupContextWindow(), BeginPopupContextVoid(), OpenPopupOnItemClick(). Default value has same meaning before and after.
                          - Refer to GitHub topic #9157 if you have any question.
@@ -444,6 +452,7 @@
                          - ImGuiTreeNodeFlags_AllowItemOverlap       --> ImGuiTreeNodeFlags_AllowOverlap
                          - ImGuiSelectableFlags_AllowItemOverlap     --> ImGuiSelectableFlags_AllowOverlap
                          - ImGuiListClipper::IncludeRangeByIndices() --> ImGuiListClipper::IncludeItemsByIndex()
+ - 2025/09/22 (1.92.4) - Viewports: renamed io.ConfigViewportPlatformFocusSetsImGuiFocus to io.ConfigViewportsPlatformFocusSetsImGuiFocus. Was a typo in the first place. (#6299, #6462)
  - 2025/08/08 (1.92.2) - Backends: SDL_GPU3: Changed ImTextureID type from SDL_GPUTextureSamplerBinding* to SDL_GPUTexture*, which is more natural and easier for user to manage. If you need to change the current sampler, you can access the ImGui_ImplSDLGPU3_RenderState struct. (#8866, #8163, #7998, #7988)
  - 2025/07/31 (1.92.2) - Tabs: Renamed ImGuiTabBarFlags_FittingPolicyResizeDown to ImGuiTabBarFlags_FittingPolicyShrink. Kept inline redirection enum (will obsolete).
  - 2025/06/25 (1.92.0) - Layout: commented out legacy ErrorCheckUsingSetCursorPosToExtendParentBoundaries() fallback obsoleted in 1.89 (August 2022) which allowed a SetCursorPos()/SetCursorScreenPos() call WITHOUT AN ITEM
@@ -454,6 +463,9 @@
                               Begin(...) + SetCursorScreenPos(GetCursorScreenPos() + ImVec2(200,200)) + Dummy(ImVec2(0,0)) + End();
                               Begin(...) + Dummy(ImVec2(200,200)) + End();
                          - TL;DR; if the assert triggers, you can add a Dummy({0,0}) call to validate extending parent boundaries.
+ - 2025/06/11 (1.92.0) - Renamed/moved ImGuiConfigFlags_DpiEnableScaleFonts -> bool io.ConfigDpiScaleFonts.
+                       - Renamed/moved ImGuiConfigFlags_DpiEnableScaleViewports -> bool io.ConfigDpiScaleViewports. **Neither of those flags are very useful in current code. They will be useful once we merge font changes.**
+                         [there was a bug on 2025/06/12: when using the old config flags names, they were not imported correctly into the new ones, fixed on 2025/09/12]
  - 2025/06/11 (1.92.0) - THIS VERSION CONTAINS THE LARGEST AMOUNT OF BREAKING CHANGES SINCE 2015! I TRIED REALLY HARD TO KEEP THEM TO A MINIMUM, REDUCE THE AMOUNT OF INTERFERENCES, BUT INEVITABLY SOME USERS WILL BE AFFECTED.
                          IN ORDER TO HELP US IMPROVE THE TRANSITION PROCESS, INCL. DOCUMENTATION AND COMMENTS, PLEASE REPORT **ANY** DOUBT, CONFUSION, QUESTIONS, FEEDBACK TO: https://github.com/ocornut/imgui/issues/
                          As part of the plan to reduce impact of API breaking changes, several unfinished changes/features/refactors related to font and text systems and scaling will be part of subsequent releases (1.92.1+).
@@ -645,6 +657,9 @@
                             - new: IsMouseClicked(ImGuiMouseButton button, ImGuiInputFlags flags, ImGuiID owner_id = 0);
                          for various reasons those changes makes sense. They are being made because making some of those API public.
                          only past users of imgui_internal.h with the extra parameters will be affected. Added asserts for valid flags in various functions to detect _some_ misuses, BUT NOT ALL.
+ - 2024/05/21 (1.90.7) - docking: changed signature of DockSpaceOverViewport() to add explicit dockspace id if desired. pass 0 to use old behavior. (#7611)
+                           - old: DockSpaceOverViewport(const ImGuiViewport* viewport = NULL, ImGuiDockNodeFlags flags = 0, ...);
+                           - new: DockSpaceOverViewport(ImGuiID dockspace_id = 0, const ImGuiViewport* viewport = NULL, ImGuiDockNodeFlags flags = 0, ...);
  - 2024/05/16 (1.90.7) - inputs: on macOS X, Cmd and Ctrl keys are now automatically swapped by io.AddKeyEvent() as this naturally align with how macOS X uses those keys.
                            - it shouldn't really affect you unless you had custom shortcut swapping in place for macOS X apps.
                            - removed ImGuiMod_Shortcut which was previously dynamically remapping to Ctrl or Cmd/Super. It is now unnecessary to specific cross-platform idiomatic shortcuts. (#2343, #4084, #5923, #456)
@@ -1302,6 +1317,9 @@
 static const ImVec2 TOOLTIP_DEFAULT_OFFSET_TOUCH = ImVec2(0, -20);      // Multiplied by g.Style.MouseCursorScale
 static const ImVec2 TOOLTIP_DEFAULT_PIVOT_TOUCH = ImVec2(0.5f, 1.0f);   // Multiplied by g.Style.MouseCursorScale
 
+// Docking
+static const float DOCKING_TRANSPARENT_PAYLOAD_ALPHA        = 0.50f;    // For use with io.ConfigDockingTransparentPayload. Apply to Viewport _or_ WindowBg in host viewport.
+
 //-------------------------------------------------------------------------
 // [SECTION] FORWARD DECLARATIONS
 //-------------------------------------------------------------------------
@@ -1388,7 +1406,18 @@
 
 // Viewports
 const ImGuiID           IMGUI_VIEWPORT_DEFAULT_ID = 0x11111111; // Using an arbitrary constant instead of e.g. ImHashStr("ViewportDefault", 0); so it's easier to spot in the debugger. The exact value doesn't matter.
+static ImGuiViewportP*  AddUpdateViewport(ImGuiWindow* window, ImGuiID id, const ImVec2& platform_pos, const ImVec2& size, ImGuiViewportFlags flags);
+static void             DestroyViewport(ImGuiViewportP* viewport);
 static void             UpdateViewportsNewFrame();
+static void             UpdateViewportsEndFrame();
+static void             WindowSelectViewport(ImGuiWindow* window);
+static void             WindowSyncOwnedViewport(ImGuiWindow* window, ImGuiWindow* parent_window_in_stack);
+static bool             UpdateTryMergeWindowIntoHostViewport(ImGuiWindow* window, ImGuiViewportP* host_viewport);
+static bool             UpdateTryMergeWindowIntoHostViewports(ImGuiWindow* window);
+static bool             GetWindowAlwaysWantOwnViewport(ImGuiWindow* window);
+static int              FindPlatformMonitorForPos(const ImVec2& pos);
+static int              FindPlatformMonitorForRect(const ImRect& r);
+static void             UpdateViewportPlatformMonitor(ImGuiViewportP* viewport);
 
 }
 
@@ -1499,6 +1528,8 @@
     SeparatorTextPadding        = ImVec2(20.0f,3.f);// Horizontal offset of text from each edge of the separator + spacing on other axis. Generally small values. .y is recommended to be == FramePadding.y.
     DisplayWindowPadding        = ImVec2(19,19);    // Window position are clamped to be visible within the display area or monitors by at least this amount. Only applies to regular windows.
     DisplaySafeAreaPadding      = ImVec2(3,3);      // If you cannot see the edge of your screen (e.g. on a TV) increase the safe area padding. Covers popups/tooltips as well regular windows.
+    DockingNodeHasCloseButton   = true;             // Docking nodes have their own CloseButton() to close all docked windows.
+    DockingSeparatorSize        = 2.0f;             // Thickness of resizing border between docked windows
     MouseCursorScale            = 1.0f;             // Scale software rendered mouse cursor (when io.MouseDrawCursor is enabled). May be removed later.
     AntiAliasedLines            = true;             // Enable anti-aliased lines/borders. Disable if you are really tight on CPU/GPU.
     AntiAliasedLinesUseTex      = true;             // Enable anti-aliased lines/borders using textures where possible. Require backend to render with bilinear filtering (NOT point/nearest filtering).
@@ -1561,6 +1592,7 @@
     DragDropTargetPadding = ImTrunc(DragDropTargetPadding * scale_factor);
     ColorMarkerSize = ImTrunc(ColorMarkerSize * scale_factor);
     SeparatorTextPadding = ImTrunc(SeparatorTextPadding * scale_factor);
+    DockingSeparatorSize = ImTrunc(DockingSeparatorSize * scale_factor);
     DisplayWindowPadding = ImTrunc(DisplayWindowPadding * scale_factor);
     DisplaySafeAreaPadding = ImTrunc(DisplaySafeAreaPadding * scale_factor);
     MouseCursorScale = ImTrunc(MouseCursorScale * scale_factor);
@@ -1599,6 +1631,20 @@
     ConfigNavCursorVisibleAuto = true;
     ConfigNavCursorVisibleAlways = false;
 
+    // Docking options (when ImGuiConfigFlags_DockingEnable is set)
+    ConfigDockingNoSplit = false;
+    ConfigDockingNoDockingOver = false;
+    ConfigDockingWithShift = false;
+    ConfigDockingAlwaysTabBar = false;
+    ConfigDockingTransparentPayload = false;
+
+    // Viewport options (when ImGuiConfigFlags_ViewportsEnable is set)
+    ConfigViewportsNoAutoMerge = false;
+    ConfigViewportsNoTaskBarIcon = false;
+    ConfigViewportsNoDecoration = true;
+    ConfigViewportsNoDefaultParent = true;
+    ConfigViewportsPlatformFocusSetsImGuiFocus = true;
+
     // Miscellaneous options
     MouseDrawCursor = false;
 #ifdef __APPLE__
@@ -1954,6 +2000,27 @@
     g.InputEventsNextMouseSource = source;
 }
 
+void ImGuiIO::AddMouseViewportEvent(ImGuiID viewport_id)
+{
+    IM_ASSERT(Ctx != NULL);
+    ImGuiContext& g = *Ctx;
+    //IM_ASSERT(g.IO.BackendFlags & ImGuiBackendFlags_HasMouseHoveredViewport);
+    if (!AppAcceptingEvents)
+        return;
+
+    // Filter duplicate
+    const ImGuiInputEvent* latest_event = FindLatestInputEvent(&g, ImGuiInputEventType_MouseViewport);
+    const ImGuiID latest_viewport_id = latest_event ? latest_event->MouseViewport.HoveredViewportID : g.IO.MouseHoveredViewport;
+    if (latest_viewport_id == viewport_id)
+        return;
+
+    ImGuiInputEvent e;
+    e.Type = ImGuiInputEventType_MouseViewport;
+    e.Source = ImGuiInputSource_Mouse;
+    e.MouseViewport.HoveredViewportID = viewport_id;
+    g.InputEventsQueue.push_back(e);
+}
+
 void ImGuiIO::AddFocusEvent(bool focused)
 {
     IM_ASSERT(Ctx != NULL);
@@ -3583,6 +3650,11 @@
     }
 }
 
+static const ImGuiCol GWindowDockStyleColors[ImGuiWindowDockStyleCol_COUNT] =
+{
+    ImGuiCol_Text, ImGuiCol_TabHovered, ImGuiCol_Tab, ImGuiCol_TabSelected, ImGuiCol_TabSelectedOverline, ImGuiCol_TabDimmed, ImGuiCol_TabDimmedSelected, ImGuiCol_TabDimmedSelectedOverline, ImGuiCol_UnsavedMarker,
+};
+
 static const ImGuiStyleVarInfo GStyleVarsInfo[] =
 {
     { 1, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, Alpha) },                     // ImGuiStyleVar_Alpha
@@ -3625,6 +3697,7 @@
     { 1, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, SeparatorTextBorderSize)},    // ImGuiStyleVar_SeparatorTextBorderSize
     { 2, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, SeparatorTextAlign) },        // ImGuiStyleVar_SeparatorTextAlign
     { 2, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, SeparatorTextPadding) },      // ImGuiStyleVar_SeparatorTextPadding
+    { 1, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, DockingSeparatorSize) },      // ImGuiStyleVar_DockingSeparatorSize
 };
 
 const ImGuiStyleVarInfo* ImGui::GetStyleVarInfo(ImGuiStyleVar idx)
@@ -3741,6 +3814,8 @@
     case ImGuiCol_TabDimmed: return "TabDimmed";
     case ImGuiCol_TabDimmedSelected: return "TabDimmedSelected";
     case ImGuiCol_TabDimmedSelectedOverline: return "TabDimmedSelectedOverline";
+    case ImGuiCol_DockingPreview: return "DockingPreview";
+    case ImGuiCol_DockingEmptyBg: return "DockingEmptyBg";
     case ImGuiCol_PlotLines: return "PlotLines";
     case ImGuiCol_PlotLinesHovered: return "PlotLinesHovered";
     case ImGuiCol_PlotHistogram: return "PlotHistogram";
@@ -4008,7 +4083,7 @@
         if (!ImFontAtlasGetMouseCursorTexData(font_atlas, mouse_cursor, &offset, &size, &uv[0], &uv[2]))
             continue;
         const ImVec2 pos = base_pos - offset;
-        const float scale = base_scale;
+        const float scale = base_scale * viewport->DpiScale;
         if (!viewport->GetMainRect().Overlaps(ImRect(pos, pos + ImVec2(size.x + 2, size.y + 2) * scale)))
             continue;
         ImDrawList* draw_list = GetForegroundDrawList(viewport);
@@ -4099,6 +4174,9 @@
     { ImGuiLocKey_WindowingUntitled,    "(Untitled)"                            },
     { ImGuiLocKey_OpenLink_s,           "Open '%s'"                             },
     { ImGuiLocKey_CopyLink,             "Copy Link###CopyLink"                  },
+    { ImGuiLocKey_DockingHideTabBar,            "Hide tab bar###HideTabBar"             },
+    { ImGuiLocKey_DockingHoldShiftToDock,       "Hold SHIFT to enable Docking window."  },
+    { ImGuiLocKey_DockingDragToUndockOrMoveNode,"Click and drag to move or undock whole node."    },
 };
 
 ImGuiContext::ImGuiContext(ImFontAtlas* shared_font_atlas)
@@ -4110,9 +4188,10 @@
     WithinFrameScope = WithinFrameScopeWithImplicitWindow = false;
     TestEngineHookItems = false;
     FrameCount = 0;
-    FrameCountEnded = FrameCountRendered = -1;
+    FrameCountEnded = FrameCountPlatformEnded = FrameCountRendered = -1;
     Time = 0.0f;
     memset(ContextName, 0, sizeof(ContextName));
+    ConfigFlagsCurrFrame = ConfigFlagsLastFrame = ImGuiConfigFlags_None;
 
     Font = NULL;
     FontBaked = NULL;
@@ -4177,6 +4256,12 @@
     DebugShowGroupRects = false;
     GcCompactAll = false;
 
+    CurrentViewport = NULL;
+    MouseViewport = MouseLastHoveredViewport = NULL;
+    PlatformLastFocusedViewportId = 0;
+    ViewportCreatedCount = PlatformWindowsCreatedCount = 0;
+    ViewportFocusedStampCount = 0;
+
     NavCursorVisible = false;
     NavHighlightItemUnderNav = false;
     NavMousePosDirty = false;
@@ -4278,6 +4363,8 @@
     PlatformImeData.InputPos = ImVec2(0.0f, 0.0f);
     PlatformImeDataPrev.InputPos = ImVec2(-1.0f, -1.0f); // Different to ensure initial submission
 
+    DockNodeWindowMenuHandler = NULL;
+
     SettingsLoaded = false;
     SettingsDirtyTimer = 0.0f;
     HookIdNext = 0;
@@ -4313,6 +4400,7 @@
     DebugItemPickerBreakId = 0;
     DebugFlashStyleColorTime = 0.0f;
     DebugFlashStyleColorIdx = ImGuiCol_COUNT;
+    DebugHoveredDockNode = NULL;
 
     // Same as DebugBreakClearData(). Those fields are scattered in their respective subsystem to stay in hot-data locations
     DebugBreakInWindow = 0;
@@ -4364,8 +4452,13 @@
     // Create default viewport
     ImGuiViewportP* viewport = IM_NEW(ImGuiViewportP)();
     viewport->ID = IMGUI_VIEWPORT_DEFAULT_ID;
+    viewport->Idx = 0;
+    viewport->PlatformWindowCreated = true;
+    viewport->Flags = ImGuiViewportFlags_OwnedByApp;
     g.Viewports.push_back(viewport);
     g.TempBuffer.resize(1024 * 3 + 1, 0);
+    g.ViewportCreatedCount++;
+    g.PlatformIO.Viewports.push_back(g.Viewports[0]);
 
     // Build KeysMayBeCharInput[] lookup table (1 bit per named key)
     for (ImGuiKey key = ImGuiKey_NamedKey_BEGIN; key < ImGuiKey_NamedKey_END; key = (ImGuiKey)(key + 1))
@@ -4376,6 +4469,8 @@
             g.KeysMayBeCharInput.SetBit(key);
 
 #ifdef IMGUI_HAS_DOCK
+    // Initialize Docking
+    DockContextInitialize(&g);
 #endif
 
     // Print a debug message when running with debug feature IMGUI_DEBUG_HIGHLIGHT_ALL_ID_CONFLICTS because it is very slow.
@@ -4399,6 +4494,11 @@
     ImGuiContext& g = *GImGui;
     IM_ASSERT_USER_ERROR(g.IO.BackendPlatformUserData == NULL, "Forgot to shutdown Platform backend?");
     IM_ASSERT_USER_ERROR(g.IO.BackendRendererUserData == NULL, "Forgot to shutdown Renderer backend?");
+    for (ImGuiViewportP* viewport : g.Viewports)
+    {
+        IM_UNUSED(viewport);
+        IM_ASSERT_USER_ERROR(viewport->RendererUserData == NULL && viewport->PlatformUserData == NULL && viewport->PlatformHandle == NULL, "Backend or app forgot to call DestroyPlatformWindows()?");
+    }
 
     // The fonts atlas can be used prior to calling NewFrame(), so we clear it even if g.Initialized is FALSE (which would happen if we never called NewFrame)
     for (ImFontAtlas* atlas : g.FontAtlases)
@@ -4420,6 +4520,9 @@
     if (g.SettingsLoaded && g.IO.IniFilename != NULL)
         SaveIniSettingsToDisk(g.IO.IniFilename);
 
+    // Shutdown extensions
+    DockContextShutdown(&g);
+
     CallContextHooks(&g, ImGuiContextHookType_Shutdown);
 
     // Clear everything else
@@ -4443,6 +4546,7 @@
     g.BeginPopupStack.clear();
     g.TreeNodeStack.clear();
 
+    g.CurrentViewport = g.MouseViewport = g.MouseLastHoveredViewport = NULL;
     g.Viewports.clear_delete();
 
     g.TabBars.Clear();
@@ -4532,22 +4636,28 @@
     NameBufLen = (int)ImStrlen(name) + 1;
     ID = ImHashStr(name);
     IDStack.push_back(ID);
+    ViewportAllowPlatformMonitorExtend = -1;
+    ViewportPos = ImVec2(FLT_MAX, FLT_MAX);
     MoveId = GetID("#MOVE");
+    TabId = GetID("#TAB");
     ScrollTarget = ImVec2(FLT_MAX, FLT_MAX);
     ScrollTargetCenterRatio = ImVec2(0.5f, 0.5f);
     AutoPosLastDirection = ImGuiDir_None;
     AutoFitFramesX = AutoFitFramesY = -1;
-    SetWindowPosAllowFlags = SetWindowSizeAllowFlags = SetWindowCollapsedAllowFlags = 0;
+    SetWindowPosAllowFlags = SetWindowSizeAllowFlags = SetWindowCollapsedAllowFlags = SetWindowDockAllowFlags = 0;
     SetWindowPosVal = SetWindowPosPivot = ImVec2(FLT_MAX, FLT_MAX);
     LastFrameActive = -1;
+    LastFrameJustFocused = -1;
     LastTimeActive = -1.0f;
     FontRefSize = 0.0f;
     FontWindowScale = FontWindowScaleParents = 1.0f;
     SettingsOffset = -1;
+    DockOrder = -1;
     DrawList = &DrawListInst;
     DrawList->_OwnerName = Name;
     DrawList->_SetDrawListSharedData(&Ctx->DrawListSharedData);
     NavPreferredScoringPosRel[0] = NavPreferredScoringPosRel[1] = ImVec2(FLT_MAX, FLT_MAX);
+    IM_PLACEMENT_NEW(&WindowClass) ImGuiWindowClass();
 }
 
 ImGuiWindow::~ImGuiWindow()
@@ -4563,7 +4673,6 @@
     g.CurrentWindow = window;
     g.StackSizesInBeginForCurrentWindow = g.CurrentWindow ? &g.CurrentWindowStack.back().StackSizesInBegin : NULL;
     g.CurrentTable = window && window->DC.CurrentTableIdx != -1 ? g.Tables.GetByIndex(window->DC.CurrentTableIdx) : NULL;
-    g.CurrentDpiScale = 1.0f; // FIXME-DPI: WIP this is modified in docking
     if (window)
     {
         if (g.IO.BackendFlags & ImGuiBackendFlags_RendererHasTextures)
@@ -4734,8 +4843,8 @@
     // FIXME-OPT: This could be cached/stored within the window.
     ImGuiContext& g = *GImGui;
     if (g.NavWindow)
-        if (ImGuiWindow* focused_root_window = g.NavWindow->RootWindow)
-            if (focused_root_window->WasActive && focused_root_window != window->RootWindow)
+        if (ImGuiWindow* focused_root_window = g.NavWindow->RootWindowDockTree)
+            if (focused_root_window->WasActive && focused_root_window != window->RootWindowDockTree)
             {
                 // For the purpose of those flags we differentiate "standard popup" from "modal popup"
                 // NB: The 'else' is important because Modal windows are also Popups.
@@ -4750,6 +4859,12 @@
                     if (!IsWindowWithinBeginStackOf(window->RootWindow, focused_root_window))
                         return false;
             }
+
+    // Filter by viewport
+    if (window->Viewport != g.MouseViewport)
+        if (g.MovingWindow == NULL || window->RootWindowDockTree != g.MovingWindow->RootWindowDockTree)
+            return false;
+
     return true;
 }
 
@@ -4822,6 +4937,9 @@
                 bool cancel_is_hovered = true;
                 if (g.ActiveId == window->MoveId && (id == 0 || g.ActiveIdDisabledId == id))
                     cancel_is_hovered = false;
+                // When ActiveId == TabId it means user clicked docking tab for the window.
+                if (g.ActiveId == window->TabId)
+                    cancel_is_hovered = false;
                 if (cancel_is_hovered)
                     return false;
             }
@@ -4995,7 +5113,10 @@
 static void ImGui::SetLastItemDataForWindow(ImGuiWindow* window, const ImRect& rect)
 {
     ImGuiContext& g = *GImGui;
-    SetLastItemData(window->MoveId, g.CurrentItemFlags, window->DC.WindowItemStatusFlags, rect);
+    if (window->DockIsActive)
+        SetLastItemData(window->MoveId, g.CurrentItemFlags, window->DC.DockTabItemStatusFlags, window->DC.DockTabItemRect);
+    else
+        SetLastItemData(window->MoveId, g.CurrentItemFlags, window->DC.WindowItemStatusFlags, rect);
 }
 
 static void ImGui::SetLastItemDataForChildWindowItem(ImGuiWindow* window, const ImRect& rect)
@@ -5165,26 +5286,18 @@
 
 ImDrawList* ImGui::GetBackgroundDrawList(ImGuiViewport* viewport)
 {
+    if (viewport == NULL)
+        viewport = GImGui->CurrentWindow->Viewport;
     return GetViewportBgFgDrawList((ImGuiViewportP*)viewport, 0, "##Background");
 }
 
-ImDrawList* ImGui::GetBackgroundDrawList()
-{
-    ImGuiContext& g = *GImGui;
-    return GetBackgroundDrawList(g.Viewports[0]);
-}
-
 ImDrawList* ImGui::GetForegroundDrawList(ImGuiViewport* viewport)
 {
+    if (viewport == NULL)
+        viewport = GImGui->CurrentWindow->Viewport;
     return GetViewportBgFgDrawList((ImGuiViewportP*)viewport, 1, "##Foreground");
 }
 
-ImDrawList* ImGui::GetForegroundDrawList()
-{
-    ImGuiContext& g = *GImGui;
-    return GetForegroundDrawList(g.Viewports[0]);
-}
-
 ImDrawListSharedData* ImGui::GetDrawListSharedData()
 {
     return &GImGui->DrawListSharedData;
@@ -5200,17 +5313,43 @@
     SetActiveID(window->MoveId, window);
     if (g.IO.ConfigNavCursorVisibleAuto)
         g.NavCursorVisible = false;
-    g.ActiveIdClickOffset = g.IO.MouseClickedPos[0] - window->RootWindow->Pos;
+    g.ActiveIdClickOffset = g.IO.MouseClickedPos[0] - window->RootWindowDockTree->Pos;
     g.ActiveIdNoClearOnFocusLoss = true;
     SetActiveIdUsingAllKeyboardKeys();
 
     bool can_move_window = true;
-    if ((window->Flags & ImGuiWindowFlags_NoMove) || (window->RootWindow->Flags & ImGuiWindowFlags_NoMove))
+    if ((window->Flags & ImGuiWindowFlags_NoMove) || (window->RootWindowDockTree->Flags & ImGuiWindowFlags_NoMove))
         can_move_window = false;
+    if (ImGuiDockNode* node = window->DockNodeAsHost)
+        if (node->VisibleWindow && (node->VisibleWindow->Flags & ImGuiWindowFlags_NoMove))
+            can_move_window = false;
     if (can_move_window)
         g.MovingWindow = window;
 }
 
+// We use 'undock == false' when dragging from title bar to allow moving groups of floating nodes without undocking them.
+void ImGui::StartMouseMovingWindowOrNode(ImGuiWindow* window, ImGuiDockNode* node, bool undock)
+{
+    ImGuiContext& g = *GImGui;
+    bool can_undock_node = false;
+    if (undock && node != NULL && node->VisibleWindow && (node->VisibleWindow->Flags & ImGuiWindowFlags_NoMove) == 0 && (node->MergedFlags & ImGuiDockNodeFlags_NoUndocking) == 0)
+    {
+        // Can undock if:
+        // - part of a hierarchy with more than one visible node (if only one is visible, we'll just move the root window)
+        // - part of a dockspace node hierarchy: so we can undock the last single visible node too. Undocking from a fixed/central node will create a new node and copy windows.
+        ImGuiDockNode* root_node = DockNodeGetRootNode(node);
+        if (root_node->OnlyNodeWithWindows != node || root_node->CentralNode != NULL)   // -V1051 PVS-Studio thinks node should be root_node and is wrong about that.
+            can_undock_node = true;
+    }
+
+    const bool clicked = IsMouseClicked(0);
+    const bool dragging = IsMouseDragging(0);
+    if (can_undock_node && dragging)
+        DockContextQueueUndockNode(&g, node); // Will lead to DockNodeStartMouseMovingWindow() -> StartMouseMovingWindow() being called next frame
+    else if (!can_undock_node && (clicked || dragging) && g.MovingWindow != window)
+        StartMouseMovingWindow(window);
+}
+
 // This is not 100% symmetric with StartMouseMovingWindow().
 // We do NOT clear ActiveID, because:
 // - It would lead to rather confusing recursive code paths. Caller can call ClearActiveID() if desired.
@@ -5218,9 +5357,25 @@
 void ImGui::StopMouseMovingWindow()
 {
     ImGuiContext& g = *GImGui;
+    ImGuiWindow* window = g.MovingWindow;
 
-    // [nb: docking branch has more stuff in this function]
+    // Ref commits 6b7766817, 36055213c for some partial history on checking if viewport != NULL.
+    if (window && window->Viewport)
+    {
+        // Try to merge the window back into the main viewport.
+        // This works because MouseViewport should be != MovingWindow->Viewport on release (as per code in UpdateViewports)
+        if (g.ConfigFlagsCurrFrame & ImGuiConfigFlags_ViewportsEnable)
+            UpdateTryMergeWindowIntoHostViewport(window->RootWindowDockTree, g.MouseViewport);
 
+        // Restore the mouse viewport so that we don't hover the viewport _under_ the moved window during the frame we released the mouse button.
+        if (!IsDragDropPayloadBeingAccepted())
+            g.MouseViewport = window->Viewport;
+
+        // Clear the NoInputs window flag set by the Viewport system in AddUpdateViewport()
+        const bool window_can_use_inputs = ((window->Flags & ImGuiWindowFlags_NoMouseInputs) && (window->Flags & ImGuiWindowFlags_NoNavInputs)) == false;
+        if (window_can_use_inputs)
+            window->Viewport->Flags &= ~ImGuiViewportFlags_NoInputs;
+    }
     g.MovingWindow = NULL;
 }
 
@@ -5237,12 +5392,23 @@
         // We actually want to move the root window. g.MovingWindow == window we clicked on (could be a child window).
         // We track it to preserve Focus and so that generally ActiveIdWindow == MovingWindow and ActiveId == MovingWindow->MoveId for consistency.
         KeepAliveID(g.ActiveId);
-        IM_ASSERT(g.MovingWindow && g.MovingWindow->RootWindow);
-        ImGuiWindow* moving_window = g.MovingWindow->RootWindow;
-        if (g.IO.MouseDown[0] && IsMousePosValid(&g.IO.MousePos))
+        IM_ASSERT(g.MovingWindow && g.MovingWindow->RootWindowDockTree);
+        ImGuiWindow* moving_window = g.MovingWindow->RootWindowDockTree;
+
+        // When a window stop being submitted while being dragged, it may will its viewport until next Begin()
+        const bool window_disappeared = (!moving_window->WasActive && !moving_window->Active);
+        if (g.IO.MouseDown[0] && IsMousePosValid(&g.IO.MousePos) && !window_disappeared)
         {
             ImVec2 pos = g.IO.MousePos - g.ActiveIdClickOffset;
-            SetWindowPos(moving_window, pos, ImGuiCond_Always);
+            if (moving_window->Pos.x != pos.x || moving_window->Pos.y != pos.y)
+            {
+                SetWindowPos(moving_window, pos, ImGuiCond_Always);
+                if (moving_window->Viewport && moving_window->ViewportOwned) // Synchronize viewport immediately because some overlays may relies on clipping rectangle before we Begin() into the window.
+                {
+                    moving_window->Viewport->Pos = pos;
+                    moving_window->Viewport->UpdateWorkRect();
+                }
+            }
             FocusWindow(g.MovingWindow);
         }
         else
@@ -5279,7 +5445,7 @@
     ImGuiWindow* hovered_window = g.HoveredWindow;
 
     // Click on empty space to focus window and start moving
-    // (after we're done with all our widgets)
+    // (after we're done with all our widgets, so e.g. clicking on docking tab-bar which have set HoveredId already and not get us here!)
     if (g.IO.MouseClicked[0])
     {
         // Handle the edge case of a popup being closed while clicking in its empty space.
@@ -5296,7 +5462,7 @@
 
             // Cancel moving if clicked outside of title bar
             if ((hovered_window->BgClickFlags & ImGuiWindowBgClickFlags_Move) == 0) // set by io.ConfigWindowsMoveFromTitleBarOnly
-                if (!(hovered_root->Flags & ImGuiWindowFlags_NoTitleBar))
+                if (!(hovered_root->Flags & ImGuiWindowFlags_NoTitleBar) || hovered_root->DockIsActive)
                     if (!hovered_root->TitleBarRect().Contains(g.IO.MouseClickedPos[0]))
                         g.MovingWindow = NULL;
 
@@ -5328,6 +5494,29 @@
     }
 }
 
+// This is called during NewFrame()->UpdateViewportsNewFrame() only.
+// Need to keep in sync with SetWindowPos()
+static void TranslateWindow(ImGuiWindow* window, const ImVec2& delta)
+{
+    window->Pos += delta;
+    window->ClipRect.Translate(delta);
+    window->OuterRectClipped.Translate(delta);
+    window->InnerRect.Translate(delta);
+    window->DC.CursorPos += delta;
+    window->DC.CursorStartPos += delta;
+    window->DC.CursorMaxPos += delta;
+    window->DC.IdealMaxPos += delta;
+}
+
+static void ScaleWindow(ImGuiWindow* window, float scale)
+{
+    ImVec2 origin = window->Viewport->Pos;
+    window->Pos = ImFloor((window->Pos - origin) * scale + origin);
+    window->Size = ImTrunc(window->Size * scale);
+    window->SizeFull = ImTrunc(window->SizeFull * scale);
+    window->ContentSize = ImTrunc(window->ContentSize * scale);
+}
+
 static bool IsWindowActiveAndVisible(ImGuiWindow* window)
 {
     return window->Active && !window->Hidden;
@@ -5349,11 +5538,12 @@
     // - We also support the moved window toggling the NoInputs flag after moving has started in order to be able to detect windows below it, which is useful for e.g. docking mechanisms.
     bool clear_hovered_windows = false;
     FindHoveredWindowEx(mouse_pos, false, &g.HoveredWindow, &g.HoveredWindowUnderMovingWindow);
+    IM_ASSERT(g.HoveredWindow == NULL || g.HoveredWindow == g.MovingWindow || g.HoveredWindow->Viewport == g.MouseViewport);
     g.HoveredWindowBeforeClear = g.HoveredWindow;
 
     // Modal windows prevents mouse from hovering behind them.
     ImGuiWindow* modal_window = GetTopMostPopupModal();
-    if (modal_window && g.HoveredWindow && !IsWindowWithinBeginStackOf(g.HoveredWindow->RootWindow, modal_window))
+    if (modal_window && g.HoveredWindow && !IsWindowWithinBeginStackOf(g.HoveredWindow->RootWindow, modal_window)) // FIXME-MERGE: RootWindowDockTree ?
         clear_hovered_windows = true;
 
     // Disabled mouse hovering (we don't currently clear MousePos, we could)
@@ -5455,7 +5645,9 @@
     CallContextHooks(&g, ImGuiContextHookType_NewFramePre);
 
     // Check and assert for various common IO and Configuration mistakes
+    g.ConfigFlagsLastFrame = g.ConfigFlagsCurrFrame;
     ErrorCheckNewFrameSanityChecks();
+    g.ConfigFlagsCurrFrame = g.IO.ConfigFlags;
 
     // Load settings on first frame, save settings when modified (after a delay)
     UpdateSettings();
@@ -5491,7 +5683,10 @@
 
     // Mark rendering data as invalid to prevent user who may have a handle on it to use it.
     for (ImGuiViewportP* viewport : g.Viewports)
+    {
+        viewport->DrawData = NULL;
         viewport->DrawDataP.Valid = false;
+    }
 
     // Drag and drop keep the source ID alive so even if the source disappear our state is consistent
     if (g.DragDropActive && g.DragDropPayload.SourceId == g.ActiveId)
@@ -5617,6 +5812,10 @@
     // Update mouse input state
     UpdateMouseInputs();
 
+    // Undocking
+    // (needs to be before UpdateMouseMovingWindowNewFrame so the window is already offset and following the mouse on the detaching frame)
+    DockContextNewFrameUpdateUndocking(&g);
+
     // Mark all windows as not visible and compact unused memory.
     IM_ASSERT(g.WindowsFocusOrder.Size <= g.Windows.Size);
     const float memory_compact_start_time = (g.GcCompactAll || g.IO.ConfigMemoryCompactTimer < 0.0f) ? FLT_MAX : (float)g.Time - g.IO.ConfigMemoryCompactTimer;
@@ -5681,6 +5880,9 @@
     g.CurrentItemFlags = g.ItemFlagsStack.back();
     g.GroupStack.resize(0);
 
+    // Docking
+    DockContextNewFrameUpdateDocking(&g);
+
     // [DEBUG] Update debug features
 #ifndef IMGUI_DISABLE_DEBUG_TOOLS
     UpdateDebugToolItemPicker();
@@ -5754,7 +5956,8 @@
 static void AddWindowToDrawData(ImGuiWindow* window, int layer)
 {
     ImGuiContext& g = *GImGui;
-    ImGuiViewportP* viewport = g.Viewports[0];
+    ImGuiViewportP* viewport = window->Viewport;
+    IM_ASSERT(viewport != NULL);
     g.IO.MetricsRenderWindows++;
     if (window->DrawList->_Splitter._Count > 1)
         window->DrawList->ChannelsMerge(); // Merge if user forgot to merge back. Also required in Docking branch for ImGuiWindowFlags_DockNodeHost windows.
@@ -5798,17 +6001,25 @@
     ImGuiIO& io = ImGui::GetIO();
     ImDrawData* draw_data = &viewport->DrawDataP;
 
+    viewport->DrawData = draw_data; // Make publicly accessible
     viewport->DrawDataBuilder.Layers[0] = &draw_data->CmdLists;
     viewport->DrawDataBuilder.Layers[1] = &viewport->DrawDataBuilder.LayerData1;
     viewport->DrawDataBuilder.Layers[0]->resize(0);
     viewport->DrawDataBuilder.Layers[1]->resize(0);
 
+    // When minimized, we report draw_data->DisplaySize as zero to be consistent with non-viewport mode,
+    // and to allow applications/backends to easily skip rendering.
+    // FIXME: Note that we however do NOT attempt to report "zero drawlist / vertices" into the ImDrawData structure.
+    // This is because the work has been done already, and its wasted! We should fix that and add optimizations for
+    // it earlier in the pipeline, rather than pretend to hide the data at the end of the pipeline.
+    const bool is_minimized = (viewport->Flags & ImGuiViewportFlags_IsMinimized) != 0;
+
     draw_data->Valid = true;
     draw_data->CmdListsCount = 0;
     draw_data->TotalVtxCount = draw_data->TotalIdxCount = 0;
     draw_data->DisplayPos = viewport->Pos;
-    draw_data->DisplaySize = viewport->Size;
-    draw_data->FramebufferScale = io.DisplayFramebufferScale;
+    draw_data->DisplaySize = is_minimized ? ImVec2(0.0f, 0.0f) : viewport->Size;
+    draw_data->FramebufferScale = (viewport->FramebufferScale.x != 0.0f) ? viewport->FramebufferScale : io.DisplayFramebufferScale;
     draw_data->OwnerViewport = viewport;
     draw_data->Textures = &ImGui::GetPlatformIO().Textures;
 }
@@ -5835,31 +6046,52 @@
     window->ClipRect = window->DrawList->_ClipRectStack.back();
 }
 
+static ImGuiWindow* FindFrontMostVisibleChildWindow(ImGuiWindow* window)
+{
+    for (int n = window->DC.ChildWindows.Size - 1; n >= 0; n--)
+        if (IsWindowActiveAndVisible(window->DC.ChildWindows[n]))
+            return FindFrontMostVisibleChildWindow(window->DC.ChildWindows[n]);
+    return window;
+}
+
 static void ImGui::RenderDimmedBackgroundBehindWindow(ImGuiWindow* window, ImU32 col)
 {
     if ((col & IM_COL32_A_MASK) == 0)
         return;
 
-    ImGuiViewportP* viewport = (ImGuiViewportP*)GetMainViewport();
+    ImGuiViewportP* viewport = window->Viewport;
     ImRect viewport_rect = viewport->GetMainRect();
 
     // Draw behind window by moving the draw command at the FRONT of the draw list
     {
-        // We've already called AddWindowToDrawData() which called DrawList->ChannelsMerge() on DockNodeHost windows,
-        // and draw list have been trimmed already, hence the explicit recreation of a draw command if missing.
-        // FIXME: This is creating complication, might be simpler if we could inject a drawlist in drawdata at a given position and not attempt to manipulate ImDrawCmd order.
-        ImDrawList* draw_list = window->RootWindow->DrawList;
+        // Draw list have been trimmed already, hence the explicit recreation of a draw command if missing.
+        // FIXME: This is a little bit complicated, solely to avoid creating/injecting an extra drawlist in drawdata.
+        ImDrawList* draw_list = window->RootWindowDockTree->DrawList;
+        draw_list->ChannelsMerge();
         if (draw_list->CmdBuffer.Size == 0)
             draw_list->AddDrawCmd();
         draw_list->PushClipRect(viewport_rect.Min - ImVec2(1, 1), viewport_rect.Max + ImVec2(1, 1), false); // FIXME: Need to stricty ensure ImDrawCmd are not merged (ElemCount==6 checks below will verify that)
-        draw_list->AddRectFilled(viewport_rect.Min, viewport_rect.Max, col);
         ImDrawCmd cmd = draw_list->CmdBuffer.back();
-        IM_ASSERT(cmd.ElemCount == 6);
+        IM_ASSERT(cmd.ElemCount == 0);
+        draw_list->AddRectFilled(viewport_rect.Min, viewport_rect.Max, col);
+        cmd = draw_list->CmdBuffer.back();
         draw_list->CmdBuffer.pop_back();
         draw_list->CmdBuffer.push_front(cmd);
         draw_list->AddDrawCmd(); // We need to create a command as CmdBuffer.back().IdxOffset won't be correct if we append to same command.
         draw_list->PopClipRect();
     }
+
+    // Draw over sibling docking nodes in a same docking tree
+    if (window->RootWindow->DockIsActive)
+    {
+        ImDrawList* draw_list = FindFrontMostVisibleChildWindow(window->RootWindowDockTree)->DrawList;
+        draw_list->ChannelsMerge();
+        if (draw_list->CmdBuffer.Size == 0)
+            draw_list->AddDrawCmd();
+        draw_list->PushClipRect(viewport_rect.Min, viewport_rect.Max, false);
+        RenderRectFilledWithHole(draw_list, window->RootWindowDockTree->Rect(), window->RootWindow->Rect(), col, 0.0f);// window->RootWindowDockTree->WindowRounding);
+        draw_list->PopClipRect();
+    }
 }
 
 ImGuiWindow* ImGui::FindBottomMostVisibleWindowWithinBeginStack(ImGuiWindow* parent_window)
@@ -5879,6 +6111,8 @@
     return bottom_most_visible_window;
 }
 
+// Important: AddWindowToDrawData() has not been called yet, meaning DockNodeHost windows needs a DrawList->ChannelsMerge() before usage.
+// We call ChannelsMerge() lazily here at it is faster that doing a full iteration of g.Windows[] prior to calling RenderDimmedBackgrounds().
 static void ImGui::RenderDimmedBackgrounds()
 {
     ImGuiContext& g = *GImGui;
@@ -5890,31 +6124,52 @@
     if (!dim_bg_for_modal && !dim_bg_for_window_list)
         return;
 
+    ImGuiViewport* viewports_already_dimmed[2] = { NULL, NULL };
     if (dim_bg_for_modal)
     {
         // Draw dimming behind modal or a begin stack child, whichever comes first in draw order.
         ImGuiWindow* dim_behind_window = FindBottomMostVisibleWindowWithinBeginStack(modal_window);
         RenderDimmedBackgroundBehindWindow(dim_behind_window, GetColorU32(modal_window->DC.ModalDimBgColor, g.DimBgRatio));
+        viewports_already_dimmed[0] = modal_window->Viewport;
     }
     else if (dim_bg_for_window_list)
     {
         // Draw dimming behind Ctrl+Tab target window and behind Ctrl+Tab UI window
         RenderDimmedBackgroundBehindWindow(g.NavWindowingTargetAnim, GetColorU32(ImGuiCol_NavWindowingDimBg, g.DimBgRatio));
+        viewports_already_dimmed[0] = g.NavWindowingTargetAnim->Viewport;
+        if (g.NavWindowingListWindow != NULL && g.NavWindowingListWindow->Active && g.NavWindowingListWindow->Viewport && g.NavWindowingListWindow->Viewport != g.NavWindowingTargetAnim->Viewport)
+        {
+            RenderDimmedBackgroundBehindWindow(g.NavWindowingListWindow, GetColorU32(ImGuiCol_NavWindowingDimBg, g.DimBgRatio));
+            viewports_already_dimmed[1] = g.NavWindowingListWindow->Viewport;
+        }
 
         // Draw border around Ctrl+Tab target window
         ImGuiWindow* window = g.NavWindowingTargetAnim;
-        ImGuiViewport* viewport = GetMainViewport();
+        ImGuiViewport* viewport = window->Viewport;
         float distance = g.FontSize;
         ImRect bb = window->Rect();
         bb.Expand(distance);
         if (bb.GetWidth() >= viewport->Size.x && bb.GetHeight() >= viewport->Size.y)
             bb.Expand(-distance - 1.0f); // If a window fits the entire viewport, adjust its highlight inward
+        window->DrawList->ChannelsMerge();
         if (window->DrawList->CmdBuffer.Size == 0)
             window->DrawList->AddDrawCmd();
         window->DrawList->PushClipRect(viewport->Pos, viewport->Pos + viewport->Size);
         window->DrawList->AddRect(bb.Min, bb.Max, GetColorU32(ImGuiCol_NavWindowingHighlight, g.NavWindowingHighlightAlpha), window->WindowRounding, 0, 3.0f); // FIXME-DPI
         window->DrawList->PopClipRect();
     }
+
+    // Draw dimming background on _other_ viewports than the ones our windows are in
+    for (ImGuiViewportP* viewport : g.Viewports)
+    {
+        if (viewport == viewports_already_dimmed[0] || viewport == viewports_already_dimmed[1])
+            continue;
+        if (modal_window && viewport->Window && IsWindowAbove(viewport->Window, modal_window))
+            continue;
+        ImDrawList* draw_list = GetForegroundDrawList(viewport);
+        const ImU32 dim_bg_col = GetColorU32(dim_bg_for_modal ? ImGuiCol_ModalWindowDimBg : ImGuiCol_NavWindowingDimBg, g.DimBgRatio);
+        draw_list->AddRectFilled(viewport->Pos, viewport->Pos + viewport->Size, dim_bg_col);
+    }
 }
 
 // This is normally called by Render(). You may want to call it directly if you want to avoid calling Render() but the gain will be very minimal.
@@ -5940,8 +6195,9 @@
     ImGuiPlatformImeData* ime_data = &g.PlatformImeData;
     if (g.PlatformIO.Platform_SetImeDataFn != NULL && memcmp(ime_data, &g.PlatformImeDataPrev, sizeof(ImGuiPlatformImeData)) != 0)
     {
-        IM_ASSERT(ime_data->ViewportId == IMGUI_VIEWPORT_DEFAULT_ID); // master branch
-        ImGuiViewport* viewport = GetMainViewport();
+        ImGuiViewport* viewport = FindViewportByID(ime_data->ViewportId);
+        if (viewport == NULL)
+            viewport = GetMainViewport();
         IMGUI_DEBUG_LOG_IO("[io] Calling Platform_SetImeDataFn(): WantVisible: %d, InputPos (%.2f,%.2f) for Viewport 0x%08X\n", ime_data->WantVisible, ime_data->InputPos.x, ime_data->InputPos.y, viewport->ID);
         g.PlatformIO.Platform_SetImeDataFn(&g, viewport, ime_data);
     }
@@ -5949,13 +6205,18 @@
 
     // Hide implicit/fallback "Debug" window if it hasn't been used
     g.WithinFrameScopeWithImplicitWindow = false;
-    if (g.CurrentWindow && !g.CurrentWindow->WriteAccessed)
+    if (g.CurrentWindow && g.CurrentWindow->IsFallbackWindow && g.CurrentWindow->WriteAccessed == false)
         g.CurrentWindow->Active = false;
     End();
 
     // Update navigation: Ctrl+Tab, wrap-around requests
     NavEndFrame();
 
+    // Update docking
+    DockContextEndFrame(&g);
+
+    SetCurrentViewport(NULL, NULL);
+
     // Drag and Drop: Elapse payload (if delivered, or if source stops being submitted)
     if (g.DragDropActive)
     {
@@ -5985,6 +6246,9 @@
     // Initiate moving window + handle left-click and right-click focus
     UpdateMouseMovingWindowEndFrame();
 
+    // Update user-facing viewport list (g.Viewports -> g.PlatformIO.Viewports after filtering out some)
+    UpdateViewportsEndFrame();
+
     // Sort the window list so that all child windows are after their parent
     // We cannot do that on FocusWindow() because children may not exist yet
     g.WindowsTempSortBuffer.resize(0);
@@ -6046,7 +6310,7 @@
 
     // Add ImDrawList to render
     ImGuiWindow* windows_to_render_top_most[2];
-    windows_to_render_top_most[0] = (g.NavWindowingTarget && !(g.NavWindowingTarget->Flags & ImGuiWindowFlags_NoBringToFrontOnFocus)) ? g.NavWindowingTarget->RootWindow : NULL;
+    windows_to_render_top_most[0] = (g.NavWindowingTarget && !(g.NavWindowingTarget->Flags & ImGuiWindowFlags_NoBringToFrontOnFocus)) ? g.NavWindowingTarget->RootWindowDockTree : NULL;
     windows_to_render_top_most[1] = (g.NavWindowingTarget ? g.NavWindowingListWindow : NULL);
     for (ImGuiWindow* window : g.Windows)
     {
@@ -6131,8 +6395,15 @@
     ImGuiWindow* hovered_window = NULL;
     ImGuiWindow* hovered_window_under_moving_window = NULL;
 
-    if (find_first_and_in_any_viewport == false && g.MovingWindow && !(g.MovingWindow->Flags & ImGuiWindowFlags_NoMouseInputs))
-        hovered_window = g.MovingWindow;
+    // Special handling for the window being moved: Ignore the mouse viewport check (because it may reset/lose its viewport during the undocking frame)
+    ImGuiViewportP* backup_moving_window_viewport = NULL;
+    if (find_first_and_in_any_viewport == false && g.MovingWindow)
+    {
+        backup_moving_window_viewport = g.MovingWindow->Viewport;
+        g.MovingWindow->Viewport = g.MouseViewport;
+        if (!(g.MovingWindow->Flags & ImGuiWindowFlags_NoMouseInputs))
+            hovered_window = g.MovingWindow;
+    }
 
     ImVec2 padding_regular = g.Style.TouchExtraPadding;
     ImVec2 padding_for_resize = ImMax(g.Style.TouchExtraPadding, ImVec2(g.Style.WindowBorderHoverPadding, g.Style.WindowBorderHoverPadding));
@@ -6144,6 +6415,9 @@
             continue;
         if (window->Flags & ImGuiWindowFlags_NoMouseInputs)
             continue;
+        IM_ASSERT(window->Viewport);
+        if (window->Viewport != g.MouseViewport)
+            continue;
 
         // Using the clipped AABB, a child window will typically be clipped by its parent (not always)
         ImVec2 hit_padding = (window->Flags & (ImGuiWindowFlags_NoResize | ImGuiWindowFlags_AlwaysAutoResize)) ? padding_regular : padding_for_resize;
@@ -6170,7 +6444,7 @@
             if (hovered_window == NULL)
                 hovered_window = window;
             IM_MSVC_WARNING_SUPPRESS(28182); // [Static Analyzer] Dereferencing NULL pointer.
-            if (hovered_window_under_moving_window == NULL && (!g.MovingWindow || window->RootWindow != g.MovingWindow->RootWindow))
+            if (hovered_window_under_moving_window == NULL && (!g.MovingWindow || window->RootWindowDockTree != g.MovingWindow->RootWindowDockTree))
                 hovered_window_under_moving_window = window;
             if (hovered_window && hovered_window_under_moving_window)
                 break;
@@ -6180,6 +6454,8 @@
     *out_hovered_window = hovered_window;
     if (out_hovered_window_under_moving_window != NULL)
         *out_hovered_window_under_moving_window = hovered_window_under_moving_window;
+    if (find_first_and_in_any_viewport == false && g.MovingWindow)
+        g.MovingWindow->Viewport = backup_moving_window_viewport;
 }
 
 bool ImGui::IsItemActive()
@@ -6217,7 +6493,16 @@
 bool ImGui::IsItemFocused()
 {
     ImGuiContext& g = *GImGui;
-    return g.NavId == g.LastItemData.ID && g.NavId != 0;
+    if (g.NavId != g.LastItemData.ID || g.NavId == 0)
+        return false;
+
+    // Special handling for the dummy item after Begin() which represent the title bar or tab.
+    // When the window is collapsed (SkipItems==true) that last item will never be overwritten so we need to detect the case.
+    ImGuiWindow* window = g.CurrentWindow;
+    if (g.LastItemData.ID == window->ID && window->WriteAccessed)
+        return false;
+
+    return true;
 }
 
 // Important: this can be useful but it is NOT equivalent to the behavior of e.g.Button()!
@@ -6381,7 +6666,7 @@
         child_flags &= ~ImGuiChildFlags_ResizeY;
 
     // Set window flags
-    window_flags |= ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_NoTitleBar;
+    window_flags |= ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoDocking;
     window_flags |= (parent_window->Flags & ImGuiWindowFlags_NoMove); // Inherit the NoMove flag
     if (child_flags & (ImGuiChildFlags_AutoResizeX | ImGuiChildFlags_AutoResizeY | ImGuiChildFlags_AlwaysAutoResize))
         window_flags |= ImGuiWindowFlags_AlwaysAutoResize;
@@ -6538,6 +6823,7 @@
     window->SetWindowPosAllowFlags       = enabled ? (window->SetWindowPosAllowFlags       | flags) : (window->SetWindowPosAllowFlags       & ~flags);
     window->SetWindowSizeAllowFlags      = enabled ? (window->SetWindowSizeAllowFlags      | flags) : (window->SetWindowSizeAllowFlags      & ~flags);
     window->SetWindowCollapsedAllowFlags = enabled ? (window->SetWindowCollapsedAllowFlags | flags) : (window->SetWindowCollapsedAllowFlags & ~flags);
+    window->SetWindowDockAllowFlags      = enabled ? (window->SetWindowDockAllowFlags      | flags) : (window->SetWindowDockAllowFlags      & ~flags);
 }
 
 ImGuiWindow* ImGui::FindWindowByID(ImGuiID id)
@@ -6554,10 +6840,19 @@
 
 static void ApplyWindowSettings(ImGuiWindow* window, ImGuiWindowSettings* settings)
 {
-    window->Pos = ImTrunc(ImVec2(settings->Pos.x, settings->Pos.y));
+    const ImGuiViewport* main_viewport = ImGui::GetMainViewport();
+    window->ViewportPos = main_viewport->Pos;
+    if (settings->ViewportId)
+    {
+        window->ViewportId = settings->ViewportId;
+        window->ViewportPos = ImVec2(settings->ViewportPos.x, settings->ViewportPos.y);
+    }
+    window->Pos = ImTrunc(ImVec2(settings->Pos.x + window->ViewportPos.x, settings->Pos.y + window->ViewportPos.y));
     if (settings->Size.x > 0 && settings->Size.y > 0)
         window->Size = window->SizeFull = ImTrunc(ImVec2(settings->Size.x, settings->Size.y));
     window->Collapsed = settings->Collapsed;
+    window->DockId = settings->DockId;
+    window->DockOrder = settings->DockOrder;
 }
 
 static void InitOrLoadWindowSettings(ImGuiWindow* window, ImGuiWindowSettings* settings)
@@ -6567,7 +6862,8 @@
     const ImGuiViewport* main_viewport = ImGui::GetMainViewport();
     window->Pos = main_viewport->Pos + ImVec2(60, 60);
     window->Size = window->SizeFull = ImVec2(0, 0);
-    window->SetWindowPosAllowFlags = window->SetWindowSizeAllowFlags = window->SetWindowCollapsedAllowFlags = ImGuiCond_Always | ImGuiCond_Once | ImGuiCond_FirstUseEver | ImGuiCond_Appearing;
+    window->ViewportPos = main_viewport->Pos;
+    window->SetWindowPosAllowFlags = window->SetWindowSizeAllowFlags = window->SetWindowCollapsedAllowFlags = window->SetWindowDockAllowFlags = ImGuiCond_Always | ImGuiCond_Once | ImGuiCond_FirstUseEver | ImGuiCond_Appearing;
 
     if (settings != NULL)
     {
@@ -6615,6 +6911,16 @@
     return window;
 }
 
+static ImGuiWindow* GetWindowForTitleDisplay(ImGuiWindow* window)
+{
+    return window->DockNodeAsHost ? window->DockNodeAsHost->VisibleWindow : window;
+}
+
+static ImGuiWindow* GetWindowForTitleAndMenuHeight(ImGuiWindow* window)
+{
+    return (window->DockNodeAsHost && window->DockNodeAsHost->VisibleWindow) ? window->DockNodeAsHost->VisibleWindow : window;
+}
+
 static inline ImVec2 CalcWindowMinSize(ImGuiWindow* window)
 {
     // We give windows non-zero minimum size to facilitate understanding problematic cases (e.g. empty popups)
@@ -6634,7 +6940,7 @@
     }
 
     // Reduce artifacts with very small windows
-    ImGuiWindow* window_for_height = window;
+    ImGuiWindow* window_for_height = GetWindowForTitleAndMenuHeight(window);
     size_min.y = ImMax(size_min.y, window_for_height->TitleBarHeight + window_for_height->MenuBarHeight + ImMax(0.0f, g.Style.WindowRounding - 1.0f));
     return size_min;
 }
@@ -6701,7 +7007,15 @@
 
     // Determine maximum window size
     // Child windows are laid within their parent (unless they are also popups/menus) and thus have no restriction
-    ImVec2 size_max = ((window->Flags & ImGuiWindowFlags_ChildWindow) && !(window->Flags & ImGuiWindowFlags_Popup)) ? ImVec2(FLT_MAX, FLT_MAX) : ImGui::GetMainViewport()->WorkSize - style.DisplaySafeAreaPadding * 2.0f;
+    ImVec2 size_max = ImVec2(FLT_MAX, FLT_MAX);
+    if ((window->Flags & ImGuiWindowFlags_ChildWindow) == 0 || (window->Flags & ImGuiWindowFlags_Popup) != 0)
+    {
+        if (!window->ViewportOwned)
+            size_max = ImGui::GetMainViewport()->WorkSize - style.DisplaySafeAreaPadding * 2.0f;
+        const int monitor_idx = window->ViewportAllowPlatformMonitorExtend;
+        if (monitor_idx >= 0 && monitor_idx < g.PlatformIO.Monitors.Size)
+            size_max = g.PlatformIO.Monitors[monitor_idx].WorkSize - style.DisplaySafeAreaPadding * 2.0f;
+    }
 
     if (window->Flags & ImGuiWindowFlags_Tooltip)
     {
@@ -6740,7 +7054,7 @@
 {
     if (window->Flags & (ImGuiWindowFlags_Tooltip | ImGuiWindowFlags_Popup))
         return ImGuiCol_PopupBg;
-    if (window->Flags & ImGuiWindowFlags_ChildWindow)
+    if ((window->Flags & ImGuiWindowFlags_ChildWindow) && !window->DockIsActive)
         return ImGuiCol_ChildBg;
     return ImGuiCol_WindowBg;
 }
@@ -6818,7 +7132,7 @@
 ImGuiID ImGui::GetWindowResizeCornerID(ImGuiWindow* window, int n)
 {
     IM_ASSERT(n >= 0 && n < 4);
-    ImGuiID id = window->ID;
+    ImGuiID id = window->DockIsActive ? window->DockNode->HostWindow->ID : window->ID;
     id = ImHashStr("#RESIZE", 0, id);
     id = ImHashData(&n, sizeof(int), id);
     return id;
@@ -6829,7 +7143,7 @@
 {
     IM_ASSERT(dir >= 0 && dir < 4);
     int n = (int)dir + 4;
-    ImGuiID id = window->ID;
+    ImGuiID id = window->DockIsActive ? window->DockNode->HostWindow->ID : window->ID;
     id = ImHashStr("#RESIZE", 0, id);
     id = ImHashData(&n, sizeof(int), id);
     return id;
@@ -6862,6 +7176,16 @@
     ImVec2 pos_target(FLT_MAX, FLT_MAX);
     ImVec2 size_target(FLT_MAX, FLT_MAX);
 
+    // Clip mouse interaction rectangles within the viewport rectangle (in practice the narrowing is going to happen most of the time).
+    // - Not narrowing would mostly benefit the situation where OS windows _without_ decoration have a threshold for hovering when outside their limits.
+    //   This is however not the case with current backends under Win32, but a custom borderless window implementation would benefit from it.
+    // - When decoration are enabled we typically benefit from that distance, but then our resize elements would be conflicting with OS resize elements, so we also narrow.
+    // - Note that we are unable to tell if the platform setup allows hovering with a distance threshold (on Win32, decorated window have such threshold).
+    // We only clip interaction so we overwrite window->ClipRect, cannot call PushClipRect() yet as DrawList is not yet setup.
+    const bool clip_with_viewport_rect = !(g.IO.BackendFlags & ImGuiBackendFlags_HasMouseHoveredViewport) || (g.IO.MouseHoveredViewport != window->ViewportId) || !(window->Viewport->Flags & ImGuiViewportFlags_NoDecoration);
+    if (clip_with_viewport_rect)
+        window->ClipRect = window->Viewport->GetMainRect();
+
     // Resize grips and borders are on layer 1
     window->DC.NavLayerCurrent = ImGuiNavLayer_Menu;
 
@@ -6949,7 +7273,7 @@
             // Switch to relative resizing mode when border geometry moved (e.g. resizing a child altering parent scroll), in order to avoid resizing feedback loop.
             // Currently only using relative mode on resizable child windows, as the problem to solve is more likely noticeable for them, but could apply for all windows eventually.
             // FIXME: May want to generalize this idiom at lower-level, so more widgets can use it!
-            const bool just_scrolled_manually_while_resizing = (g.WheelingWindow != NULL && g.WheelingWindowScrolledFrame == g.FrameCount && IsWindowChildOf(window, g.WheelingWindow, false));
+            const bool just_scrolled_manually_while_resizing = (g.WheelingWindow != NULL && g.WheelingWindowScrolledFrame == g.FrameCount && IsWindowChildOf(window, g.WheelingWindow, false, true));
             if (g.ActiveIdIsJustActivated || just_scrolled_manually_while_resizing)
             {
                 g.WindowResizeBorderExpectedRect = border_rect;
@@ -6996,7 +7320,7 @@
     // Navigation resize (keyboard/gamepad)
     // FIXME: This cannot be moved to NavUpdateWindowing() because CalcWindowSizeAfterConstraint() need to callback into user.
     // Not even sure the callback works here.
-    if (g.NavWindowingTarget && g.NavWindowingTarget->RootWindow == window)
+    if (g.NavWindowingTarget && g.NavWindowingTarget->RootWindowDockTree == window)
     {
         ImVec2 nav_resize_dir;
         if (g.NavInputSource == ImGuiInputSource_Keyboard && g.IO.KeyShift)
@@ -7046,7 +7370,10 @@
 static inline void ClampWindowPos(ImGuiWindow* window, const ImRect& visibility_rect)
 {
     ImVec2 size_for_clamping = window->Size;
-    if (!(window->BgClickFlags & ImGuiWindowBgClickFlags_Move) && !(window->Flags & ImGuiWindowFlags_NoTitleBar))
+    const bool move_from_title_bar_only = (window->BgClickFlags & ImGuiWindowBgClickFlags_Move) == 0;
+    if (move_from_title_bar_only && window->DockNodeAsHost)
+        size_for_clamping.y = ImGui::GetFrameHeight(); // Not using window->TitleBarHeight() as DockNodeAsHost will report 0.0f here.
+    else if (move_from_title_bar_only && !(window->Flags & ImGuiWindowFlags_NoTitleBar))
         size_for_clamping.y = window->TitleBarHeight;
     window->Pos = ImClamp(window->Pos, visibility_rect.Min - size_for_clamping, visibility_rect.Max);
 }
@@ -7081,7 +7408,7 @@
         const ImU32 border_col_resizing = GetColorU32((window->ResizeBorderHeld != -1) ? ImGuiCol_SeparatorActive : ImGuiCol_SeparatorHovered);
         RenderWindowOuterSingleBorder(window, border_n, border_col_resizing, ImMax(2.0f, window->WindowBorderSize)); // Thicker than usual
     }
-    if (g.Style.FrameBorderSize > 0 && !(window->Flags & ImGuiWindowFlags_NoTitleBar))
+    if (g.Style.FrameBorderSize > 0 && !(window->Flags & ImGuiWindowFlags_NoTitleBar) && !window->DockIsActive)
     {
         float y = window->Pos.y + window->TitleBarHeight - 1;
         window->DrawList->AddLine(ImVec2(window->Pos.x + border_size * 0.5f, y), ImVec2(window->Pos.x + window->Size.x - border_size * 0.5f, y), border_col, g.Style.FrameBorderSize);
@@ -7111,6 +7438,8 @@
         const float backup_border_size = style.FrameBorderSize;
         g.Style.FrameBorderSize = window->WindowBorderSize;
         ImU32 title_bar_col = GetColorU32((title_bar_is_highlight && g.NavCursorVisible) ? ImGuiCol_TitleBgActive : ImGuiCol_TitleBgCollapsed);
+        if (window->ViewportOwned)
+            title_bar_col |= IM_COL32_A_MASK; // No alpha (we don't support is_docking_transparent_payload here because simpler and less meaningful, but could with a bit of code shuffle/reuse)
         RenderFrame(title_bar_rect.Min, title_bar_rect.Max, title_bar_col, true, window_rounding);
         g.Style.FrameBorderSize = backup_border_size;
     }
@@ -7119,29 +7448,69 @@
         // Window background
         if (!(flags & ImGuiWindowFlags_NoBackground))
         {
+            bool is_docking_transparent_payload = false;
+            if (g.DragDropActive && (g.FrameCount - g.DragDropAcceptFrameCount) <= 1 && g.IO.ConfigDockingTransparentPayload)
+                if (g.DragDropPayload.IsDataType(IMGUI_PAYLOAD_TYPE_WINDOW) && *(ImGuiWindow**)g.DragDropPayload.Data == window)
+                    is_docking_transparent_payload = true;
+
             ImU32 bg_col = GetColorU32(GetWindowBgColorIdx(window));
-            bool override_alpha = false;
-            float alpha = 1.0f;
-            if (g.NextWindowData.HasFlags & ImGuiNextWindowDataFlags_HasBgAlpha)
+            if (window->ViewportOwned)
             {
-                alpha = g.NextWindowData.BgAlphaVal;
-                override_alpha = true;
+                bg_col |= IM_COL32_A_MASK; // No alpha
+                if (is_docking_transparent_payload)
+                    window->Viewport->Alpha *= DOCKING_TRANSPARENT_PAYLOAD_ALPHA;
             }
-            if (override_alpha)
-                bg_col = (bg_col & ~IM_COL32_A_MASK) | (IM_F32_TO_INT8_SAT(alpha) << IM_COL32_A_SHIFT);
+            else
+            {
+                // Adjust alpha. For docking
+                bool override_alpha = false;
+                float alpha = 1.0f;
+                if (g.NextWindowData.HasFlags & ImGuiNextWindowDataFlags_HasBgAlpha)
+                {
+                    alpha = g.NextWindowData.BgAlphaVal;
+                    override_alpha = true;
+                }
+                if (is_docking_transparent_payload)
+                {
+                    alpha *= DOCKING_TRANSPARENT_PAYLOAD_ALPHA; // FIXME-DOCK: Should that be an override?
+                    override_alpha = true;
+                }
+                if (override_alpha)
+                    bg_col = (bg_col & ~IM_COL32_A_MASK) | (IM_F32_TO_INT8_SAT(alpha) << IM_COL32_A_SHIFT);
+            }
+
+            // Render, for docked windows and host windows we ensure BG goes before decorations
+            if (window->DockIsActive)
+                window->DockNode->LastBgColor = bg_col;
+            if (flags & ImGuiWindowFlags_DockNodeHost)
+                bg_col = 0;
             if (bg_col & IM_COL32_A_MASK)
             {
                 ImRect bg_rect(window->Pos + ImVec2(0, window->TitleBarHeight), window->Pos + window->Size);
-                ImDrawFlags bg_rounding_flags = (flags & ImGuiWindowFlags_NoTitleBar) ? 0 : ImDrawFlags_RoundCornersBottom;
-                ImDrawList* bg_draw_list = window->DrawList;
+                ImDrawFlags bg_rounding_flags;
+                if (window->DockIsActive)
+                    bg_rounding_flags = CalcRoundingFlagsForRectInRect(bg_rect, window->DockNode->HostWindow->Rect(), 0.0f);
+                else
+                    bg_rounding_flags = (flags & ImGuiWindowFlags_NoTitleBar) ? ImDrawFlags_RoundCornersAll : ImDrawFlags_RoundCornersBottom;
+                ImDrawList* bg_draw_list = window->DockIsActive ? window->DockNode->HostWindow->DrawList : window->DrawList;
+                if (window->DockIsActive)
+                    bg_draw_list->ChannelsSetCurrent(DOCKING_HOST_DRAW_CHANNEL_BG);
                 bg_draw_list->AddRectFilled(bg_rect.Min, bg_rect.Max, bg_col, window_rounding, bg_rounding_flags);
+                if (window->DockIsActive)
+                    bg_draw_list->ChannelsSetCurrent(DOCKING_HOST_DRAW_CHANNEL_FG);
             }
         }
+        if (window->DockIsActive)
+            window->DockNode->IsBgDrawnThisFrame = true;
 
         // Title bar
-        if (!(flags & ImGuiWindowFlags_NoTitleBar))
+        // (when docked, DockNode are drawing their own title bar. Individual windows however do NOT set the _NoTitleBar flag,
+        // in order for their pos/size to be matching their undocking state.)
+        if (!(flags & ImGuiWindowFlags_NoTitleBar) && !window->DockIsActive)
         {
             ImU32 title_bar_col = GetColorU32(title_bar_is_highlight ? ImGuiCol_TitleBgActive : ImGuiCol_TitleBg);
+            if (window->ViewportOwned)
+                title_bar_col |= IM_COL32_A_MASK; // No alpha
             window->DrawList->AddRectFilled(title_bar_rect.Min, title_bar_rect.Max, title_bar_col, window_rounding, ImDrawFlags_RoundCornersTop);
         }
 
@@ -7155,6 +7524,27 @@
                 window->DrawList->AddLine(menu_bar_rect.GetBL() + ImVec2(window_border_size * 0.5f, 0.0f), menu_bar_rect.GetBR() - ImVec2(window_border_size * 0.5f, 0.0f), GetColorU32(ImGuiCol_Border), style.FrameBorderSize);
         }
 
+        // Docking: Unhide tab bar (small triangle in the corner), drag from small triangle to quickly undock
+        ImGuiDockNode* node = window->DockNode;
+        if (window->DockIsActive && node->IsHiddenTabBar() && !node->IsNoTabBar())
+        {
+            float unhide_sz_draw = ImTrunc(g.FontSize * 0.70f);
+            float unhide_sz_hit = ImTrunc(g.FontSize * 0.55f);
+            ImVec2 p = node->Pos;
+            ImRect r(p, p + ImVec2(unhide_sz_hit, unhide_sz_hit));
+            ImGuiID unhide_id = window->GetID("#UNHIDE");
+            KeepAliveID(unhide_id);
+            bool hovered, held;
+            if (ButtonBehavior(r, unhide_id, &hovered, &held, ImGuiButtonFlags_FlattenChildren))
+                node->WantHiddenTabBarToggle = true;
+            else if (held && IsMouseDragging(0))
+                StartMouseMovingWindowOrNode(window, node, true); // Undock from tab-bar triangle = same as window/collapse menu button
+
+            // FIXME-DOCK: Ideally we'd use ImGuiCol_TitleBgActive/ImGuiCol_TitleBg here, but neither is guaranteed to be visible enough at this sort of size..
+            ImU32 col = GetColorU32(((held && hovered) || (node->IsFocused && !hovered)) ? ImGuiCol_ButtonActive : hovered ? ImGuiCol_ButtonHovered : ImGuiCol_Button);
+            window->DrawList->AddTriangleFilled(p, p + ImVec2(unhide_sz_draw, 0.0f), p + ImVec2(0.0f, unhide_sz_draw), col);
+        }
+
         // Scrollbars
         if (window->ScrollbarX)
             Scrollbar(ImGuiAxis_X);
@@ -7179,13 +7569,14 @@
             }
         }
 
-        // Borders
-        if (handle_borders_and_resize_grips)
+        // Borders (for dock node host they will be rendered over after the tab bar)
+        if (handle_borders_and_resize_grips && !window->DockNodeAsHost)
             RenderWindowOuterBorders(window);
     }
     window->DC.NavLayerCurrent = ImGuiNavLayer_Main;
 }
 
+// When inside a dock node, this is handled in DockNodeCalcTabBarLayout() instead.
 // Render title text, collapse button, close button
 void ImGui::RenderWindowTitleBarContents(ImGuiWindow* window, const ImRect& title_bar_rect, const char* name, bool* p_open)
 {
@@ -7227,7 +7618,7 @@
 
     // Collapse button (submitting first so it gets priority when choosing a navigation init fallback)
     if (has_collapse_button)
-        if (CollapseButton(window->GetID("#COLLAPSE"), collapse_button_pos))
+        if (CollapseButton(window->GetID("#COLLAPSE"), collapse_button_pos, NULL))
             window->WantCollapseToggle = true; // Defer actual collapsing to next frame as we are too far in the Begin() function
 
     // Close button
@@ -7283,12 +7674,16 @@
 void ImGui::UpdateWindowParentAndRootLinks(ImGuiWindow* window, ImGuiWindowFlags flags, ImGuiWindow* parent_window)
 {
     window->ParentWindow = parent_window;
-    window->RootWindow = window->RootWindowPopupTree = window->RootWindowForTitleBarHighlight = window->RootWindowForNav = window;
+    window->RootWindow = window->RootWindowPopupTree = window->RootWindowDockTree = window->RootWindowForTitleBarHighlight = window->RootWindowForNav = window;
     if (parent_window && (flags & ImGuiWindowFlags_ChildWindow) && !(flags & ImGuiWindowFlags_Tooltip))
-        window->RootWindow = parent_window->RootWindow;
+    {
+        window->RootWindowDockTree = parent_window->RootWindowDockTree;
+        if (!window->DockIsActive && !(parent_window->Flags & ImGuiWindowFlags_DockNodeHost))
+            window->RootWindow = parent_window->RootWindow;
+    }
     if (parent_window && (flags & ImGuiWindowFlags_Popup))
         window->RootWindowPopupTree = parent_window->RootWindowPopupTree;
-    if (parent_window && !(flags & ImGuiWindowFlags_Modal) && (flags & (ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_Popup | ImGuiWindowFlags_Tooltip)))
+    if (parent_window && !(flags & ImGuiWindowFlags_Modal) && (flags & (ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_Popup | ImGuiWindowFlags_Tooltip))) // FIXME: simply use _NoTitleBar ?
         window->RootWindowForTitleBarHighlight = parent_window->RootWindowForTitleBarHighlight;
     while (window->RootWindowForNav->ChildFlags & ImGuiChildFlags_NavFlattened)
     {
@@ -7367,22 +7762,24 @@
     const bool first_begin_of_the_frame = (window->LastFrameActive != current_frame);
     window->IsFallbackWindow = (g.CurrentWindowStack.Size == 0 && g.WithinFrameScopeWithImplicitWindow);
 
-    // Update the Appearing flag
-    bool window_just_activated_by_user = (window->LastFrameActive < current_frame - 1);   // Not using !WasActive because the implicit "Debug" window would always toggle off->on
+    // Update the Appearing flag (note: the BeginDocked() path may also set this to true later)
+    bool window_just_activated_by_user = (window->LastFrameActive < current_frame - 1); // Not using !WasActive because the implicit "Debug" window would always toggle off->on
     if (flags & ImGuiWindowFlags_Popup)
     {
         ImGuiPopupData& popup_ref = g.OpenPopupStack[g.BeginPopupStack.Size];
         window_just_activated_by_user |= (window->PopupId != popup_ref.PopupId); // We recycle popups so treat window as activated if popup id changed
         window_just_activated_by_user |= (window != popup_ref.Window);
     }
-    window->Appearing = window_just_activated_by_user;
-    if (window->Appearing)
-        SetWindowConditionAllowFlags(window, ImGuiCond_Appearing, true);
 
     // Update Flags, LastFrameActive, BeginOrderXXX fields
+    const bool window_was_appearing = window->Appearing;
     if (first_begin_of_the_frame)
     {
         UpdateWindowInFocusOrderList(window, window_just_created, flags);
+        window->Appearing = window_just_activated_by_user;
+        if (window->Appearing)
+            SetWindowConditionAllowFlags(window, ImGuiCond_Appearing, true);
+        window->FlagsPreviousFrame = window->Flags;
         window->Flags = (ImGuiWindowFlags)flags;
         window->ChildFlags = (g.NextWindowData.HasFlags & ImGuiNextWindowDataFlags_HasChildFlags) ? g.NextWindowData.ChildFlags : 0;
         window->LastFrameActive = current_frame;
@@ -7395,8 +7792,40 @@
         flags = window->Flags;
     }
 
+    // Docking
+    // (NB: during the frame dock nodes are created, it is possible that (window->DockIsActive == false) even though (window->DockNode->Windows.Size > 1)
+    IM_ASSERT(window->DockNode == NULL || window->DockNodeAsHost == NULL); // Cannot be both
+    if (g.NextWindowData.HasFlags & ImGuiNextWindowDataFlags_HasDock)
+        SetWindowDock(window, g.NextWindowData.DockId, g.NextWindowData.DockCond);
+    if (first_begin_of_the_frame)
+    {
+        const bool has_dock_node = (window->DockId != 0 || window->DockNode != NULL);
+        const bool new_auto_dock_node = !has_dock_node && GetWindowAlwaysWantOwnTabBar(window);
+        const bool dock_node_was_visible = window->DockNodeIsVisible;
+        const bool dock_tab_was_visible = window->DockTabIsVisible;
+        window->DockIsActive = window->DockNodeIsVisible = window->DockTabIsVisible = false;
+
+        if (has_dock_node || new_auto_dock_node)
+        {
+            BeginDocked(window, p_open);
+            flags = window->Flags;
+            if (window->DockIsActive)
+            {
+                IM_ASSERT(window->DockNode != NULL);
+                g.NextWindowData.HasFlags &= ~ImGuiNextWindowDataFlags_HasSizeConstraint; // Docking currently override constraints
+            }
+
+            // Amend the Appearing flag
+            if (window->DockTabIsVisible && !dock_tab_was_visible && dock_node_was_visible && !window->Appearing && !window_was_appearing)
+            {
+                window->Appearing = true;
+                SetWindowConditionAllowFlags(window, ImGuiCond_Appearing, true);
+            }
+        }
+    }
+
     // Parent window is latched only on the first call to Begin() of the frame, so further append-calls can be done from a different window stack
-    ImGuiWindow* parent_window_in_stack = g.CurrentWindowStack.empty() ? NULL : g.CurrentWindowStack.back().Window;
+    ImGuiWindow* parent_window_in_stack = (window->DockIsActive && window->DockNode->HostWindow) ? window->DockNode->HostWindow : g.CurrentWindowStack.empty() ? NULL : g.CurrentWindowStack.back().Window;
     ImGuiWindow* parent_window = first_begin_of_the_frame ? ((flags & (ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_Popup | ImGuiWindowFlags_Tooltip)) ? parent_window_in_stack : NULL) : window->ParentWindow;
     IM_ASSERT(parent_window != NULL || !(flags & ImGuiWindowFlags_ChildWindow));
 
@@ -7423,11 +7852,22 @@
         UpdateWindowParentAndRootLinks(window, flags, parent_window);
         window->ParentWindowInBeginStack = parent_window_in_stack;
 
+        // Focus route
         // There's little point to expose a flag to set this: because the interesting cases won't be using parent_window_in_stack,
-        // e.g. linking a tool window in a standalone viewport to a document window, regardless of their Begin() stack parenting. (#6798)
-        window->ParentWindowForFocusRoute = (flags & ImGuiWindowFlags_ChildWindow) ? parent_window_in_stack : NULL;
+        // Use for e.g. linking a tool window in a standalone viewport to a document window, regardless of their Begin() stack parenting. (#6798)
+        window->ParentWindowForFocusRoute = (window->RootWindow != window) ? parent_window_in_stack : NULL;
+        if (window->ParentWindowForFocusRoute == NULL && window->DockNode != NULL)
+            if (window->DockNode->MergedFlags & ImGuiDockNodeFlags_DockedWindowsInFocusRoute)
+                window->ParentWindowForFocusRoute = window->DockNode->HostWindow;
 
-        // Inherent SetWindowFontScale() from parent until we fix this system...
+        // Override with SetNextWindowClass() field or direct call to SetWindowParentWindowForFocusRoute()
+        if (window->WindowClass.FocusRouteParentWindowId != 0)
+        {
+            window->ParentWindowForFocusRoute = FindWindowByID(window->WindowClass.FocusRouteParentWindowId);
+            IM_ASSERT(window->ParentWindowForFocusRoute != 0); // Invalid value for FocusRouteParentWindowId.
+        }
+
+        // Inherit SetWindowFontScale() from parent until we fix this system...
         window->FontWindowScaleParents = parent_window ? parent_window->FontWindowScaleParents * parent_window->FontWindowScale : 1.0f;
     }
 
@@ -7492,6 +7932,8 @@
         window->ContentSizeExplicit = g.NextWindowData.ContentSizeVal;
     else if (first_begin_of_the_frame)
         window->ContentSizeExplicit = ImVec2(0.0f, 0.0f);
+    if (g.NextWindowData.HasFlags & ImGuiNextWindowDataFlags_HasWindowClass)
+        window->WindowClass = g.NextWindowData.WindowClass;
     if (g.NextWindowData.HasFlags & ImGuiNextWindowDataFlags_HasCollapsed)
         SetWindowCollapsed(window, g.NextWindowData.CollapsedVal, g.NextWindowData.CollapsedCond);
     if (g.NextWindowData.HasFlags & ImGuiNextWindowDataFlags_HasFocus)
@@ -7521,6 +7963,11 @@
         window->IDStack.resize(1);
         window->DrawList->_ResetForNewFrame();
         window->DC.CurrentTableIdx = -1;
+        if (flags & ImGuiWindowFlags_DockNodeHost)
+        {
+            window->DrawList->ChannelsSplit(2);
+            window->DrawList->ChannelsSetCurrent(DOCKING_HOST_DRAW_CHANNEL_FG); // Render decorations on channel 1 as we will render the backgrounds manually later
+        }
 
         // Restore buffer capacity when woken from a compacted state, to avoid
         if (window->MemoryCompacted)
@@ -7529,9 +7976,11 @@
         // Update stored window name when it changes (which can _only_ happen with the "###" operator, so the ID would stay unchanged).
         // The title bar always display the 'name' parameter, so we only update the string storage if it needs to be visible to the end-user elsewhere.
         bool window_title_visible_elsewhere = false;
-        if (g.NavWindowingListWindow != NULL && g.NavWindowingListWindow->WasActive && (flags & ImGuiWindowFlags_NoNavFocus) == 0)   // Window titles visible when using Ctrl+Tab
+        if ((window->Viewport && window->Viewport->Window == window) || (window->DockIsActive))
             window_title_visible_elsewhere = true;
-        if (flags & ImGuiWindowFlags_ChildMenu)
+        else if (g.NavWindowingListWindow != NULL && g.NavWindowingListWindow->WasActive && (flags & ImGuiWindowFlags_NoNavFocus) == 0)   // Window titles visible when using Ctrl+Tab
+            window_title_visible_elsewhere = true;
+        else if (flags & ImGuiWindowFlags_ChildMenu)
             window_title_visible_elsewhere = true;
         if ((window_title_visible_elsewhere || window_just_activated_by_user) && !window_just_created && strcmp(name, window->Name) != 0)
         {
@@ -7544,6 +7993,10 @@
 
         // Update contents size from last frame for auto-fitting (or use explicit size)
         CalcWindowContentSizes(window, &window->ContentSize, &window->ContentSizeIdeal);
+
+        // FIXME: These flags are decremented before they are used. This means that in order to have these fields produce their intended behaviors
+        // for one frame we must set them to at least 2, which is counter-intuitive. HiddenFramesCannotSkipItems is a more complicated case because
+        // it has a single usage before this code block and may be set below before it is finally checked.
         if (window->HiddenFramesCanSkipItems > 0)
             window->HiddenFramesCanSkipItems--;
         if (window->HiddenFramesCannotSkipItems > 0)
@@ -7571,20 +8024,22 @@
         }
 
         // SELECT VIEWPORT
-        // FIXME-VIEWPORT: In the docking/viewport branch, this is the point where we select the current viewport (which may affect the style)
+        // We need to do this before using any style/font sizes, as viewport with a different DPI may affect font sizes.
 
-        ImGuiViewportP* viewport = (ImGuiViewportP*)(void*)GetMainViewport();
-        SetWindowViewport(window, viewport);
+        WindowSelectViewport(window);
+        SetCurrentViewport(window, window->Viewport);
         SetCurrentWindow(window);
+        flags = window->Flags;
 
         // LOCK BORDER SIZE AND PADDING FOR THE FRAME (so that altering them doesn't cause inconsistencies)
+        // We read Style data after the call to UpdateSelectWindowViewport() which might be swapping the style.
 
-        if (flags & ImGuiWindowFlags_ChildWindow)
+        if (!window->DockIsActive && (flags & ImGuiWindowFlags_ChildWindow))
             window->WindowBorderSize = style.ChildBorderSize;
         else
             window->WindowBorderSize = ((flags & (ImGuiWindowFlags_Popup | ImGuiWindowFlags_Tooltip)) && !(flags & ImGuiWindowFlags_Modal)) ? style.PopupBorderSize : style.WindowBorderSize;
         window->WindowPadding = style.WindowPadding;
-        if ((flags & ImGuiWindowFlags_ChildWindow) && !(flags & ImGuiWindowFlags_Popup) && !(window->ChildFlags & ImGuiChildFlags_AlwaysUseWindowPadding) && window->WindowBorderSize == 0.0f)
+        if (!window->DockIsActive && (flags & ImGuiWindowFlags_ChildWindow) && !(flags & ImGuiWindowFlags_Popup) && !(window->ChildFlags & ImGuiChildFlags_AlwaysUseWindowPadding) && window->WindowBorderSize == 0.0f)
             window->WindowPadding = ImVec2(0.0f, (flags & ImGuiWindowFlags_MenuBar) ? style.WindowPadding.y : 0.0f);
 
         // Lock menu offset so size calculation can use it as menu-bar windows need a minimum size.
@@ -7605,7 +8060,7 @@
 
         // Collapse window by double-clicking on title bar
         // At this point we don't have a clipping rectangle setup yet, so we can use the title bar area for hit detection and drawing
-        if (!(flags & ImGuiWindowFlags_NoTitleBar) && !(flags & ImGuiWindowFlags_NoCollapse))
+        if (!(flags & ImGuiWindowFlags_NoTitleBar) && !(flags & ImGuiWindowFlags_NoCollapse) && !window->DockIsActive)
         {
             // We don't use a regular button+id to test for double-click on title bar (mostly due to legacy reason, could be fixed),
             // so verify that we don't have items over the title bar.
@@ -7709,23 +8164,67 @@
         else if ((flags & ImGuiWindowFlags_Tooltip) != 0 && !window_pos_set_by_api && !window_is_child_tooltip)
             window->Pos = FindBestWindowPosForPopup(window);
 
+        // Late create viewport if we don't fit within our current host viewport.
+        if (window->ViewportAllowPlatformMonitorExtend >= 0 && !window->ViewportOwned && !(window->Viewport->Flags & ImGuiViewportFlags_IsMinimized))
+            if (!window->Viewport->GetMainRect().Contains(window->Rect()))
+            {
+                // This is based on the assumption that the DPI will be known ahead (same as the DPI of the selection done in UpdateSelectWindowViewport)
+                //ImGuiViewport* old_viewport = window->Viewport;
+                window->Viewport = AddUpdateViewport(window, window->ID, window->Pos, window->Size, ImGuiViewportFlags_NoFocusOnAppearing);
+
+                // FIXME-DPI
+                //IM_ASSERT(old_viewport->DpiScale == window->Viewport->DpiScale); // FIXME-DPI: Something went wrong
+                SetCurrentViewport(window, window->Viewport);
+                SetCurrentWindow(window);
+            }
+
+        if (window->ViewportOwned)
+            WindowSyncOwnedViewport(window, parent_window_in_stack);
+
         // Calculate the range of allowed position for that window (to be movable and visible past safe area padding)
         // When clamping to stay visible, we will enforce that window->Pos stays inside of visibility_rect.
-        ImRect viewport_rect(viewport->GetMainRect());
-        ImRect viewport_work_rect(viewport->GetWorkRect());
+        ImRect viewport_rect(window->Viewport->GetMainRect());
+        ImRect viewport_work_rect(window->Viewport->GetWorkRect());
         ImVec2 visibility_padding = ImMax(style.DisplayWindowPadding, style.DisplaySafeAreaPadding);
         ImRect visibility_rect(viewport_work_rect.Min + visibility_padding, viewport_work_rect.Max - visibility_padding);
 
         // Clamp position/size so window stays visible within its viewport or monitor
         // Ignore zero-sized display explicitly to avoid losing positions if a window manager reports zero-sized window when initializing or minimizing.
+        // FIXME: Similar to code in GetWindowAllowedExtentRect()
         if (!window_pos_set_by_api && !(flags & ImGuiWindowFlags_ChildWindow))
-            if (viewport_rect.GetWidth() > 0.0f && viewport_rect.GetHeight() > 0.0f)
+        {
+            if (!window->ViewportOwned && viewport_rect.GetWidth() > 0 && viewport_rect.GetHeight() > 0.0f)
+            {
                 ClampWindowPos(window, visibility_rect);
+            }
+            else if (window->ViewportOwned && g.PlatformIO.Monitors.Size > 0)
+            {
+                if (g.MovingWindow != NULL && window->RootWindowDockTree == g.MovingWindow->RootWindowDockTree)
+                {
+                    // While moving windows we allow them to straddle monitors (#7299, #3071)
+                    visibility_rect = g.PlatformMonitorsFullWorkRect;
+                }
+                else
+                {
+                    // When not moving ensure visible in its monitor
+                    // Lost windows (e.g. a monitor disconnected) will naturally moved to the fallback/dummy monitor aka the main viewport.
+                    const ImGuiPlatformMonitor* monitor = GetViewportPlatformMonitor(window->Viewport);
+                    visibility_rect = ImRect(monitor->WorkPos, monitor->WorkPos + monitor->WorkSize);
+                }
+                visibility_rect.Expand(-visibility_padding);
+                ClampWindowPos(window, visibility_rect);
+            }
+        }
         window->Pos = ImTrunc(window->Pos);
 
         // Lock window rounding for the frame (so that altering them doesn't cause inconsistencies)
         // Large values tend to lead to variety of artifacts and are not recommended.
-        window->WindowRounding = (flags & ImGuiWindowFlags_ChildWindow) ? style.ChildRounding : ((flags & ImGuiWindowFlags_Popup) && !(flags & ImGuiWindowFlags_Modal)) ? style.PopupRounding : style.WindowRounding;
+        if ((flags & ImGuiWindowFlags_ChildWindow) && !window->DockIsActive)
+            window->WindowRounding = style.ChildRounding;
+        else if (window->RootWindowDockTree->ViewportOwned)
+            window->WindowRounding = 0.0f;
+        else
+            window->WindowRounding = ((flags & ImGuiWindowFlags_Popup) && !(flags & ImGuiWindowFlags_Modal)) ? style.PopupRounding : style.WindowRounding;
 
         // For windows with title bar or menu bar, we clamp to FrameHeight(FontSize + FramePadding.y * 2.0f) to completely hide artifacts.
         //if ((window->Flags & ImGuiWindowFlags_MenuBar) || !(window->Flags & ImGuiWindowFlags_NoTitleBar))
@@ -7737,7 +8236,7 @@
         {
             if (flags & ImGuiWindowFlags_Popup)
                 want_focus = true;
-            else if ((flags & (ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_Tooltip)) == 0)
+            else if ((window->DockIsActive || (flags & ImGuiWindowFlags_ChildWindow) == 0) && !(flags & ImGuiWindowFlags_Tooltip))
                 want_focus = true;
         }
 
@@ -7759,7 +8258,7 @@
         // Decide if we are going to handle borders and resize grips
         // 'window->SkipItems' is not updated yet so for child windows we rely on ParentWindow to avoid submitting decorations. (#8815)
         // Whenever we add support for full decorated child windows we will likely make this logic more general.
-        bool handle_borders_and_resize_grips = true;
+        bool handle_borders_and_resize_grips = (window->DockNodeAsHost || !window->DockIsActive);
         if ((flags & ImGuiWindowFlags_ChildWindow) && window->ParentWindow->SkipItems)
             handle_borders_and_resize_grips = false;
 
@@ -7785,6 +8284,20 @@
         window->ResizeBorderHovered = (signed char)border_hovered;
         window->ResizeBorderHeld = (signed char)border_held;
 
+        // Synchronize window --> viewport again and one last time (clamping and manual resize may have affected either)
+        if (window->ViewportOwned)
+        {
+            if (!window->Viewport->PlatformRequestMove)
+                window->Viewport->Pos = window->Pos;
+            if (!window->Viewport->PlatformRequestResize)
+                window->Viewport->Size = window->Size;
+            window->Viewport->UpdateWorkRect();
+            viewport_rect = window->Viewport->GetMainRect();
+        }
+
+        // Save last known viewport position within the window itself (so it can be saved in .ini file and restored)
+        window->ViewportPos = window->Viewport->Pos;
+
         // SCROLLBAR VISIBILITY
 
         // Update scrollbar visibility (based on the Size that was effective during last frame or the auto-resized Size).
@@ -7837,6 +8350,8 @@
         const ImRect outer_rect = window->Rect();
         const ImRect title_bar_rect = window->TitleBarRect();
         window->OuterRectClipped = outer_rect;
+        if (window->DockIsActive)
+            window->OuterRectClipped.Min.y += window->TitleBarHeight;
         window->OuterRectClipped.ClipWith(host_rect);
 
         // Inner rectangle
@@ -7893,6 +8408,8 @@
         // Child windows can render their decoration (bg color, border, scrollbars, etc.) within their parent to save a draw call (since 1.71)
         // When using overlapping child windows, this will break the assumption that child z-order is mapped to submission order.
         // FIXME: User code may rely on explicit sorting of overlapping child window and would need to disable this somehow. Please get in contact if you are affected (github #4493)
+        const bool is_undocked_or_docked_visible = !window->DockIsActive || window->DockTabIsVisible;
+        if (is_undocked_or_docked_visible)
         {
             bool render_decorations_in_parent = false;
             if ((flags & ImGuiWindowFlags_ChildWindow) && !(flags & ImGuiWindowFlags_Popup) && !window_is_child_tooltip)
@@ -7910,7 +8427,7 @@
 
             // Handle title bar, scrollbar, resize grips and resize borders
             const ImGuiWindow* window_to_highlight = g.NavWindowingTarget ? g.NavWindowingTarget : g.NavWindow;
-            const bool title_bar_is_highlight = want_focus || (window_to_highlight && window->RootWindowForTitleBarHighlight == window_to_highlight->RootWindowForTitleBarHighlight);
+            const bool title_bar_is_highlight = want_focus || (window_to_highlight && (window->RootWindowForTitleBarHighlight == window_to_highlight->RootWindowForTitleBarHighlight || (window->DockNode && window->DockNode == window_to_highlight->DockNode)));
             RenderWindowDecorations(window, title_bar_rect, title_bar_is_highlight, handle_borders_and_resize_grips, resize_grip_count, resize_grip_col, resize_grip_draw_size);
 
             if (render_decorations_in_parent)
@@ -7999,6 +8516,9 @@
         if (window->AutoFitFramesY > 0)
             window->AutoFitFramesY--;
 
+        // Clear SetNextWindowXXX data (can aim to move this higher in the function)
+        g.NextWindowData.ClearFlags();
+
         // Apply focus (we need to call FocusWindow() AFTER setting DC.CursorStartPos so our initial navigation reference rectangle can start around there)
         // We ImGuiFocusRequestFlags_UnlessBelowModal to:
         // - Avoid focusing a window that is created outside of a modal. This will prevent active modal from being closed.
@@ -8008,6 +8528,16 @@
         if (want_focus && window == g.NavWindow)
             NavInitWindow(window, false); // <-- this is in the way for us to be able to defer and sort reappearing FocusWindow() calls
 
+        // Close requested by platform window (apply to all windows in this viewport)
+        // FIXME: Investigate removing the 'window->Viewport != GetMainViewport()' test, which seems superfluous.
+        if (p_open != NULL && window->Viewport->PlatformRequestClose && window->Viewport != GetMainViewport())
+            if (window->DockNode == NULL || (window->DockNode->MergedFlags & ImGuiDockNodeFlags_DockSpace) == 0)
+            {
+                IMGUI_DEBUG_LOG_VIEWPORT("[viewport] Window '%s' closed by PlatformRequestClose\n", window->Name);
+                *p_open = false;
+                g.NavWindowingToggleLayer = false; // Assume user mapped PlatformRequestClose on Alt-F4 so we disable Alt for menu toggle. False positive not an issue. // FIXME-NAV: Try removing.
+            }
+
         // Pressing Ctrl+C copy window content into the clipboard
         // [EXPERIMENTAL] Breaks on nested Begin/End pairs. We need to work that out and add better logging scope.
         // [EXPERIMENTAL] Text outputs has many issues.
@@ -8016,8 +8546,10 @@
                 LogToClipboard(0);
 
         // Title bar
-        if (!(flags & ImGuiWindowFlags_NoTitleBar))
+        if (!(flags & ImGuiWindowFlags_NoTitleBar) && !window->DockIsActive)
             RenderWindowTitleBarContents(window, ImRect(title_bar_rect.Min.x + window->WindowBorderSize, title_bar_rect.Min.y, title_bar_rect.Max.x - window->WindowBorderSize, title_bar_rect.Max.y), name, p_open);
+        else if (!(flags & ImGuiWindowFlags_NoTitleBar) && window->DockIsActive)
+            LogText("%.*s\n", (int)(FindRenderedTextEnd(window->Name) - window->Name), window->Name);
 
         // Clear hit test shape every frame
         window->HitTestHoleSize.x = window->HitTestHoleSize.y = 0;
@@ -8025,6 +8557,20 @@
         if (flags & ImGuiWindowFlags_Tooltip)
             g.TooltipPreviousWindow = window;
 
+        if (g.IO.ConfigFlags & ImGuiConfigFlags_DockingEnable)
+        {
+            // Docking: Dragging a dockable window (or any of its child) turns it into a drag and drop source.
+            // We need to do this _before_ we overwrite window->DC.LastItemId below because BeginDockableDragDropSource() also overwrites it.
+            if (g.MovingWindow == window && (window->RootWindowDockTree->Flags & ImGuiWindowFlags_NoDocking) == 0)
+                BeginDockableDragDropSource(window);
+
+            // Docking: Any dockable window can act as a target. For dock node hosts we call BeginDockableDragDropTarget() in DockNodeUpdate() instead.
+            if (g.DragDropActive && !(flags & ImGuiWindowFlags_NoDocking))
+                if (g.MovingWindow == NULL || g.MovingWindow->RootWindowDockTree != window)
+                    if ((window == window->RootWindowDockTree) && !(window->Flags & ImGuiWindowFlags_DockNodeHost))
+                        BeginDockableDragDropTarget(window);
+        }
+
         // Set default BgClickFlags
         // This is set at the end of this function, so UpdateWindowManualResize()/ClampWindowPos() may use last-frame value if overridden by user code.
         // FIXME: The general intent is that we will later expose config options to default to enable scrolling + select scrolling mouse button.
@@ -8059,26 +8605,39 @@
             SetWindowActiveForSkipRefresh(window);
 
         // Append
+        SetCurrentViewport(window, window->Viewport);
         SetCurrentWindow(window);
+        g.NextWindowData.ClearFlags();
         SetLastItemDataForWindow(window, window->TitleBarRect());
     }
 
-    if (!window->SkipRefresh)
+    if (!(flags & ImGuiWindowFlags_DockNodeHost) && !window->SkipRefresh)
         PushClipRect(window->InnerClipRect.Min, window->InnerClipRect.Max, true);
 
     // Clear 'accessed' flag last thing (After PushClipRect which will set the flag. We want the flag to stay false when the default "Debug" window is unused)
     window->WriteAccessed = false;
     window->BeginCount++;
-    g.NextWindowData.ClearFlags();
 
     // Update visibility
     if (first_begin_of_the_frame && !window->SkipRefresh)
     {
+        // When we are about to select this tab (which will only be visible on the _next frame_), flag it with a non-zero HiddenFramesCannotSkipItems.
+        // This will have the important effect of actually returning true in Begin() and not setting SkipItems, allowing an earlier submission of the window contents.
+        // This is analogous to regular windows being hidden from one frame.
+        // It is especially important as e.g. nested TabBars would otherwise generate flicker in the form of one empty frame, or focus requests won't be processed.
+        if (window->DockIsActive && !window->DockTabIsVisible)
+        {
+            if (window->LastFrameJustFocused == g.FrameCount)
+                window->HiddenFramesCannotSkipItems = 1;
+            else
+                window->HiddenFramesCanSkipItems = 1;
+        }
+
         if ((flags & ImGuiWindowFlags_ChildWindow) && !(flags & ImGuiWindowFlags_ChildMenu))
         {
             // Child window can be out of sight and have "negative" clip windows.
             // Mark them as collapsed so commands are skipped earlier (we can't manually collapse them because they have no title bar).
-            IM_ASSERT((flags & ImGuiWindowFlags_NoTitleBar) != 0);
+            IM_ASSERT((flags & ImGuiWindowFlags_NoTitleBar) != 0 || window->DockIsActive);
             const bool nav_request = (window->ChildFlags & ImGuiChildFlags_NavFlattened) && (g.NavAnyRequest && g.NavWindow && g.NavWindow->RootWindowForNav == window->RootWindowForNav);
             if (!g.LogEnabled && !nav_request)
                 if (window->OuterRectClipped.Min.x >= window->OuterRectClipped.Max.x || window->OuterRectClipped.Min.y >= window->OuterRectClipped.Max.y)
@@ -8117,6 +8676,16 @@
             if (window->AutoFitFramesX <= 0 && window->AutoFitFramesY <= 0 && window->HiddenFramesCannotSkipItems <= 0)
                 skip_items = true;
         window->SkipItems = skip_items;
+
+        // Restore NavLayersActiveMaskNext to previous value when not visible, so a CTRL+Tab back can use a safe value.
+        if (window->SkipItems)
+            window->DC.NavLayersActiveMaskNext = window->DC.NavLayersActiveMask;
+
+        // Sanity check: there are two spots which can set Appearing = true
+        // - when 'window_just_activated_by_user' is set -> HiddenFramesCannotSkipItems is set -> SkipItems always false
+        // - in BeginDocked() path when DockNodeIsVisible == DockTabIsVisible == true -> hidden _should_ be all zero // FIXME: Not formally proven, hence the assert.
+        if (window->SkipItems && !window->Appearing)
+            IM_ASSERT(window->Appearing == false); // Please report on GitHub if this triggers: https://github.com/ocornut/imgui/issues/4177
     }
     else if (first_begin_of_the_frame)
     {
@@ -8153,14 +8722,14 @@
     ImGuiWindowStackData& window_stack_data = g.CurrentWindowStack.back();
 
     // Error checking: verify that user doesn't directly call End() on a child window.
-    if (window->Flags & ImGuiWindowFlags_ChildWindow)
+    if ((window->Flags & ImGuiWindowFlags_ChildWindow) && !(window->Flags & ImGuiWindowFlags_DockNodeHost) && !window->DockIsActive)
         IM_ASSERT_USER_ERROR(g.WithinEndChildID == window->ID, "Must call EndChild() and not End()!");
 
     // Close anything that is open
     if (window->DC.CurrentColumns)
         EndColumns();
-    if (!window->SkipRefresh)
-        PopClipRect();   // Inner window clip rectangle
+    if (!(window->Flags & ImGuiWindowFlags_DockNodeHost) && !window->SkipRefresh)   // Pop inner window clip rectangle
+        PopClipRect();
     PopFocusScope();
     if (window_stack_data.DisabledOverrideReenable && window->RootWindow == window)
         EndDisabledOverrideReenable();
@@ -8178,6 +8747,11 @@
     if (window->DC.IsSetPos)
         ErrorCheckUsingSetCursorPosToExtendParentBoundaries();
 
+    // Docking: report contents sizes to parent to allow for auto-resize
+    if (window->DockNode && window->DockTabIsVisible)
+        if (ImGuiWindow* host_window = window->DockNode->HostWindow)         // FIXME-DOCK
+            host_window->DC.CursorMaxPos = window->DC.CursorMaxPos + window->WindowPadding - host_window->WindowPadding;
+
     // Pop from window stack
     g.LastItemData = window_stack_data.ParentLastItemDataBackup;
     if (window->Flags & ImGuiWindowFlags_ChildMenu)
@@ -8191,6 +8765,8 @@
 
     g.CurrentWindowStack.pop_back();
     SetCurrentWindow(g.CurrentWindowStack.Size == 0 ? NULL : g.CurrentWindowStack.back().Window);
+    if (g.CurrentWindow)
+        SetCurrentViewport(g.CurrentWindow, g.CurrentWindow->Viewport);
 }
 
 void ImGui::PushItemFlag(ImGuiItemFlags option, bool enabled)
@@ -8291,7 +8867,7 @@
     window->DC.TextWrapPosStack.pop_back();
 }
 
-static ImGuiWindow* GetCombinedRootWindow(ImGuiWindow* window, bool popup_hierarchy)
+static ImGuiWindow* GetCombinedRootWindow(ImGuiWindow* window, bool popup_hierarchy, bool dock_hierarchy)
 {
     ImGuiWindow* last_window = NULL;
     while (last_window != window)
@@ -8300,13 +8876,15 @@
         window = window->RootWindow;
         if (popup_hierarchy)
             window = window->RootWindowPopupTree;
-    }
+		if (dock_hierarchy)
+			window = window->RootWindowDockTree;
+	}
     return window;
 }
 
-bool ImGui::IsWindowChildOf(ImGuiWindow* window, ImGuiWindow* potential_parent, bool popup_hierarchy)
+bool ImGui::IsWindowChildOf(ImGuiWindow* window, ImGuiWindow* potential_parent, bool popup_hierarchy, bool dock_hierarchy)
 {
-    ImGuiWindow* window_root = GetCombinedRootWindow(window, popup_hierarchy);
+    ImGuiWindow* window_root = GetCombinedRootWindow(window, popup_hierarchy, dock_hierarchy);
     if (window_root == potential_parent)
         return true;
     while (window != NULL)
@@ -8380,12 +8958,13 @@
     {
         IM_ASSERT(cur_window); // Not inside a Begin()/End()
         const bool popup_hierarchy = (flags & ImGuiHoveredFlags_NoPopupHierarchy) == 0;
+        const bool dock_hierarchy = (flags & ImGuiHoveredFlags_DockHierarchy) != 0;
         if (flags & ImGuiHoveredFlags_RootWindow)
-            cur_window = GetCombinedRootWindow(cur_window, popup_hierarchy);
+            cur_window = GetCombinedRootWindow(cur_window, popup_hierarchy, dock_hierarchy);
 
         bool result;
         if (flags & ImGuiHoveredFlags_ChildWindows)
-            result = IsWindowChildOf(ref_window, cur_window, popup_hierarchy);
+            result = IsWindowChildOf(ref_window, cur_window, popup_hierarchy, dock_hierarchy);
         else
             result = (ref_window == cur_window);
         if (!result)
@@ -8411,6 +8990,18 @@
     return true;
 }
 
+ImGuiID ImGui::GetWindowDockID()
+{
+    ImGuiContext& g = *GImGui;
+    return g.CurrentWindow->DockId;
+}
+
+bool ImGui::IsWindowDocked()
+{
+    ImGuiContext& g = *GImGui;
+    return g.CurrentWindow->DockIsActive;
+}
+
 float ImGui::GetWindowWidth()
 {
     ImGuiWindow* window = GImGui->CurrentWindow;
@@ -8447,6 +9038,7 @@
     if (offset.x == 0.0f && offset.y == 0.0f)
         return;
     MarkIniSettingsDirty(window);
+    // FIXME: share code with TranslateWindow(), need to confirm whether the 3 rect modified by TranslateWindow() are desirable here.
     window->DC.CursorPos += offset;         // As we happen to move the window while it is being appended to (which is a bad idea - will smear) let's at least offset the cursor
     window->DC.CursorMaxPos += offset;      // And more importantly we need to offset CursorMaxPos/CursorStartPos this so ContentSize calculation doesn't get affected.
     window->DC.IdealMaxPos += offset;
@@ -8568,6 +9160,7 @@
     g.NextWindowData.PosVal = pos;
     g.NextWindowData.PosPivotVal = pivot;
     g.NextWindowData.PosCond = cond ? cond : ImGuiCond_Always;
+    g.NextWindowData.PosUndock = true;
 }
 
 void ImGui::SetNextWindowSize(const ImVec2& size, ImGuiCond cond)
@@ -8624,6 +9217,29 @@
     g.NextWindowData.BgAlphaVal = alpha;
 }
 
+void ImGui::SetNextWindowViewport(ImGuiID id)
+{
+    ImGuiContext& g = *GImGui;
+    g.NextWindowData.HasFlags |= ImGuiNextWindowDataFlags_HasViewport;
+    g.NextWindowData.ViewportId = id;
+}
+
+void ImGui::SetNextWindowDockID(ImGuiID id, ImGuiCond cond)
+{
+    ImGuiContext& g = *GImGui;
+    g.NextWindowData.HasFlags |= ImGuiNextWindowDataFlags_HasDock;
+    g.NextWindowData.DockCond = cond ? cond : ImGuiCond_Always;
+    g.NextWindowData.DockId = id;
+}
+
+void ImGui::SetNextWindowClass(const ImGuiWindowClass* window_class)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT((window_class->ViewportFlagsOverrideSet & window_class->ViewportFlagsOverrideClear) == 0); // Cannot set both set and clear for the same bit
+    g.NextWindowData.HasFlags |= ImGuiNextWindowDataFlags_HasWindowClass;
+    g.NextWindowData.WindowClass = *window_class;
+}
+
 // This is experimental and meant to be a toy for exploring a future/wider range of features.
 void ImGui::SetNextWindowRefreshPolicy(ImGuiWindowRefreshFlags flags)
 {
@@ -8638,6 +9254,19 @@
     return window->DrawList;
 }
 
+float ImGui::GetWindowDpiScale()
+{
+    ImGuiContext& g = *GImGui;
+    return g.CurrentDpiScale;
+}
+
+ImGuiViewport* ImGui::GetWindowViewport()
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(g.CurrentViewport != NULL && g.CurrentViewport == g.CurrentWindow->Viewport);
+    return g.CurrentViewport;
+}
+
 ImFont* ImGui::GetFont()
 {
     return GImGui->Font;
@@ -9905,6 +10534,8 @@
     // Hit testing, expanded for touch input
     if (!rect_clipped.ContainsWithPad(g.IO.MousePos, g.Style.TouchExtraPadding))
         return false;
+    if (!g.MouseViewport->GetMainRect().Overlaps(rect_clipped))
+        return false;
     return true;
 }
 
@@ -10162,13 +10793,16 @@
             io.MouseClickedTime[i] = g.Time;
             io.MouseClickedPos[i] = io.MousePos;
             io.MouseClickedCount[i] = io.MouseClickedLastCount[i];
+            io.MouseDragMaxDistanceAbs[i] = ImVec2(0.0f, 0.0f);
             io.MouseDragMaxDistanceSqr[i] = 0.0f;
         }
         else if (io.MouseDown[i])
         {
             // Maintain the maximum distance we reaching from the initial click position, which is used with dragging threshold
-            float delta_sqr_click_pos = IsMousePosValid(&io.MousePos) ? ImLengthSqr(io.MousePos - io.MouseClickedPos[i]) : 0.0f;
-            io.MouseDragMaxDistanceSqr[i] = ImMax(io.MouseDragMaxDistanceSqr[i], delta_sqr_click_pos);
+            ImVec2 delta_from_click_pos = IsMousePosValid(&io.MousePos) ? (io.MousePos - io.MouseClickedPos[i]) : ImVec2(0.0f, 0.0f);
+            io.MouseDragMaxDistanceSqr[i] = ImMax(io.MouseDragMaxDistanceSqr[i], ImLengthSqr(delta_from_click_pos));
+            io.MouseDragMaxDistanceAbs[i].x = ImMax(io.MouseDragMaxDistanceAbs[i].x, delta_from_click_pos.x < 0.0f ? -delta_from_click_pos.x : delta_from_click_pos.x);
+            io.MouseDragMaxDistanceAbs[i].y = ImMax(io.MouseDragMaxDistanceAbs[i].y, delta_from_click_pos.y < 0.0f ? -delta_from_click_pos.y : delta_from_click_pos.y);
         }
 
         // We provide io.MouseDoubleClicked[] as a legacy service
@@ -10364,6 +10998,7 @@
     if (e->Type == ImGuiInputEventType_MousePos)    { if (e->MousePos.PosX == -FLT_MAX && e->MousePos.PosY == -FLT_MAX) IMGUI_DEBUG_LOG_IO("[io] %s: MousePos (-FLT_MAX, -FLT_MAX)\n", prefix); else IMGUI_DEBUG_LOG_IO("[io] %s: MousePos (%.1f, %.1f) (%s)\n", prefix, e->MousePos.PosX, e->MousePos.PosY, GetMouseSourceName(e->MousePos.MouseSource)); return; }
     if (e->Type == ImGuiInputEventType_MouseButton) { IMGUI_DEBUG_LOG_IO("[io] %s: MouseButton %d %s (%s)\n", prefix, e->MouseButton.Button, e->MouseButton.Down ? "Down" : "Up", GetMouseSourceName(e->MouseButton.MouseSource)); return; }
     if (e->Type == ImGuiInputEventType_MouseWheel)  { IMGUI_DEBUG_LOG_IO("[io] %s: MouseWheel (%.3f, %.3f) (%s)\n", prefix, e->MouseWheel.WheelX, e->MouseWheel.WheelY, GetMouseSourceName(e->MouseWheel.MouseSource)); return; }
+    if (e->Type == ImGuiInputEventType_MouseViewport){IMGUI_DEBUG_LOG_IO("[io] %s: MouseViewport (0x%08X)\n", prefix, e->MouseViewport.HoveredViewportID); return; }
     if (e->Type == ImGuiInputEventType_Key)         { IMGUI_DEBUG_LOG_IO("[io] %s: Key \"%s\" %s\n", prefix, ImGui::GetKeyName(e->Key.Key), e->Key.Down ? "Down" : "Up"); return; }
     if (e->Type == ImGuiInputEventType_Text)        { ImTextCharToUtf8(buf, e->Text.Char); IMGUI_DEBUG_LOG_IO("[io] %s: Text: '%s' (U+%08X)\n", prefix, buf, e->Text.Char); return; }
     if (e->Type == ImGuiInputEventType_Focus)       { IMGUI_DEBUG_LOG_IO("[io] %s: AppFocused %d\n", prefix, e->AppFocused.Focused); return; }
@@ -10427,6 +11062,10 @@
             io.MouseSource = e->MouseWheel.MouseSource;
             mouse_wheeled = true;
         }
+        else if (e->Type == ImGuiInputEventType_MouseViewport)
+        {
+            io.MouseHoveredViewport = e->MouseViewport.HoveredViewportID;
+        }
         else if (e->Type == ImGuiInputEventType_Key)
         {
             // Trickling Rule: Stop processing queued events if we got multiple action on the same button
@@ -10844,6 +11483,16 @@
         g.IO.ConfigNavCaptureKeyboard = false;
         g.IO.ConfigFlags &= ~ImGuiConfigFlags_NavNoCaptureKeyboard;
     }
+    if (g.IO.ConfigFlags & ImGuiConfigFlags_DpiEnableScaleFonts)
+    {
+        g.IO.ConfigDpiScaleFonts = true;
+        g.IO.ConfigFlags &= ~ImGuiConfigFlags_DpiEnableScaleFonts;
+    }
+    if (g.IO.ConfigFlags & ImGuiConfigFlags_DpiEnableScaleViewports)
+    {
+        g.IO.ConfigDpiScaleViewports = true;
+        g.IO.ConfigFlags &= ~ImGuiConfigFlags_DpiEnableScaleViewports;
+    }
 
     // Remap legacy clipboard handlers (OBSOLETED in 1.91.1, August 2024)
     if (g.IO.GetClipboardTextFn != NULL && (g.PlatformIO.Platform_GetClipboardTextFn == NULL || g.PlatformIO.Platform_GetClipboardTextFn == Platform_GetClipboardTextFn_DefaultImpl))
@@ -10851,6 +11500,45 @@
     if (g.IO.SetClipboardTextFn != NULL && (g.PlatformIO.Platform_SetClipboardTextFn == NULL || g.PlatformIO.Platform_SetClipboardTextFn == Platform_SetClipboardTextFn_DefaultImpl))
         g.PlatformIO.Platform_SetClipboardTextFn = [](ImGuiContext* ctx, const char* text) { return ctx->IO.SetClipboardTextFn(ctx->IO.ClipboardUserData, text); };
 #endif
+
+    // Perform simple check: error if Docking or Viewport are enabled _exactly_ on frame 1 (instead of frame 0 or later), which is a common error leading to loss of .ini data.
+    if (g.FrameCount == 1 && (g.IO.ConfigFlags & ImGuiConfigFlags_DockingEnable) && (g.ConfigFlagsLastFrame & ImGuiConfigFlags_DockingEnable) == 0)
+        IM_ASSERT(0 && "Please set DockingEnable before the first call to NewFrame()! Otherwise you will lose your .ini settings!");
+    if (g.FrameCount == 1 && (g.IO.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) && (g.ConfigFlagsLastFrame & ImGuiConfigFlags_ViewportsEnable) == 0)
+        IM_ASSERT(0 && "Please set ViewportsEnable before the first call to NewFrame()! Otherwise you will lose your .ini settings!");
+
+    // Perform simple checks: multi-viewport and platform windows support
+    if (g.IO.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+    {
+        if ((g.IO.BackendFlags & ImGuiBackendFlags_PlatformHasViewports) && (g.IO.BackendFlags & ImGuiBackendFlags_RendererHasViewports))
+        {
+            IM_ASSERT((g.FrameCount == 0 || g.FrameCount == g.FrameCountPlatformEnded) && "Forgot to call UpdatePlatformWindows() in main loop after EndFrame()? Check examples/ applications for reference.");
+            IM_ASSERT(g.PlatformIO.Platform_CreateWindow  != NULL && "Platform init didn't install handlers?");
+            IM_ASSERT(g.PlatformIO.Platform_DestroyWindow != NULL && "Platform init didn't install handlers?");
+            IM_ASSERT(g.PlatformIO.Platform_GetWindowPos  != NULL && "Platform init didn't install handlers?");
+            IM_ASSERT(g.PlatformIO.Platform_SetWindowPos  != NULL && "Platform init didn't install handlers?");
+            IM_ASSERT(g.PlatformIO.Platform_GetWindowSize != NULL && "Platform init didn't install handlers?");
+            IM_ASSERT(g.PlatformIO.Platform_SetWindowSize != NULL && "Platform init didn't install handlers?");
+            IM_ASSERT(g.PlatformIO.Monitors.Size > 0 && "Platform init didn't setup Monitors list?");
+            IM_ASSERT((g.Viewports[0]->PlatformUserData != NULL || g.Viewports[0]->PlatformHandle != NULL) && "Platform init didn't setup main viewport.");
+            if (g.IO.ConfigDockingTransparentPayload && (g.IO.ConfigFlags & ImGuiConfigFlags_DockingEnable))
+                IM_ASSERT(g.PlatformIO.Platform_SetWindowAlpha != NULL && "Platform_SetWindowAlpha handler is required to use io.ConfigDockingTransparent!");
+        }
+        else
+        {
+            // Disable feature, our backends do not support it
+            g.IO.ConfigFlags &= ~ImGuiConfigFlags_ViewportsEnable;
+        }
+
+        // Perform simple checks on platform monitor data + compute a total bounding box for quick early outs
+        for (ImGuiPlatformMonitor& mon : g.PlatformIO.Monitors)
+        {
+            IM_UNUSED(mon);
+            IM_ASSERT(mon.MainSize.x > 0.0f && mon.MainSize.y > 0.0f && "Monitor main bounds not setup properly.");
+            IM_ASSERT(ImRect(mon.MainPos, mon.MainPos + mon.MainSize).Contains(ImRect(mon.WorkPos, mon.WorkPos + mon.WorkSize)) && "Monitor work bounds not setup properly. If you don't have work area information, just copy MainPos/MainSize into them.");
+            IM_ASSERT(mon.DpiScale > 0.0f && mon.DpiScale < 99.0f && "Monitor DpiScale is invalid."); // Typical correct values would be between 1.0f and 4.0f
+        }
+    }
 }
 
 static void ImGui::ErrorCheckEndFrameSanityChecks()
@@ -11989,7 +12677,7 @@
     const char* window_name_template = is_dragdrop_tooltip ? "##Tooltip_DragDrop_%02d" : "##Tooltip_%02d";
     char window_name[32];
     ImFormatString(window_name, IM_COUNTOF(window_name), window_name_template, g.TooltipOverrideCount);
-    ImGuiWindowFlags flags = ImGuiWindowFlags_Tooltip | ImGuiWindowFlags_NoInputs | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_AlwaysAutoResize;
+    ImGuiWindowFlags flags = ImGuiWindowFlags_Tooltip | ImGuiWindowFlags_NoInputs | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoDocking;
     Begin(window_name, NULL, flags | extra_window_flags);
     // 2023-03-09: Added bool return value to the API, but currently always returning true.
     // If this ever returns false we need to update BeginDragDropSource() accordingly.
@@ -12062,8 +12750,8 @@
         if (popup_flags & ImGuiPopupFlags_AnyPopupLevel)
         {
             // Return true if the popup is open anywhere in the popup stack
-            for (int n = 0; n < g.OpenPopupStack.Size; n++)
-                if (g.OpenPopupStack[n].PopupId == id)
+            for (ImGuiPopupData& popup_data : g.OpenPopupStack)
+                if (popup_data.PopupId == id)
                     return true;
             return false;
         }
@@ -12239,12 +12927,13 @@
             //     Window -> Popup1 -> Window2(Ref)
             // - Clicking/focusing Popup1 will close Popup2 and Popup3:
             //     Window -> Popup1(Ref) -> Popup2 -> Popup3
-            // - Each popups may contain child windows, which is why we compare ->RootWindow!
+            // - Each popups may contain child windows, which is why we compare ->RootWindowDockTree!
             //     Window -> Popup1 -> Popup1_Child -> Popup2 -> Popup2_Child
             // We step through every popup from bottom to top to validate their position relative to reference window.
             bool ref_window_is_descendent_of_popup = false;
             for (int n = popup_count_to_keep; n < g.OpenPopupStack.Size; n++)
                 if (ImGuiWindow* popup_window = g.OpenPopupStack[n].Window)
+                    //if (popup_window->RootWindowDockTree == ref_window->RootWindowDockTree) // FIXME-MERGE
                     if (IsWindowWithinBeginStackOf(ref_window, popup_window))
                     {
                         ref_window_is_descendent_of_popup = true;
@@ -12346,7 +13035,7 @@
     IM_ASSERT((extra_window_flags & ImGuiWindowFlags_ChildMenu) == 0); // Use BeginPopupMenuEx()
     ImFormatString(name, IM_COUNTOF(name), "##Popup_%08x", id); // No recycling, so we can close/open during the same frame
 
-    bool is_open = Begin(name, NULL, extra_window_flags | ImGuiWindowFlags_Popup);
+    bool is_open = Begin(name, NULL, extra_window_flags | ImGuiWindowFlags_Popup | ImGuiWindowFlags_NoDocking);
     if (!is_open) // NB: Begin can return false when the popup is completely clipped (e.g. zero size display)
         EndPopup();
     //g.CurrentWindow->FocusRouteParentWindow = g.CurrentWindow->ParentWindowInBeginStack;
@@ -12407,11 +13096,11 @@
     // FIXME: Should test for (PosCond & window->SetWindowPosAllowFlags) with the upcoming window.
     if ((g.NextWindowData.HasFlags & ImGuiNextWindowDataFlags_HasPos) == 0)
     {
-        const ImGuiViewport* viewport = GetMainViewport();
+        const ImGuiViewport* viewport = window->WasActive ? window->Viewport : GetMainViewport(); // FIXME-VIEWPORT: What may be our reference viewport?
         SetNextWindowPos(viewport->GetCenter(), ImGuiCond_FirstUseEver, ImVec2(0.5f, 0.5f));
     }
 
-    flags |= ImGuiWindowFlags_Popup | ImGuiWindowFlags_Modal | ImGuiWindowFlags_NoCollapse;
+    flags |= ImGuiWindowFlags_Popup | ImGuiWindowFlags_Modal | ImGuiWindowFlags_NoCollapse | ImGuiWindowFlags_NoDocking;
     const bool is_open = Begin(name, p_open, flags);
     if (!is_open || (p_open && !*p_open)) // NB: is_open can be 'false' when the popup is completely clipped (e.g. zero size display)
     {
@@ -12610,8 +13299,19 @@
 ImRect ImGui::GetPopupAllowedExtentRect(ImGuiWindow* window)
 {
     ImGuiContext& g = *GImGui;
-    IM_UNUSED(window);
-    ImRect r_screen = ((ImGuiViewportP*)(void*)GetMainViewport())->GetMainRect();
+    ImRect r_screen;
+    if (window->ViewportAllowPlatformMonitorExtend >= 0)
+    {
+        // Extent with be in the frame of reference of the given viewport (so Min is likely to be negative here)
+        const ImGuiPlatformMonitor& monitor = g.PlatformIO.Monitors[window->ViewportAllowPlatformMonitorExtend];
+        r_screen.Min = monitor.WorkPos;
+        r_screen.Max = monitor.WorkPos + monitor.WorkSize;
+    }
+    else
+    {
+        // Use the full viewport area (not work area) for popups
+        r_screen = window->Viewport->GetMainRect();
+    }
     ImVec2 padding = g.Style.DisplaySafeAreaPadding;
     r_screen.Expand(ImVec2((r_screen.GetWidth() > padding.x * 2) ? -padding.x : 0.0f, (r_screen.GetHeight() > padding.y * 2) ? -padding.y : 0.0f));
     return r_screen;
@@ -12626,8 +13326,7 @@
     {
         // Child menus typically request _any_ position within the parent menu item, and then we move the new menu outside the parent bounds.
         // This is how we end up with child menus appearing (most-commonly) on the right of the parent menu.
-        IM_ASSERT(g.CurrentWindow == window);
-        ImGuiWindow* parent_window = g.CurrentWindowStack[g.CurrentWindowStack.Size - 2].Window;
+        ImGuiWindow* parent_window = window->ParentWindow;
         float horizontal_overlap = g.Style.ItemInnerSpacing.x; // We want some overlap to convey the relative depth of each menu (currently the amount of overlap is hard-coded to style.ItemSpacing.x).
         ImRect r_avoid;
         if (parent_window->DC.MenuBarAppending)
@@ -12727,11 +13426,12 @@
 
     IM_ASSERT(cur_window); // Not inside a Begin()/End()
     const bool popup_hierarchy = (flags & ImGuiFocusedFlags_NoPopupHierarchy) == 0;
+    const bool dock_hierarchy = (flags & ImGuiFocusedFlags_DockHierarchy) != 0;
     if (flags & ImGuiFocusedFlags_RootWindow)
-        cur_window = GetCombinedRootWindow(cur_window, popup_hierarchy);
+        cur_window = GetCombinedRootWindow(cur_window, popup_hierarchy, dock_hierarchy);
 
     if (flags & ImGuiFocusedFlags_ChildWindows)
-        return IsWindowChildOf(ref_window, cur_window, popup_hierarchy);
+        return IsWindowChildOf(ref_window, cur_window, popup_hierarchy, dock_hierarchy);
     else
         return ref_window == cur_window;
 }
@@ -12796,7 +13496,7 @@
 {
     ImGuiContext& g = *GImGui;
     ImGuiWindow* current_front_window = g.Windows.back();
-    if (current_front_window == window || current_front_window->RootWindow == window) // Cheap early out (could be better)
+    if (current_front_window == window || current_front_window->RootWindowDockTree == window) // Cheap early out (could be better)
         return;
     for (int i = g.Windows.Size - 2; i >= 0; i--) // We can ignore the top-most window
         if (g.Windows[i] == window)
@@ -12889,31 +13589,39 @@
     }
 
     // Move the root window to the top of the pile
-    IM_ASSERT(window == NULL || window->RootWindow != NULL);
-    ImGuiWindow* focus_front_window = window ? window->RootWindow : NULL; // NB: In docking branch this is window->RootWindowDockStop
-    ImGuiWindow* display_front_window = window ? window->RootWindow : NULL;
+    IM_ASSERT(window == NULL || window->RootWindowDockTree != NULL);
+    ImGuiWindow* focus_front_window = window ? window->RootWindow : NULL;
+    ImGuiWindow* display_front_window = window ? window->RootWindowDockTree : NULL;
+    ImGuiDockNode* dock_node = window ? window->DockNode : NULL;
+    bool active_id_window_is_dock_node_host = (g.ActiveIdWindow && dock_node && dock_node->HostWindow == g.ActiveIdWindow);
 
     // Steal active widgets. Some of the cases it triggers includes:
     // - Focus a window while an InputText in another window is active, if focus happens before the old InputText can run.
     // - When using Nav to activate menu items (due to timing of activating on press->new window appears->losing ActiveId)
+    // - Using dock host items (tab, collapse button) can trigger this before we redirect the ActiveIdWindow toward the child window.
     if (g.ActiveId != 0 && g.ActiveIdWindow && g.ActiveIdWindow->RootWindow != focus_front_window)
-        if (!g.ActiveIdNoClearOnFocusLoss)
+        if (!g.ActiveIdNoClearOnFocusLoss && !active_id_window_is_dock_node_host)
             ClearActiveID();
 
     // Passing NULL allow to disable keyboard focus
     if (!window)
         return;
+    window->LastFrameJustFocused = g.FrameCount;
+
+    // Select in dock node
+    // For #2304 we avoid applying focus immediately before the tabbar is visible.
+    //if (dock_node && dock_node->TabBar)
+    //    dock_node->TabBar->SelectedTabId = dock_node->TabBar->NextSelectedTabId = window->TabId;
 
     // Bring to front
     BringWindowToFocusFront(focus_front_window);
-    if (((window->Flags | display_front_window->Flags) & ImGuiWindowFlags_NoBringToFrontOnFocus) == 0)
+    if (((window->Flags | focus_front_window->Flags | display_front_window->Flags) & ImGuiWindowFlags_NoBringToFrontOnFocus) == 0)
         BringWindowToDisplayFront(display_front_window);
 }
 
 void ImGui::FocusTopMostWindowUnderOne(ImGuiWindow* under_this_window, ImGuiWindow* ignore_window, ImGuiViewport* filter_viewport, ImGuiFocusRequestFlags flags)
 {
     ImGuiContext& g = *GImGui;
-    IM_UNUSED(filter_viewport); // Unused in master branch.
     int start_idx = g.WindowsFocusOrder.Size - 1;
     if (under_this_window != NULL)
     {
@@ -12932,8 +13640,15 @@
         ImGuiWindow* window = g.WindowsFocusOrder[i];
         if (window == ignore_window || !window->WasActive)
             continue;
+        if (filter_viewport != NULL && window->Viewport != filter_viewport)
+            continue;
         if ((window->Flags & (ImGuiWindowFlags_NoMouseInputs | ImGuiWindowFlags_NoNavInputs)) != (ImGuiWindowFlags_NoMouseInputs | ImGuiWindowFlags_NoNavInputs))
         {
+            // FIXME-DOCK: When ImGuiFocusRequestFlags_RestoreFocusedChild is set...
+            // This is failing (lagging by one frame) for docked windows.
+            // If A and B are docked into window and B disappear, at the NewFrame() call site window->NavLastChildNavWindow will still point to B.
+            // We might leverage the tab order implicitly stored in window->DockNodeAsHost->TabBar (essentially the 'most_recently_selected_tab' code in tab bar will do that but on next update)
+            // to tell which is the "previous" window. Or we may leverage 'LastFrameFocused/LastFrameJustFocused' and have this function handle child window itself?
             FocusWindow(window, flags);
             return;
         }
@@ -13480,6 +14195,9 @@
 {
     if (window->NavLastChildNavWindow && window->NavLastChildNavWindow->WasActive)
         return window->NavLastChildNavWindow;
+    if (window->DockNodeAsHost && window->DockNodeAsHost->TabBar)
+        if (ImGuiTabItem* tab = TabBarFindMostRecentlySelectedTabForActiveWindow(window->DockNodeAsHost->TabBar))
+            return tab->Window;
     return window;
 }
 
@@ -13517,6 +14235,7 @@
 // This needs to be called before we submit any widget (aka in or before Begin)
 void ImGui::NavInitWindow(ImGuiWindow* window, bool force_reinit)
 {
+    // FIXME: ChildWindow test here is wrong for docking
     ImGuiContext& g = *GImGui;
     IM_ASSERT(window == g.NavWindow);
 
@@ -13594,8 +14313,10 @@
             ref_rect.Translate(window->Scroll - next_scroll);
         }
         ImVec2 pos = ImVec2(ref_rect.Min.x + ImMin(g.Style.FramePadding.x * 4, ref_rect.GetWidth()), ref_rect.Max.y - ImMin(g.Style.FramePadding.y, ref_rect.GetHeight()));
-        ImGuiViewport* viewport = GetMainViewport();
-        return ImTrunc(ImClamp(pos, viewport->Pos, viewport->Pos + viewport->Size)); // ImTrunc() is important because non-integer mouse position application in backend might be lossy and result in undesirable non-zero delta.
+        if (window != NULL)
+            if (ImGuiViewport* viewport = window->Viewport)
+                pos = ImClamp(pos, viewport->Pos, viewport->Pos + viewport->Size);
+        return ImTrunc(pos); // ImTrunc() is important because non-integer mouse position application in backend might be lossy and result in undesirable non-zero delta.
     }
 }
 
@@ -14365,16 +15086,19 @@
 // Apply focus and close overlay
 static void ImGui::NavUpdateWindowingApplyFocus(ImGuiWindow* apply_focus_window)
 {
+    // FIXME: Many actions here could be part of a higher-level/reused function. Why aren't they in FocusWindow() ?
+    // Investigate for each of them: ClearActiveID(), NavRestoreHighlightAfterMove(), NavRestoreLastChildNavWindow(), ClosePopupsOverWindow(), NavInitWindow()
     ImGuiContext& g = *GImGui;
     if (g.NavWindow == NULL || apply_focus_window != g.NavWindow->RootWindow)
     {
+        ImGuiViewport* previous_viewport = g.NavWindow ? g.NavWindow->Viewport : NULL;
         ClearActiveID();
         SetNavCursorVisibleAfterMove();
         ClosePopupsOverWindow(apply_focus_window, false);
         FocusWindow(apply_focus_window, ImGuiFocusRequestFlags_RestoreFocusedChild);
         IM_ASSERT(g.NavWindow != NULL);
         apply_focus_window = g.NavWindow;
-        if (apply_focus_window->NavLastIds[0] == 0)
+        if (apply_focus_window->NavLastIds[0] == 0) // FIXME: This is the equivalent of the 'if (g.NavId == 0) { NavInitWindow() }' in DockNodeUpdateTabBar().
             NavInitWindow(apply_focus_window, false);
 
         // If the window has ONLY a menu layer (no main layer), select it directly
@@ -14386,6 +15110,10 @@
         // won't be valid.
         if (apply_focus_window->DC.NavLayersActiveMaskNext == (1 << ImGuiNavLayer_Menu))
             g.NavLayer = ImGuiNavLayer_Menu;
+
+        // Request OS level focus
+        if (apply_focus_window->Viewport != previous_viewport && g.PlatformIO.Platform_SetWindowFocus)
+            g.PlatformIO.Platform_SetWindowFocus(apply_focus_window->Viewport);
     }
     g.NavWindowingTarget = NULL;
 }
@@ -14546,7 +15274,7 @@
             ImVec2 accum_floored = ImTrunc(g.NavWindowingAccumDeltaPos);
             if (accum_floored.x != 0.0f || accum_floored.y != 0.0f)
             {
-                ImGuiWindow* moving_window = g.NavWindowingTarget->RootWindow;
+                ImGuiWindow* moving_window = g.NavWindowingTarget->RootWindowDockTree;
                 SetWindowPos(moving_window, moving_window->Pos + accum_floored, ImGuiCond_Always);
                 g.NavWindowingAccumDeltaPos -= accum_floored;
             }
@@ -14581,7 +15309,8 @@
         if (new_nav_layer != g.NavLayer)
         {
             // Reinitialize navigation when entering menu bar with the Alt key (FIXME: could be a properly of the layer?)
-            if (new_nav_layer == ImGuiNavLayer_Menu)
+            const bool preserve_layer_1_nav_id = (new_nav_window->DockNodeAsHost != NULL);
+            if (new_nav_layer == ImGuiNavLayer_Menu && !preserve_layer_1_nav_id)
                 g.NavWindow->NavLastIds[new_nav_layer] = 0;
             NavRestoreLayer(new_nav_layer);
             SetNavCursorVisibleAfterMove();
@@ -14596,6 +15325,8 @@
         return ImGui::LocalizeGetMsg(ImGuiLocKey_WindowingPopup);
     if ((window->Flags & ImGuiWindowFlags_MenuBar) && strcmp(window->Name, "##MainMenuBar") == 0)
         return ImGui::LocalizeGetMsg(ImGuiLocKey_WindowingMainMenuBar);
+    if (window->DockNodeAsHost)
+        return "(Dock node)"; // Not normally shown to user.
     return ImGui::LocalizeGetMsg(ImGuiLocKey_WindowingUntitled);
 }
 
@@ -14608,7 +15339,7 @@
     if (g.NavWindowingTimer < NAV_WINDOWING_LIST_APPEAR_DELAY)
         return;
 
-    const ImGuiViewport* viewport = GetMainViewport();
+    const ImGuiViewport* viewport = /*g.NavWindow ? g.NavWindow->Viewport :*/ GetMainViewport();
     SetNextWindowSizeConstraints(ImVec2(viewport->Size.x * 0.20f, viewport->Size.y * 0.20f), ImVec2(FLT_MAX, FLT_MAX));
     SetNextWindowPos(viewport->GetCenter(), ImGuiCond_Always, ImVec2(0.5f, 0.5f));
     PushStyleVar(ImGuiStyleVar_WindowPadding, g.Style.WindowPadding * 2.0f);
@@ -14859,7 +15590,7 @@
 
     ImGuiWindow* window = g.CurrentWindow;
     ImGuiWindow* hovered_window = g.HoveredWindowUnderMovingWindow;
-    if (hovered_window == NULL || window->RootWindow != hovered_window->RootWindow)
+    if (hovered_window == NULL || window->RootWindowDockTree != hovered_window->RootWindowDockTree)
         return false;
     IM_ASSERT(id != 0);
     if (!IsMouseHoveringRect(bb.Min, bb.Max) || (id == g.DragDropPayload.SourceId))
@@ -14888,7 +15619,7 @@
 
     ImRect bb = p_bb ? *p_bb : ((ImGuiViewportP*)viewport)->GetWorkRect();
     ImGuiID id = viewport->ID;
-    if (!IsMouseHoveringRect(bb.Min, bb.Max, false) || (id == g.DragDropPayload.SourceId))
+    if (g.MouseViewport != viewport || !IsMouseHoveringRect(bb.Min, bb.Max, false) || (id == g.DragDropPayload.SourceId))
         return false;
 
     IM_ASSERT(g.DragDropWithinTarget == false && g.DragDropWithinSource == false); // Can't nest BeginDragDropSource() and BeginDragDropTarget()
@@ -14914,7 +15645,7 @@
     if (!(g.LastItemData.StatusFlags & ImGuiItemStatusFlags_HoveredRect))
         return false;
     ImGuiWindow* hovered_window = g.HoveredWindowUnderMovingWindow;
-    if (hovered_window == NULL || window->RootWindow != hovered_window->RootWindow || window->SkipItems)
+    if (hovered_window == NULL || window->RootWindowDockTree != hovered_window->RootWindowDockTree || window->SkipItems)
         return false;
 
     const ImRect& display_rect = (g.LastItemData.StatusFlags & ImGuiItemStatusFlags_HasDisplayRect) ? g.LastItemData.DisplayRect : g.LastItemData.Rect;
@@ -14969,9 +15700,11 @@
     const bool draw_target_rect = payload.Preview && !(flags & ImGuiDragDropFlags_AcceptNoDrawDefaultRect);
     if (draw_target_rect && g.DragDropTargetFullViewport != 0)
     {
+        ImGuiViewport* viewport = FindViewportByID(g.DragDropTargetFullViewport);
+        IM_ASSERT(viewport != NULL);
         ImRect bb = g.DragDropTargetRect;
         bb.Expand(-3.5f);
-        RenderDragDropTargetRectEx(GetForegroundDrawList(), bb);
+        RenderDragDropTargetRectEx(GetForegroundDrawList(viewport), bb);
     }
     else if (draw_target_rect)
     {
@@ -15532,11 +16265,14 @@
 void ImGui::ClearWindowSettings(const char* name)
 {
     //IMGUI_DEBUG_LOG("ClearWindowSettings('%s')\n", name);
+    ImGuiContext& g = *GImGui;
     ImGuiWindow* window = FindWindowByName(name);
     if (window != NULL)
     {
         window->Flags |= ImGuiWindowFlags_NoSavedSettings;
         InitOrLoadWindowSettings(window, NULL);
+        if (window->DockId != 0)
+            DockContextProcessUndockWindow(&g, window, true);
     }
     if (ImGuiWindowSettings* settings = window ? FindWindowSettingsByWindow(window) : FindWindowSettingsByID(ImHashStr(name)))
         settings->WantDelete = true;
@@ -15568,10 +16304,16 @@
     ImGuiWindowSettings* settings = (ImGuiWindowSettings*)entry;
     int x, y;
     int i;
-    if (sscanf(line, "Pos=%i,%i", &x, &y) == 2)         { settings->Pos = ImVec2ih((short)x, (short)y); }
-    else if (sscanf(line, "Size=%i,%i", &x, &y) == 2)   { settings->Size = ImVec2ih((short)x, (short)y); }
-    else if (sscanf(line, "Collapsed=%d", &i) == 1)     { settings->Collapsed = (i != 0); }
-    else if (sscanf(line, "IsChild=%d", &i) == 1)       { settings->IsChild = (i != 0); }
+    ImU32 u1;
+    if (sscanf(line, "Pos=%i,%i", &x, &y) == 2)             { settings->Pos = ImVec2ih((short)x, (short)y); }
+    else if (sscanf(line, "Size=%i,%i", &x, &y) == 2)       { settings->Size = ImVec2ih((short)x, (short)y); }
+    else if (sscanf(line, "ViewportId=0x%08X", &u1) == 1)   { settings->ViewportId = u1; }
+    else if (sscanf(line, "ViewportPos=%i,%i", &x, &y) == 2){ settings->ViewportPos = ImVec2ih((short)x, (short)y); }
+    else if (sscanf(line, "Collapsed=%d", &i) == 1)         { settings->Collapsed = (i != 0); }
+    else if (sscanf(line, "IsChild=%d", &i) == 1)           { settings->IsChild = (i != 0); }
+    else if (sscanf(line, "DockId=0x%X,%d", &u1, &i) == 2)  { settings->DockId = u1; settings->DockOrder = (short)i; }
+    else if (sscanf(line, "DockId=0x%X", &u1) == 1)         { settings->DockId = u1; settings->DockOrder = -1; }
+    else if (sscanf(line, "ClassId=0x%X", &u1) == 1)        { settings->ClassId = u1; }
 }
 
 // Apply to existing windows (if any)
@@ -15604,10 +16346,16 @@
             window->SettingsOffset = g.SettingsWindows.offset_from_ptr(settings);
         }
         IM_ASSERT(settings->ID == window->ID);
-        settings->Pos = ImVec2ih(window->Pos);
+        settings->Pos = ImVec2ih(window->Pos - window->ViewportPos);
         settings->Size = ImVec2ih(window->SizeFull);
-        settings->IsChild = (window->Flags & ImGuiWindowFlags_ChildWindow) != 0;
+        settings->ViewportId = window->ViewportId;
+        settings->ViewportPos = ImVec2ih(window->ViewportPos);
+        IM_ASSERT(window->DockNode == NULL || window->DockNode->ID == window->DockId);
+        settings->DockId = window->DockId;
+        settings->ClassId = window->WindowClass.ClassId;
+        settings->DockOrder = window->DockOrder;
         settings->Collapsed = window->Collapsed;
+        settings->IsChild = (window->RootWindow != window); // Cannot rely on ImGuiWindowFlags_ChildWindow here as docked windows have this set.
         settings->WantDelete = false;
     }
 
@@ -15626,10 +16374,26 @@
         }
         else
         {
-            buf->appendf("Pos=%d,%d\n", settings->Pos.x, settings->Pos.y);
-            buf->appendf("Size=%d,%d\n", settings->Size.x, settings->Size.y);
-            if (settings->Collapsed)
-                buf->appendf("Collapsed=1\n");
+            if (settings->ViewportId != 0 && settings->ViewportId != ImGui::IMGUI_VIEWPORT_DEFAULT_ID)
+            {
+                buf->appendf("ViewportPos=%d,%d\n", settings->ViewportPos.x, settings->ViewportPos.y);
+                buf->appendf("ViewportId=0x%08X\n", settings->ViewportId);
+            }
+            if (settings->Pos.x != 0 || settings->Pos.y != 0 || settings->ViewportId == ImGui::IMGUI_VIEWPORT_DEFAULT_ID)
+                buf->appendf("Pos=%d,%d\n", settings->Pos.x, settings->Pos.y);
+            if (settings->Size.x != 0 || settings->Size.y != 0)
+                buf->appendf("Size=%d,%d\n", settings->Size.x, settings->Size.y);
+            buf->appendf("Collapsed=%d\n", settings->Collapsed);
+            if (settings->DockId != 0)
+            {
+                //buf->appendf("TabId=0x%08X\n", ImHashStr("#TAB", 4, settings->ID)); // window->TabId: this is not read back but writing it makes "debugging" the .ini data easier.
+                if (settings->DockOrder == -1)
+                    buf->appendf("DockId=0x%08X\n", settings->DockId);
+                else
+                    buf->appendf("DockId=0x%08X,%d\n", settings->DockId, settings->DockOrder);
+                if (settings->ClassId != 0)
+                    buf->appendf("ClassId=0x%08X\n", settings->ClassId);
+            }
         }
         buf->append("\n");
     }
@@ -15650,27 +16414,59 @@
 // [SECTION] VIEWPORTS, PLATFORM WINDOWS
 //-----------------------------------------------------------------------------
 // - GetMainViewport()
+// - FindViewportByID()
+// - FindViewportByPlatformHandle()
+// - SetCurrentViewport() [Internal]
 // - SetWindowViewport() [Internal]
+// - GetWindowAlwaysWantOwnViewport() [Internal]
+// - UpdateTryMergeWindowIntoHostViewport() [Internal]
+// - UpdateTryMergeWindowIntoHostViewports() [Internal]
+// - TranslateWindowsInViewport() [Internal]
 // - ScaleWindowsInViewport() [Internal]
+// - FindHoveredViewportFromPlatformWindowStack() [Internal]
 // - UpdateViewportsNewFrame() [Internal]
-// (this section is more complete in the 'docking' branch)
+// - UpdateViewportsEndFrame() [Internal]
+// - AddUpdateViewport() [Internal]
+// - WindowSelectViewport() [Internal]
+// - WindowSyncOwnedViewport() [Internal]
+// - UpdatePlatformWindows()
+// - RenderPlatformWindowsDefault()
+// - FindPlatformMonitorForPos() [Internal]
+// - FindPlatformMonitorForRect() [Internal]
+// - UpdateViewportPlatformMonitor() [Internal]
+// - DestroyPlatformWindow() [Internal]
+// - DestroyPlatformWindows()
 //-----------------------------------------------------------------------------
 
 void ImGuiPlatformIO::ClearPlatformHandlers()
 {
     Platform_GetClipboardTextFn = NULL;
     Platform_SetClipboardTextFn = NULL;
-    Platform_ClipboardUserData = NULL;
     Platform_OpenInShellFn = NULL;
-    Platform_OpenInShellUserData = NULL;
     Platform_SetImeDataFn = NULL;
-    Platform_ImeUserData = NULL;
+    Platform_ClipboardUserData = Platform_OpenInShellUserData = Platform_ImeUserData = NULL;
+    Platform_CreateWindow = Platform_DestroyWindow = Platform_ShowWindow = NULL;
+    Platform_SetWindowPos = Platform_SetWindowSize = NULL;
+    Platform_GetWindowPos = Platform_GetWindowSize = Platform_GetWindowFramebufferScale = NULL;
+    Platform_SetWindowFocus = NULL;
+    Platform_GetWindowFocus = Platform_GetWindowMinimized = NULL;
+    Platform_SetWindowTitle = NULL;
+    Platform_SetWindowAlpha = NULL;
+    Platform_UpdateWindow = NULL;
+    Platform_RenderWindow = Platform_SwapBuffers = NULL;
+    Platform_GetWindowDpiScale = NULL;
+    Platform_OnChangedViewport = NULL;
+    Platform_GetWindowWorkAreaInsets = NULL;
+    Platform_CreateVkSurface = NULL;
 }
 
 void ImGuiPlatformIO::ClearRendererHandlers()
 {
     Renderer_TextureMaxWidth = Renderer_TextureMaxHeight = 0;
     Renderer_RenderState = NULL;
+    Renderer_CreateWindow = Renderer_DestroyWindow = NULL;
+    Renderer_SetWindowSize = NULL;
+    Renderer_RenderWindow = Renderer_SwapBuffers = NULL;
 }
 
 ImGuiViewport* ImGui::GetMainViewport()
@@ -15679,60 +16475,5009 @@
     return g.Viewports[0];
 }
 
-void ImGui::SetWindowViewport(ImGuiWindow* window, ImGuiViewportP* viewport)
+// FIXME: This leaks access to viewports not listed in PlatformIO.Viewports[]. Problematic? (#4236)
+ImGuiViewport* ImGui::FindViewportByID(ImGuiID viewport_id)
 {
-    window->Viewport = viewport;
+    ImGuiContext& g = *GImGui;
+    for (ImGuiViewportP* viewport : g.Viewports)
+        if (viewport->ID == viewport_id)
+            return viewport;
+    return NULL;
 }
 
-static void ScaleWindow(ImGuiWindow* window, float scale)
+ImGuiViewport* ImGui::FindViewportByPlatformHandle(void* platform_handle)
 {
-    ImVec2 origin = window->Viewport->Pos;
-    window->Pos = ImFloor((window->Pos - origin) * scale + origin);
-    window->Size = ImTrunc(window->Size * scale);
-    window->SizeFull = ImTrunc(window->SizeFull * scale);
-    window->ContentSize = ImTrunc(window->ContentSize * scale);
+    ImGuiContext& g = *GImGui;
+    for (ImGuiViewportP* viewport : g.Viewports)
+        if (viewport->PlatformHandle == platform_handle)
+            return viewport;
+    return NULL;
+}
+
+void ImGui::SetCurrentViewport(ImGuiWindow* current_window, ImGuiViewportP* viewport)
+{
+    ImGuiContext& g = *GImGui;
+    (void)current_window;
+
+    if (viewport)
+        viewport->LastFrameActive = g.FrameCount;
+    if (g.CurrentViewport == viewport)
+        return;
+    g.CurrentDpiScale = viewport ? viewport->DpiScale : 1.0f;
+    g.CurrentViewport = viewport;
+    IM_ASSERT(g.CurrentDpiScale > 0.0f && g.CurrentDpiScale < 99.0f); // Typical correct values would be between 1.0f and 4.0f
+    //IMGUI_DEBUG_LOG_VIEWPORT("[viewport] SetCurrentViewport changed '%s' 0x%08X\n", current_window ? current_window->Name : NULL, viewport ? viewport->ID : 0);
+    if (g.IO.ConfigDpiScaleFonts)
+        g.Style.FontScaleDpi = g.CurrentDpiScale;
+
+    // Notify platform layer of viewport changes
+    // FIXME-DPI: This is only currently used for experimenting with handling of multiple DPI
+    if (g.CurrentViewport && g.PlatformIO.Platform_OnChangedViewport)
+        g.PlatformIO.Platform_OnChangedViewport(g.CurrentViewport);
+}
+
+void ImGui::SetWindowViewport(ImGuiWindow* window, ImGuiViewportP* viewport)
+{
+    // Abandon viewport
+    if (window->ViewportOwned && window->Viewport->Window == window)
+        window->Viewport->Size = ImVec2(0.0f, 0.0f);
+
+    window->Viewport = viewport;
+    window->ViewportId = viewport->ID;
+    window->ViewportOwned = (viewport->Window == window);
+}
+
+static bool ImGui::GetWindowAlwaysWantOwnViewport(ImGuiWindow* window)
+{
+    // Tooltips and menus are not automatically forced into their own viewport when the NoMerge flag is set, however the multiplication of viewports makes them more likely to protrude and create their own.
+    ImGuiContext& g = *GImGui;
+    if (g.IO.ConfigViewportsNoAutoMerge || (window->WindowClass.ViewportFlagsOverrideSet & ImGuiViewportFlags_NoAutoMerge))
+        if (g.ConfigFlagsCurrFrame & ImGuiConfigFlags_ViewportsEnable)
+            if (!window->DockIsActive)
+                if ((window->Flags & (ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_ChildMenu | ImGuiWindowFlags_Tooltip)) == 0)
+                    if ((window->Flags & ImGuiWindowFlags_Popup) == 0 || (window->Flags & ImGuiWindowFlags_Modal) != 0)
+                        return true;
+    return false;
+}
+
+
+// Heuristic, see #8948: depends on how backends handle OS-level parenting.
+// Due to how parent viewport stack is layed out, note that IsViewportAbove(a,b) isn't always the same as !IsViewportAbove(b,a).
+static bool IsViewportAbove(ImGuiViewportP* potential_above, ImGuiViewportP* potential_below)
+{
+    // If ImGuiBackendFlags_HasParentViewport if set, ->ParentViewport chain should be accurate.
+    ImGuiContext& g = *GImGui;
+    if (g.IO.BackendFlags & ImGuiBackendFlags_HasParentViewport)
+    {
+        for (ImGuiViewport* v = potential_above; v != NULL && v->ParentViewport; v = v->ParentViewport)
+            if (v->ParentViewport == potential_below)
+                return true;
+    }
+    else
+    {
+        if (potential_above->ParentViewport == potential_below)
+            return true;
+    }
+
+    if (potential_above->LastFocusedStampCount > potential_below->LastFocusedStampCount)
+        return true;
+    return false;
+}
+
+static bool ImGui::UpdateTryMergeWindowIntoHostViewport(ImGuiWindow* window, ImGuiViewportP* viewport_dst)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(window == window->RootWindowDockTree);
+    ImGuiViewportP* viewport_src = window->Viewport; // Current viewport
+    if (viewport_src == viewport_dst)
+        return false;
+    if ((viewport_dst->Flags & ImGuiViewportFlags_CanHostOtherWindows) == 0)
+        return false;
+    if ((viewport_dst->Flags & ImGuiViewportFlags_IsMinimized) != 0)
+        return false;
+    if (!viewport_dst->GetMainRect().Contains(window->Rect()))
+        return false;
+    if (GetWindowAlwaysWantOwnViewport(window))
+        return false;
+
+    for (ImGuiViewportP* viewport_obstructing : g.Viewports)
+    {
+        if (viewport_obstructing == viewport_src || viewport_obstructing == viewport_dst)
+            continue;
+        if (viewport_obstructing->GetMainRect().Overlaps(window->Rect()))
+            if (IsViewportAbove(viewport_obstructing, viewport_dst))
+                if (viewport_src == NULL || IsViewportAbove(viewport_src, viewport_obstructing))
+                    return false; // viewport_obstructing is between viewport_src and viewport_dst -> Cannot merge.
+    }
+
+    // Move to the existing viewport, Move child/hosted windows as well (FIXME-OPT: iterate child)
+    IMGUI_DEBUG_LOG_VIEWPORT("[viewport] Window '%s' merge into Viewport 0X%08X\n", window->Name, viewport_dst->ID);
+    if (window->ViewportOwned)
+        for (int n = 0; n < g.Windows.Size; n++)
+            if (g.Windows[n]->Viewport == viewport_src)
+                SetWindowViewport(g.Windows[n], viewport_dst);
+    SetWindowViewport(window, viewport_dst);
+    if ((window->Flags & ImGuiWindowFlags_NoBringToFrontOnFocus) == 0)
+        BringWindowToDisplayFront(window);
+
+    return true;
+}
+
+// FIXME: handle 0 to N host viewports
+static bool ImGui::UpdateTryMergeWindowIntoHostViewports(ImGuiWindow* window)
+{
+    ImGuiContext& g = *GImGui;
+    return UpdateTryMergeWindowIntoHostViewport(window, g.Viewports[0]);
+}
+
+// Translate Dear ImGui windows when a Host Viewport has been moved
+// (This additionally keeps windows at the same place when ImGuiConfigFlags_ViewportsEnable is toggled!)
+void ImGui::TranslateWindowsInViewport(ImGuiViewportP* viewport, const ImVec2& old_pos, const ImVec2& new_pos, const ImVec2& old_size, const ImVec2& new_size)
+{
+    ImGuiContext& g = *GImGui;
+    //IMGUI_DEBUG_LOG_VIEWPORT("[viewport] TranslateWindowsInViewport 0x%08X\n", viewport->ID);
+    IM_ASSERT(viewport->Window == NULL && (viewport->Flags & ImGuiViewportFlags_CanHostOtherWindows));
+
+    // 1) We test if ImGuiConfigFlags_ViewportsEnable was just toggled, which allows us to conveniently
+    // translate imgui windows from OS-window-local to absolute coordinates or vice-versa.
+    // 2) If it's not going to fit into the new size, keep it at same absolute position.
+    // One problem with this is that most Win32 applications doesn't update their render while dragging,
+    // and so the window will appear to teleport when releasing the mouse.
+    const bool translate_all_windows = (g.ConfigFlagsCurrFrame & ImGuiConfigFlags_ViewportsEnable) != (g.ConfigFlagsLastFrame & ImGuiConfigFlags_ViewportsEnable);
+    ImRect test_still_fit_rect(old_pos, old_pos + old_size);
+    ImVec2 delta_pos = new_pos - old_pos;
+    for (ImGuiWindow* window : g.Windows) // FIXME-OPT
+        if (translate_all_windows || (window->Viewport == viewport && (old_size == new_size || test_still_fit_rect.Contains(window->Rect()))))
+            TranslateWindow(window, delta_pos);
 }
 
 // Scale all windows (position, size). Use when e.g. changing DPI. (This is a lossy operation!)
 void ImGui::ScaleWindowsInViewport(ImGuiViewportP* viewport, float scale)
 {
     ImGuiContext& g = *GImGui;
-    for (ImGuiWindow* window : g.Windows)
-        if (window->Viewport == viewport)
-            ScaleWindow(window, scale);
+    //IMGUI_DEBUG_LOG_VIEWPORT("[viewport] ScaleWindowsInViewport 0x%08X\n", viewport->ID);
+    if (viewport->Window)
+    {
+        ScaleWindow(viewport->Window, scale);
+    }
+    else
+    {
+        for (ImGuiWindow* window : g.Windows)
+            if (window->Viewport == viewport)
+                ScaleWindow(window, scale);
+    }
+}
+
+// If the backend doesn't set MouseLastHoveredViewport or doesn't honor ImGuiViewportFlags_NoInputs, we do a search ourselves.
+// A) It won't take account of the possibility that non-imgui windows may be in-between our dragged window and our target window.
+// B) It requires Platform_GetWindowFocus to be implemented by backend.
+ImGuiViewportP* ImGui::FindHoveredViewportFromPlatformWindowStack(const ImVec2& mouse_platform_pos)
+{
+    ImGuiContext& g = *GImGui;
+    ImGuiViewportP* best_candidate = NULL;
+    for (ImGuiViewportP* viewport : g.Viewports)
+        if (!(viewport->Flags & (ImGuiViewportFlags_NoInputs | ImGuiViewportFlags_IsMinimized)) && viewport->GetMainRect().Contains(mouse_platform_pos))
+            if (best_candidate == NULL || best_candidate->LastFocusedStampCount < viewport->LastFocusedStampCount)
+                best_candidate = viewport;
+    return best_candidate;
 }
 
 // Update viewports and monitor infos
+// Note that this is running even if 'ImGuiConfigFlags_ViewportsEnable' is not set, in order to clear unused viewports (if any) and update monitor info.
 static void ImGui::UpdateViewportsNewFrame()
 {
     ImGuiContext& g = *GImGui;
-    IM_ASSERT(g.Viewports.Size == 1);
+    IM_ASSERT(g.PlatformIO.Viewports.Size <= g.Viewports.Size);
 
-    // Update main viewport with current platform position.
+    // Update Minimized status (we need it first in order to decide if we'll apply Pos/Size of the main viewport)
+    // Update Focused status
+    const bool viewports_enabled = (g.ConfigFlagsCurrFrame & ImGuiConfigFlags_ViewportsEnable) != 0;
+    if (viewports_enabled)
+    {
+        ImGuiViewportP* focused_viewport = NULL;
+        for (ImGuiViewportP* viewport : g.Viewports)
+        {
+            const bool platform_funcs_available = viewport->PlatformWindowCreated;
+            if (g.PlatformIO.Platform_GetWindowMinimized && platform_funcs_available)
+            {
+                bool is_minimized = g.PlatformIO.Platform_GetWindowMinimized(viewport);
+                if (is_minimized)
+                    viewport->Flags |= ImGuiViewportFlags_IsMinimized;
+                else
+                    viewport->Flags &= ~ImGuiViewportFlags_IsMinimized;
+            }
+
+            // Update our implicit z-order knowledge of platform windows, which is used when the backend cannot provide io.MouseHoveredViewport.
+            // When setting Platform_GetWindowFocus, it is expected that the platform backend can handle calls without crashing if it doesn't have data stored.
+            if (g.PlatformIO.Platform_GetWindowFocus && platform_funcs_available)
+            {
+                bool is_focused = g.PlatformIO.Platform_GetWindowFocus(viewport);
+                if (is_focused)
+                    viewport->Flags |= ImGuiViewportFlags_IsFocused;
+                else
+                    viewport->Flags &= ~ImGuiViewportFlags_IsFocused;
+                if (is_focused)
+                    focused_viewport = viewport;
+            }
+        }
+
+        // Focused viewport has changed?
+        if (focused_viewport && g.PlatformLastFocusedViewportId != focused_viewport->ID)
+        {
+            IMGUI_DEBUG_LOG_VIEWPORT("[viewport] Focused viewport changed %08X -> %08X '%s', attempting to apply our focus.\n", g.PlatformLastFocusedViewportId, focused_viewport->ID, focused_viewport->Window ? focused_viewport->Window->Name : "n/a");
+            const ImGuiViewport* prev_focused_viewport = FindViewportByID(g.PlatformLastFocusedViewportId);
+            const bool prev_focused_has_been_destroyed = (prev_focused_viewport == NULL) || (prev_focused_viewport->PlatformWindowCreated == false);
+
+            // Store a tag so we can infer z-order easily from all our windows
+            // We compare PlatformLastFocusedViewportId so newly created viewports with _NoFocusOnAppearing flag
+            // will keep the front most stamp instead of losing it back to their parent viewport.
+            if (focused_viewport->LastFocusedStampCount != g.ViewportFocusedStampCount)
+                focused_viewport->LastFocusedStampCount = ++g.ViewportFocusedStampCount;
+            g.PlatformLastFocusedViewportId = focused_viewport->ID;
+
+            // Focus associated dear imgui window
+            // - if focus didn't happen with a click within imgui boundaries, e.g. Clicking platform title bar. (#6299)
+            // - if focus didn't happen because we destroyed another window (#6462)
+            // FIXME: perhaps 'FocusTopMostWindowUnderOne()' can handle the 'focused_window->Window != NULL' case as well.
+            const bool apply_imgui_focus_on_focused_viewport = !IsAnyMouseDown() && !prev_focused_has_been_destroyed;
+            if (apply_imgui_focus_on_focused_viewport && g.IO.ConfigViewportsPlatformFocusSetsImGuiFocus)
+            {
+                focused_viewport->LastFocusedHadNavWindow |= (g.NavWindow != NULL) && (g.NavWindow->Viewport == focused_viewport); // Update so a window changing viewport won't lose focus.
+                ImGuiFocusRequestFlags focus_request_flags = ImGuiFocusRequestFlags_UnlessBelowModal | ImGuiFocusRequestFlags_RestoreFocusedChild;
+                if (focused_viewport->Window != NULL)
+                    FocusWindow(focused_viewport->Window, focus_request_flags);
+                else if (focused_viewport->LastFocusedHadNavWindow)
+                    FocusTopMostWindowUnderOne(NULL, NULL, focused_viewport, focus_request_flags); // Focus top most in viewport
+                else
+                    FocusWindow(NULL, focus_request_flags); // No window had focus last time viewport was focused
+            }
+        }
+        if (focused_viewport)
+            focused_viewport->LastFocusedHadNavWindow = (g.NavWindow != NULL) && (g.NavWindow->Viewport == focused_viewport);
+    }
+
+    // Create/update main viewport with current platform position.
     // FIXME-VIEWPORT: Size is driven by backend/user code for backward-compatibility but we should aim to make this more consistent.
     ImGuiViewportP* main_viewport = g.Viewports[0];
-    main_viewport->Flags = ImGuiViewportFlags_IsPlatformWindow | ImGuiViewportFlags_OwnedByApp;
-    main_viewport->Pos = ImVec2(0.0f, 0.0f);
-    main_viewport->Size = g.IO.DisplaySize;
-    main_viewport->FramebufferScale = g.IO.DisplayFramebufferScale;
-    IM_ASSERT(main_viewport->FramebufferScale.x > 0.0f && main_viewport->FramebufferScale.y > 0.0f);
-
-    for (ImGuiViewportP* viewport : g.Viewports)
+    IM_ASSERT(main_viewport->ID == IMGUI_VIEWPORT_DEFAULT_ID);
+    IM_ASSERT(main_viewport->Window == NULL);
+    ImVec2 main_viewport_pos = viewports_enabled ? g.PlatformIO.Platform_GetWindowPos(main_viewport) : ImVec2(0.0f, 0.0f);
+    ImVec2 main_viewport_size = g.IO.DisplaySize;
+    ImVec2 main_viewport_framebuffer_scale = g.IO.DisplayFramebufferScale;
+    if (viewports_enabled && (main_viewport->Flags & ImGuiViewportFlags_IsMinimized))
     {
-        // Lock down space taken by menu bars and status bars
+        main_viewport_pos = main_viewport->Pos; // Preserve last pos/size when minimized (FIXME: We don't do the same for Size outside of the viewport path)
+        main_viewport_size = main_viewport->Size;
+        main_viewport_framebuffer_scale = main_viewport->FramebufferScale;
+    }
+    AddUpdateViewport(NULL, IMGUI_VIEWPORT_DEFAULT_ID, main_viewport_pos, main_viewport_size, ImGuiViewportFlags_OwnedByApp | ImGuiViewportFlags_CanHostOtherWindows);
+
+    g.CurrentDpiScale = 0.0f;
+    g.CurrentViewport = NULL;
+    g.MouseViewport = NULL;
+    for (int n = 0; n < g.Viewports.Size; n++)
+    {
+        ImGuiViewportP* viewport = g.Viewports[n];
+        viewport->Idx = n;
+
+        // Erase unused viewports
+        if (n > 0 && viewport->LastFrameActive < g.FrameCount - 2)
+        {
+            DestroyViewport(viewport);
+            n--;
+            continue;
+        }
+
+        const bool platform_funcs_available = viewport->PlatformWindowCreated;
+        if (viewports_enabled)
+        {
+            // Update Position and Size (from Platform Window to ImGui) if requested.
+            // We do it early in the frame instead of waiting for UpdatePlatformWindows() to avoid a frame of lag when moving/resizing using OS facilities.
+            if (!(viewport->Flags & ImGuiViewportFlags_IsMinimized) && platform_funcs_available)
+            {
+                // Viewport->WorkPos and WorkSize will be updated below
+                if (viewport->PlatformRequestMove)
+                    viewport->Pos = viewport->LastPlatformPos = g.PlatformIO.Platform_GetWindowPos(viewport);
+                if (viewport->PlatformRequestResize)
+                    viewport->Size = viewport->LastPlatformSize = g.PlatformIO.Platform_GetWindowSize(viewport);
+                if (g.PlatformIO.Platform_GetWindowFramebufferScale != NULL)
+                    viewport->FramebufferScale = g.PlatformIO.Platform_GetWindowFramebufferScale(viewport);
+            }
+        }
+
+        // Update/copy monitor info
+        UpdateViewportPlatformMonitor(viewport);
+
+        // Lock down space taken by menu bars and status bars + query initial insets from backend
         // Setup initial value for functions like BeginMainMenuBar(), DockSpaceOverViewport() etc.
         viewport->WorkInsetMin = viewport->BuildWorkInsetMin;
         viewport->WorkInsetMax = viewport->BuildWorkInsetMax;
         viewport->BuildWorkInsetMin = viewport->BuildWorkInsetMax = ImVec2(0.0f, 0.0f);
+        if (g.PlatformIO.Platform_GetWindowWorkAreaInsets != NULL && platform_funcs_available)
+        {
+            ImVec4 insets = g.PlatformIO.Platform_GetWindowWorkAreaInsets(viewport);
+            IM_ASSERT(insets.x >= 0.0f && insets.y >= 0.0f && insets.z >= 0.0f && insets.w >= 0.0f);
+            viewport->BuildWorkInsetMin = ImVec2(insets.x, insets.y);
+            viewport->BuildWorkInsetMax = ImVec2(insets.z, insets.w);
+        }
         viewport->UpdateWorkRect();
+
+        // Reset alpha every frame. Users of transparency (docking) needs to request a lower alpha back.
+        viewport->Alpha = 1.0f;
+
+        // Translate Dear ImGui windows when a Host Viewport has been moved
+        // (This additionally keeps windows at the same place when ImGuiConfigFlags_ViewportsEnable is toggled!)
+        const ImVec2 viewport_delta_pos = viewport->Pos - viewport->LastPos;
+        if ((viewport->Flags & ImGuiViewportFlags_CanHostOtherWindows) && (viewport_delta_pos.x != 0.0f || viewport_delta_pos.y != 0.0f))
+            TranslateWindowsInViewport(viewport, viewport->LastPos, viewport->Pos, viewport->LastSize, viewport->Size);
+
+        // Update DPI scale
+        float new_dpi_scale;
+        if (g.PlatformIO.Platform_GetWindowDpiScale && platform_funcs_available)
+            new_dpi_scale = g.PlatformIO.Platform_GetWindowDpiScale(viewport);
+        else if (viewport->PlatformMonitor != -1)
+            new_dpi_scale = g.PlatformIO.Monitors[viewport->PlatformMonitor].DpiScale;
+        else
+            new_dpi_scale = (viewport->DpiScale != 0.0f) ? viewport->DpiScale : 1.0f;
+        IM_ASSERT(new_dpi_scale > 0.0f && new_dpi_scale < 99.0f); // Typical correct values would be between 1.0f and 4.0f
+        if (viewport->DpiScale != 0.0f && new_dpi_scale != viewport->DpiScale)
+        {
+            float scale_factor = new_dpi_scale / viewport->DpiScale;
+            if (g.IO.ConfigDpiScaleViewports)
+                ScaleWindowsInViewport(viewport, scale_factor);
+            //if (viewport == GetMainViewport())
+            //    g.PlatformInterface.SetWindowSize(viewport, viewport->Size * scale_factor);
+
+            // Scale our window moving pivot so that the window will rescale roughly around the mouse position.
+            // FIXME-VIEWPORT: This currently creates a resizing feedback loop when a window is straddling a DPI transition border.
+            // (Minor: since our sizes do not perfectly linearly scale, deferring the click offset scale until we know the actual window scale ratio may get us slightly more precise mouse positioning.)
+            //if (g.MovingWindow != NULL && g.MovingWindow->Viewport == viewport)
+            //    g.ActiveIdClickOffset = ImTrunc(g.ActiveIdClickOffset * scale_factor);
+        }
+        viewport->DpiScale = new_dpi_scale;
+    }
+
+    // Update fallback monitor
+    g.PlatformMonitorsFullWorkRect = ImRect(+FLT_MAX, +FLT_MAX, -FLT_MAX, -FLT_MAX);
+    if (g.PlatformIO.Monitors.Size == 0)
+    {
+        ImGuiPlatformMonitor* monitor = &g.FallbackMonitor;
+        monitor->MainPos = main_viewport->Pos;
+        monitor->MainSize = main_viewport->Size;
+        monitor->WorkPos = main_viewport->WorkPos;
+        monitor->WorkSize = main_viewport->WorkSize;
+        monitor->DpiScale = main_viewport->DpiScale;
+        g.PlatformMonitorsFullWorkRect.Add(monitor->WorkPos);
+        g.PlatformMonitorsFullWorkRect.Add(monitor->WorkPos + monitor->WorkSize);
+    }
+    else
+    {
+        g.FallbackMonitor = g.PlatformIO.Monitors[0];
+    }
+    for (ImGuiPlatformMonitor& monitor : g.PlatformIO.Monitors)
+    {
+        g.PlatformMonitorsFullWorkRect.Add(monitor.WorkPos);
+        g.PlatformMonitorsFullWorkRect.Add(monitor.WorkPos + monitor.WorkSize);
+    }
+
+    if (!viewports_enabled)
+    {
+        g.MouseViewport = main_viewport;
+        return;
+    }
+
+    // Mouse handling: decide on the actual mouse viewport for this frame between the active/focused viewport and the hovered viewport.
+    // Note that 'viewport_hovered' should skip over any viewport that has the ImGuiViewportFlags_NoInputs flags set.
+    ImGuiViewportP* viewport_hovered = NULL;
+    if (g.IO.BackendFlags & ImGuiBackendFlags_HasMouseHoveredViewport)
+    {
+        viewport_hovered = g.IO.MouseHoveredViewport ? (ImGuiViewportP*)FindViewportByID(g.IO.MouseHoveredViewport) : NULL;
+        if (viewport_hovered && (viewport_hovered->Flags & ImGuiViewportFlags_NoInputs))
+            viewport_hovered = FindHoveredViewportFromPlatformWindowStack(g.IO.MousePos); // Backend failed to handle _NoInputs viewport: revert to our fallback.
+    }
+    else
+    {
+        // If the backend doesn't know how to honor ImGuiViewportFlags_NoInputs, we do a search ourselves. Note that this search:
+        // A) won't take account of the possibility that non-imgui windows may be in-between our dragged window and our target window.
+        // B) won't take account of how the backend apply parent<>child relationship to secondary viewports, which affects their Z order.
+        // C) uses LastFrameAsRefViewport as a flawed replacement for the last time a window was focused (we could/should fix that by introducing Focus functions in PlatformIO)
+        viewport_hovered = FindHoveredViewportFromPlatformWindowStack(g.IO.MousePos);
+    }
+    if (viewport_hovered != NULL)
+        g.MouseLastHoveredViewport = viewport_hovered;
+    else if (g.MouseLastHoveredViewport == NULL)
+        g.MouseLastHoveredViewport = g.Viewports[0];
+
+    // Update mouse reference viewport
+    // (when moving a window we aim at its viewport, but this will be overwritten below if we go in drag and drop mode)
+    // (MovingViewport->Viewport will be NULL in the rare situation where the window disappared while moving, set UpdateMouseMovingWindowNewFrame() for details)
+    if (g.MovingWindow && g.MovingWindow->Viewport)
+        g.MouseViewport = g.MovingWindow->Viewport;
+    else
+        g.MouseViewport = g.MouseLastHoveredViewport;
+
+    // When dragging something, always refer to the last hovered viewport.
+    // - when releasing a moving window we will revert to aiming behind (at viewport_hovered)
+    // - when we are between viewports, our dragged preview will tend to show in the last viewport _even_ if we don't have tooltips in their viewports (when lacking monitor info)
+    // - consider the case of holding on a menu item to browse child menus: even thou a mouse button is held, there's no active id because menu items only react on mouse release.
+    // FIXME-VIEWPORT: This is essentially broken, when ImGuiBackendFlags_HasMouseHoveredViewport is set we want to trust when viewport_hovered==NULL and use that.
+    const bool is_mouse_dragging_with_an_expected_destination = g.DragDropActive;
+    if (is_mouse_dragging_with_an_expected_destination && viewport_hovered == NULL)
+        viewport_hovered = g.MouseLastHoveredViewport;
+    if (is_mouse_dragging_with_an_expected_destination || g.ActiveId == 0 || !IsAnyMouseDown())
+        if (viewport_hovered != NULL && viewport_hovered != g.MouseViewport && !(viewport_hovered->Flags & ImGuiViewportFlags_NoInputs))
+            g.MouseViewport = viewport_hovered;
+
+    IM_ASSERT(g.MouseViewport != NULL);
+}
+
+// Update user-facing viewport list (g.Viewports -> g.PlatformIO.Viewports after filtering out some)
+static void ImGui::UpdateViewportsEndFrame()
+{
+    ImGuiContext& g = *GImGui;
+    g.PlatformIO.Viewports.resize(0);
+    for (int i = 0; i < g.Viewports.Size; i++)
+    {
+        ImGuiViewportP* viewport = g.Viewports[i];
+        viewport->LastPos = viewport->Pos;
+        viewport->LastSize = viewport->Size;
+        if (viewport->LastFrameActive < g.FrameCount || viewport->Size.x <= 0.0f || viewport->Size.y <= 0.0f)
+            if (i > 0) // Always include main viewport in the list
+                continue;
+        if (viewport->Window && !IsWindowActiveAndVisible(viewport->Window))
+            continue;
+        if (i > 0)
+            IM_ASSERT(viewport->Window != NULL);
+        g.PlatformIO.Viewports.push_back(viewport);
+    }
+    g.Viewports[0]->ClearRequestFlags(); // Clear main viewport flags because UpdatePlatformWindows() won't do it and may not even be called
+}
+
+// FIXME: We should ideally refactor the system to call this every frame (we currently don't)
+ImGuiViewportP* ImGui::AddUpdateViewport(ImGuiWindow* window, ImGuiID id, const ImVec2& pos, const ImVec2& size, ImGuiViewportFlags flags)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(id != 0);
+
+    flags |= ImGuiViewportFlags_IsPlatformWindow;
+    if (window != NULL)
+    {
+        const bool window_can_use_inputs = ((window->Flags & ImGuiWindowFlags_NoMouseInputs) && (window->Flags & ImGuiWindowFlags_NoNavInputs)) == false;
+        if (g.MovingWindow && g.MovingWindow->RootWindowDockTree == window)
+            flags |= ImGuiViewportFlags_NoInputs | ImGuiViewportFlags_NoFocusOnAppearing;
+        if (!window_can_use_inputs)
+            flags |= ImGuiViewportFlags_NoInputs;
+        if (window->Flags & ImGuiWindowFlags_NoFocusOnAppearing)
+            flags |= ImGuiViewportFlags_NoFocusOnAppearing;
+    }
+
+    ImGuiViewportP* viewport = (ImGuiViewportP*)FindViewportByID(id);
+    if (viewport)
+    {
+        // Always update for main viewport as we are already pulling correct platform pos/size (see #4900)
+        ImVec2 prev_pos = viewport->Pos;
+        ImVec2 prev_size = viewport->Size;
+        if (!viewport->PlatformRequestMove || viewport->ID == IMGUI_VIEWPORT_DEFAULT_ID)
+            viewport->Pos = pos;
+        if (!viewport->PlatformRequestResize || viewport->ID == IMGUI_VIEWPORT_DEFAULT_ID)
+            viewport->Size = size;
+        viewport->Flags = flags | (viewport->Flags & (ImGuiViewportFlags_IsMinimized | ImGuiViewportFlags_IsFocused)); // Preserve existing flags
+        if (prev_pos != viewport->Pos || prev_size != viewport->Size)
+            UpdateViewportPlatformMonitor(viewport);
+    }
+    else
+    {
+        // New viewport
+        viewport = IM_NEW(ImGuiViewportP)();
+        viewport->ID = id;
+        viewport->Idx = g.Viewports.Size;
+        viewport->Pos = viewport->LastPos = pos;
+        viewport->Size = viewport->LastSize = size;
+        viewport->Flags = flags;
+        UpdateViewportPlatformMonitor(viewport);
+        g.Viewports.push_back(viewport);
+        g.ViewportCreatedCount++;
+        IMGUI_DEBUG_LOG_VIEWPORT("[viewport] Add Viewport %08X '%s'\n", id, window ? window->Name : "<NULL>");
+
+        // We assume the window becomes front-most (even when ImGuiViewportFlags_NoFocusOnAppearing is used).
+        // This is useful for our platform z-order heuristic when io.MouseHoveredViewport is not available.
+        viewport->LastFocusedStampCount = ++g.ViewportFocusedStampCount;
+
+        // We normally setup for all viewports in NewFrame() but here need to handle the mid-frame creation of a new viewport.
+        // We need to extend the fullscreen clip rect so the OverlayDrawList clip is correct for that the first frame
+        g.DrawListSharedData.ClipRectFullscreen.x = ImMin(g.DrawListSharedData.ClipRectFullscreen.x, viewport->Pos.x);
+        g.DrawListSharedData.ClipRectFullscreen.y = ImMin(g.DrawListSharedData.ClipRectFullscreen.y, viewport->Pos.y);
+        g.DrawListSharedData.ClipRectFullscreen.z = ImMax(g.DrawListSharedData.ClipRectFullscreen.z, viewport->Pos.x + viewport->Size.x);
+        g.DrawListSharedData.ClipRectFullscreen.w = ImMax(g.DrawListSharedData.ClipRectFullscreen.w, viewport->Pos.y + viewport->Size.y);
+
+        // Store initial DpiScale before the OS platform window creation, based on expected monitor data.
+        // This is so we can select an appropriate font size on the first frame of our window lifetime
+        viewport->DpiScale = GetViewportPlatformMonitor(viewport)->DpiScale;
+    }
+
+    viewport->Window = window;
+    viewport->LastFrameActive = g.FrameCount;
+    viewport->UpdateWorkRect();
+    IM_ASSERT(window == NULL || viewport->ID == window->ID);
+
+    if (window != NULL)
+        window->ViewportOwned = true;
+
+    return viewport;
+}
+
+static void ImGui::DestroyViewport(ImGuiViewportP* viewport)
+{
+    // Clear references to this viewport in windows (window->ViewportId becomes the master data)
+    ImGuiContext& g = *GImGui;
+    for (ImGuiWindow* window : g.Windows)
+    {
+        if (window->Viewport != viewport)
+            continue;
+        window->Viewport = NULL;
+        window->ViewportOwned = false;
+    }
+    if (viewport == g.MouseLastHoveredViewport)
+        g.MouseLastHoveredViewport = NULL;
+
+    // Destroy
+    IMGUI_DEBUG_LOG_VIEWPORT("[viewport] Delete Viewport %08X '%s'\n", viewport->ID, viewport->Window ? viewport->Window->Name : "n/a");
+    DestroyPlatformWindow(viewport); // In most circumstances the platform window will already be destroyed here.
+    IM_ASSERT(g.PlatformIO.Viewports.contains(viewport) == false);
+    IM_ASSERT(g.Viewports[viewport->Idx] == viewport);
+    g.Viewports.erase(g.Viewports.Data + viewport->Idx);
+    IM_DELETE(viewport);
+}
+
+// FIXME-VIEWPORT: This is all super messy and ought to be clarified or rewritten.
+static void ImGui::WindowSelectViewport(ImGuiWindow* window)
+{
+    ImGuiContext& g = *GImGui;
+    ImGuiWindowFlags flags = window->Flags;
+    window->ViewportAllowPlatformMonitorExtend = -1;
+
+    // Restore main viewport if multi-viewport is not supported by the backend
+    ImGuiViewportP* main_viewport = (ImGuiViewportP*)(void*)GetMainViewport();
+    if (!(g.ConfigFlagsCurrFrame & ImGuiConfigFlags_ViewportsEnable))
+    {
+        SetWindowViewport(window, main_viewport);
+        return;
+    }
+    window->ViewportOwned = false;
+
+    // Appearing popups reset their viewport so they can inherit again
+    if ((flags & (ImGuiWindowFlags_Popup | ImGuiWindowFlags_Tooltip)) && window->Appearing)
+    {
+        window->Viewport = NULL;
+        window->ViewportId = 0;
+    }
+
+    if ((g.NextWindowData.HasFlags & ImGuiNextWindowDataFlags_HasViewport) == 0)
+    {
+        // By default inherit from parent window
+        if (window->Viewport == NULL && window->ParentWindow && (!window->ParentWindow->IsFallbackWindow || window->ParentWindow->WasActive))
+            window->Viewport = window->ParentWindow->Viewport;
+
+        // Attempt to restore saved viewport id (= window that hasn't been activated yet), try to restore the viewport based on saved 'window->ViewportPos' restored from .ini file
+        if (window->Viewport == NULL && window->ViewportId != 0)
+        {
+            window->Viewport = (ImGuiViewportP*)FindViewportByID(window->ViewportId);
+            if (window->Viewport == NULL && window->ViewportPos.x != FLT_MAX && window->ViewportPos.y != FLT_MAX)
+                window->Viewport = AddUpdateViewport(window, window->ID, window->ViewportPos, window->Size, ImGuiViewportFlags_None);
+        }
+    }
+
+    bool lock_viewport = false;
+    if (g.NextWindowData.HasFlags & ImGuiNextWindowDataFlags_HasViewport)
+    {
+        // Code explicitly request a viewport
+        window->Viewport = (ImGuiViewportP*)FindViewportByID(g.NextWindowData.ViewportId);
+        window->ViewportId = g.NextWindowData.ViewportId; // Store ID even if Viewport isn't resolved yet.
+        if (window->Viewport && (window->Flags & ImGuiWindowFlags_DockNodeHost) != 0 && window->Viewport->Window != NULL)
+        {
+            window->Viewport->Window = window;
+            window->Viewport->ID = window->ViewportId = window->ID; // Overwrite ID (always owned by node)
+        }
+        lock_viewport = true;
+    }
+    else if ((flags & ImGuiWindowFlags_ChildWindow) || (flags & ImGuiWindowFlags_ChildMenu))
+    {
+        // Always inherit viewport from parent window
+        if (window->DockNode && window->DockNode->HostWindow)
+            IM_ASSERT(window->DockNode->HostWindow->Viewport == window->ParentWindow->Viewport);
+        window->Viewport = window->ParentWindow->Viewport;
+    }
+    else if (window->DockNode && window->DockNode->HostWindow)
+    {
+        // This covers the "always inherit viewport from parent window" case for when a window reattach to a node that was just created mid-frame
+        window->Viewport = window->DockNode->HostWindow->Viewport;
+    }
+    else if (flags & ImGuiWindowFlags_Tooltip)
+    {
+        window->Viewport = g.MouseViewport;
+    }
+    else if (GetWindowAlwaysWantOwnViewport(window))
+    {
+        window->Viewport = AddUpdateViewport(window, window->ID, window->Pos, window->Size, ImGuiViewportFlags_None);
+    }
+    else if (g.MovingWindow && g.MovingWindow->RootWindowDockTree == window && IsMousePosValid())
+    {
+        if (window->Viewport != NULL && window->Viewport->Window == window)
+            window->Viewport = AddUpdateViewport(window, window->ID, window->Pos, window->Size, ImGuiViewportFlags_None);
+    }
+    else
+    {
+        // Merge into host viewport?
+        // We cannot test window->ViewportOwned as it set lower in the function.
+        // Testing (g.ActiveId == 0 || g.ActiveIdAllowOverlap) to avoid merging during a short-term widget interaction. Main intent was to avoid during resize (see #4212)
+        bool try_to_merge_into_host_viewport = (window->Viewport && window == window->Viewport->Window && (g.ActiveId == 0 || g.ActiveIdAllowOverlap));
+        if (try_to_merge_into_host_viewport)
+            UpdateTryMergeWindowIntoHostViewports(window);
+    }
+
+    // Fallback: merge in default viewport if z-order matches, otherwise create a new viewport
+    if (window->Viewport == NULL)
+        if (!UpdateTryMergeWindowIntoHostViewport(window, main_viewport))
+            window->Viewport = AddUpdateViewport(window, window->ID, window->Pos, window->Size, ImGuiViewportFlags_None);
+
+    // Mark window as allowed to protrude outside of its viewport and into the current monitor
+    if (!lock_viewport)
+    {
+        if (flags & (ImGuiWindowFlags_Tooltip | ImGuiWindowFlags_Popup))
+        {
+            // We need to take account of the possibility that mouse may become invalid.
+            // Popups/Tooltip always set ViewportAllowPlatformMonitorExtend so GetWindowAllowedExtentRect() will return full monitor bounds.
+            ImVec2 mouse_ref = (flags & ImGuiWindowFlags_Tooltip) ? g.IO.MousePos : g.BeginPopupStack.back().OpenMousePos;
+            bool use_mouse_ref = (!g.NavCursorVisible || !g.NavHighlightItemUnderNav || !g.NavWindow);
+            bool mouse_valid = IsMousePosValid(&mouse_ref);
+            if ((window->Appearing || (flags & (ImGuiWindowFlags_Tooltip | ImGuiWindowFlags_ChildMenu))) && (!use_mouse_ref || mouse_valid))
+                window->ViewportAllowPlatformMonitorExtend = FindPlatformMonitorForPos((use_mouse_ref && mouse_valid) ? mouse_ref : NavCalcPreferredRefPos(window->Flags));
+            else
+                window->ViewportAllowPlatformMonitorExtend = window->Viewport->PlatformMonitor;
+        }
+        else if (window->Viewport && window != window->Viewport->Window && window->Viewport->Window && !(flags & ImGuiWindowFlags_ChildWindow) && window->DockNode == NULL)
+        {
+            // When called from Begin() we don't have access to a proper version of the Hidden flag yet, so we replicate this code.
+            const bool will_be_visible = (window->DockIsActive && !window->DockTabIsVisible) ? false : true;
+            if ((window->Flags & ImGuiWindowFlags_DockNodeHost) && window->Viewport->LastFrameActive < g.FrameCount && will_be_visible)
+            {
+                // Steal/transfer ownership
+                IMGUI_DEBUG_LOG_VIEWPORT("[viewport] Window '%s' steal Viewport %08X from Window '%s'\n", window->Name, window->Viewport->ID, window->Viewport->Window->Name);
+                window->Viewport->Window = window;
+                window->Viewport->ID = window->ID;
+                window->Viewport->LastNameHash = 0;
+            }
+            else if (!UpdateTryMergeWindowIntoHostViewports(window)) // Merge?
+            {
+                // New viewport
+                window->Viewport = AddUpdateViewport(window, window->ID, window->Pos, window->Size, ImGuiViewportFlags_NoFocusOnAppearing);
+            }
+        }
+        else if (window->ViewportAllowPlatformMonitorExtend < 0 && (flags & ImGuiWindowFlags_ChildWindow) == 0)
+        {
+            // Regular (non-child, non-popup) windows by default are also allowed to protrude
+            // Child windows are kept contained within their parent.
+            window->ViewportAllowPlatformMonitorExtend = window->Viewport->PlatformMonitor;
+        }
+    }
+
+    // Update flags
+    window->ViewportOwned = (window == window->Viewport->Window);
+    window->ViewportId = window->Viewport->ID;
+
+    // If the OS window has a title bar, hide our imgui title bar
+    //if (window->ViewportOwned && !(window->Viewport->Flags & ImGuiViewportFlags_NoDecoration))
+    //    window->Flags |= ImGuiWindowFlags_NoTitleBar;
+}
+
+void ImGui::WindowSyncOwnedViewport(ImGuiWindow* window, ImGuiWindow* parent_window_in_stack)
+{
+    ImGuiContext& g = *GImGui;
+
+    bool viewport_rect_changed = false;
+
+    // Synchronize window --> viewport in most situations
+    // Synchronize viewport -> window in case the platform window has been moved or resized from the OS/WM
+    if (window->Viewport->PlatformRequestMove)
+    {
+        window->Pos = window->Viewport->Pos;
+        MarkIniSettingsDirty(window);
+    }
+    else if (memcmp(&window->Viewport->Pos, &window->Pos, sizeof(window->Pos)) != 0)
+    {
+        viewport_rect_changed = true;
+        window->Viewport->Pos = window->Pos;
+    }
+
+    if (window->Viewport->PlatformRequestResize)
+    {
+        window->Size = window->SizeFull = window->Viewport->Size;
+        MarkIniSettingsDirty(window);
+    }
+    else if (memcmp(&window->Viewport->Size, &window->Size, sizeof(window->Size)) != 0)
+    {
+        viewport_rect_changed = true;
+        window->Viewport->Size = window->Size;
+    }
+    window->Viewport->UpdateWorkRect();
+
+    // The viewport may have changed monitor since the global update in UpdateViewportsNewFrame()
+    // Either a SetNextWindowPos() call in the current frame or a SetWindowPos() call in the previous frame may have this effect.
+    if (viewport_rect_changed)
+        UpdateViewportPlatformMonitor(window->Viewport);
+
+    // Update common viewport flags
+    const ImGuiViewportFlags viewport_flags_to_clear = ImGuiViewportFlags_TopMost | ImGuiViewportFlags_NoTaskBarIcon | ImGuiViewportFlags_NoDecoration | ImGuiViewportFlags_NoRendererClear;
+    ImGuiViewportFlags viewport_flags = window->Viewport->Flags & ~viewport_flags_to_clear;
+    ImGuiWindowFlags window_flags = window->Flags;
+    const bool is_modal = (window_flags & ImGuiWindowFlags_Modal) != 0;
+    const bool is_short_lived_floating_window = (window_flags & (ImGuiWindowFlags_ChildMenu | ImGuiWindowFlags_Tooltip | ImGuiWindowFlags_Popup)) != 0;
+    if (window_flags & ImGuiWindowFlags_Tooltip)
+        viewport_flags |= ImGuiViewportFlags_TopMost;
+    if ((g.IO.ConfigViewportsNoTaskBarIcon || is_short_lived_floating_window) && !is_modal)
+        viewport_flags |= ImGuiViewportFlags_NoTaskBarIcon;
+    if (g.IO.ConfigViewportsNoDecoration || is_short_lived_floating_window)
+        viewport_flags |= ImGuiViewportFlags_NoDecoration;
+
+    // Not correct to set modal as topmost because:
+    // - Because other popups can be stacked above a modal (e.g. combo box in a modal)
+    // - ImGuiViewportFlags_TopMost is currently handled different in backends: in Win32 it is "appear top most" whereas in GLFW and SDL it is "stay topmost"
+    //if (flags & ImGuiWindowFlags_Modal)
+    //    viewport_flags |= ImGuiViewportFlags_TopMost;
+
+    // For popups and menus that may be protruding out of their parent viewport, we enable _NoFocusOnClick so that clicking on them
+    // won't steal the OS focus away from their parent window (which may be reflected in OS the title bar decoration).
+    // Setting _NoFocusOnClick would technically prevent us from bringing back to front in case they are being covered by an OS window from a different app,
+    // but it shouldn't be much of a problem considering those are already popups that are closed when clicking elsewhere.
+    if (is_short_lived_floating_window && !is_modal)
+        viewport_flags |= ImGuiViewportFlags_NoFocusOnAppearing | ImGuiViewportFlags_NoFocusOnClick;
+
+    // We can overwrite viewport flags using ImGuiWindowClass (advanced users)
+    if (window->WindowClass.ViewportFlagsOverrideSet)
+        viewport_flags |= window->WindowClass.ViewportFlagsOverrideSet;
+    if (window->WindowClass.ViewportFlagsOverrideClear)
+        viewport_flags &= ~window->WindowClass.ViewportFlagsOverrideClear;
+
+    // We can also tell the backend that clearing the platform window won't be necessary,
+    // as our window background is filling the viewport and we have disabled BgAlpha.
+    // FIXME: Work on support for per-viewport transparency (#2766)
+    if (!(window_flags & ImGuiWindowFlags_NoBackground))
+        viewport_flags |= ImGuiViewportFlags_NoRendererClear;
+
+    window->Viewport->Flags = viewport_flags;
+
+    // Update parent viewport ID
+    // (the !IsFallbackWindow test mimic the one done in WindowSelectViewport())
+    if (window->WindowClass.ParentViewportId != (ImGuiID)-1)
+    {
+        ImGuiID old_parent_viewport_id = window->Viewport->ParentViewportId;
+        window->Viewport->ParentViewportId = window->WindowClass.ParentViewportId;
+        if (window->Viewport->ParentViewportId != old_parent_viewport_id)
+            window->Viewport->ParentViewport = FindViewportByID(window->Viewport->ParentViewportId);
+    }
+    else if ((window_flags & (ImGuiWindowFlags_Popup | ImGuiWindowFlags_Tooltip)) && parent_window_in_stack && (!parent_window_in_stack->IsFallbackWindow || parent_window_in_stack->WasActive))
+    {
+        window->Viewport->ParentViewport = parent_window_in_stack->Viewport;
+        window->Viewport->ParentViewportId = parent_window_in_stack->Viewport->ID;
+    }
+    else
+    {
+        window->Viewport->ParentViewport = g.IO.ConfigViewportsNoDefaultParent ? NULL : GetMainViewport();
+        window->Viewport->ParentViewportId = g.IO.ConfigViewportsNoDefaultParent ? 0 : IMGUI_VIEWPORT_DEFAULT_ID;
     }
 }
 
+// Called by user at the end of the main loop, after EndFrame()
+// This will handle the creation/update of all OS windows via function defined in the ImGuiPlatformIO api.
+void ImGui::UpdatePlatformWindows()
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(g.FrameCountEnded == g.FrameCount && "Forgot to call Render() or EndFrame() before UpdatePlatformWindows()?");
+    IM_ASSERT(g.FrameCountPlatformEnded < g.FrameCount);
+    g.FrameCountPlatformEnded = g.FrameCount;
+    if (!(g.ConfigFlagsCurrFrame & ImGuiConfigFlags_ViewportsEnable))
+        return;
+
+    // Create/resize/destroy platform windows to match each active viewport.
+    // Skip the main viewport (index 0), which is always fully handled by the application!
+    for (int i = 1; i < g.Viewports.Size; i++)
+    {
+        ImGuiViewportP* viewport = g.Viewports[i];
+
+        // Destroy platform window if the viewport hasn't been submitted or if it is hosting a hidden window
+        // (the implicit/fallback Debug##Default window will be registering its viewport then be disabled, causing a dummy DestroyPlatformWindow to be made each frame)
+        bool destroy_platform_window = false;
+        destroy_platform_window |= (viewport->LastFrameActive < g.FrameCount - 1);
+        destroy_platform_window |= (viewport->Window && !IsWindowActiveAndVisible(viewport->Window));
+        if (destroy_platform_window)
+        {
+            DestroyPlatformWindow(viewport);
+            continue;
+        }
+
+        // New windows that appears directly in a new viewport won't always have a size on their first frame
+        if (viewport->LastFrameActive < g.FrameCount || viewport->Size.x <= 0 || viewport->Size.y <= 0)
+            continue;
+
+        // Create window
+        const bool is_new_platform_window = (viewport->PlatformWindowCreated == false);
+        if (is_new_platform_window)
+        {
+            IMGUI_DEBUG_LOG_VIEWPORT("[viewport] Create Platform Window %08X '%s'\n", viewport->ID, viewport->Window ? viewport->Window->Name : "n/a");
+            g.PlatformIO.Platform_CreateWindow(viewport);
+            if (g.PlatformIO.Renderer_CreateWindow != NULL)
+                g.PlatformIO.Renderer_CreateWindow(viewport);
+            g.PlatformWindowsCreatedCount++;
+            viewport->LastNameHash = 0;
+            viewport->LastPlatformPos = viewport->LastPlatformSize = ImVec2(FLT_MAX, FLT_MAX); // By clearing those we'll enforce a call to Platform_SetWindowPos/Size below, before Platform_ShowWindow (FIXME: Is that necessary?)
+            viewport->LastRendererSize = viewport->Size;                                       // We don't need to call Renderer_SetWindowSize() as it is expected Renderer_CreateWindow() already did it.
+            viewport->PlatformWindowCreated = true;
+        }
+
+        // Apply Position and Size (from ImGui to Platform/Renderer backends)
+        if ((viewport->LastPlatformPos.x != viewport->Pos.x || viewport->LastPlatformPos.y != viewport->Pos.y) && !viewport->PlatformRequestMove)
+            g.PlatformIO.Platform_SetWindowPos(viewport, viewport->Pos);
+        if ((viewport->LastPlatformSize.x != viewport->Size.x || viewport->LastPlatformSize.y != viewport->Size.y) && !viewport->PlatformRequestResize)
+            g.PlatformIO.Platform_SetWindowSize(viewport, viewport->Size);
+        if ((viewport->LastRendererSize.x != viewport->Size.x || viewport->LastRendererSize.y != viewport->Size.y) && g.PlatformIO.Renderer_SetWindowSize)
+            g.PlatformIO.Renderer_SetWindowSize(viewport, viewport->Size);
+        viewport->LastPlatformPos = viewport->Pos;
+        viewport->LastPlatformSize = viewport->LastRendererSize = viewport->Size;
+
+        // Update title bar (if it changed)
+        if (ImGuiWindow* window_for_title = GetWindowForTitleDisplay(viewport->Window))
+        {
+            const char* title_begin = window_for_title->Name;
+            char* title_end = (char*)(intptr_t)FindRenderedTextEnd(title_begin);
+            const ImGuiID title_hash = ImHashStr(title_begin, title_end - title_begin);
+            if (viewport->LastNameHash != title_hash)
+            {
+                char title_end_backup_c = *title_end;
+                *title_end = 0; // Cut existing buffer short instead of doing an alloc/free, no small gain.
+                g.PlatformIO.Platform_SetWindowTitle(viewport, title_begin);
+                *title_end = title_end_backup_c;
+                viewport->LastNameHash = title_hash;
+            }
+        }
+
+        // Update alpha (if it changed)
+        if (viewport->LastAlpha != viewport->Alpha && g.PlatformIO.Platform_SetWindowAlpha)
+            g.PlatformIO.Platform_SetWindowAlpha(viewport, viewport->Alpha);
+        viewport->LastAlpha = viewport->Alpha;
+
+        // Optional, general purpose call to allow the backend to perform general book-keeping even if things haven't changed.
+        if (g.PlatformIO.Platform_UpdateWindow)
+            g.PlatformIO.Platform_UpdateWindow(viewport);
+
+        if (is_new_platform_window)
+        {
+            // On startup ensure new platform window don't steal focus (give it a few frames, as nested contents may lead to viewport being created a few frames late)
+            if (g.FrameCount < 3)
+                viewport->Flags |= ImGuiViewportFlags_NoFocusOnAppearing;
+
+            // Show window
+            g.PlatformIO.Platform_ShowWindow(viewport);
+        }
+
+        // Clear request flags
+        viewport->ClearRequestFlags();
+    }
+}
+
+// This is a default/basic function for performing the rendering/swap of multiple Platform Windows.
+// Custom renderers may prefer to not call this function at all, and instead iterate the publicly exposed platform data and handle rendering/sync themselves.
+// The Render/Swap functions stored in ImGuiPlatformIO are merely here to allow for this helper to exist, but you can do it yourself:
+//
+//    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+//    for (int i = 1; i < platform_io.Viewports.Size; i++)
+//        if ((platform_io.Viewports[i]->Flags & ImGuiViewportFlags_Minimized) == 0)
+//            MyRenderFunction(platform_io.Viewports[i], my_args);
+//    for (int i = 1; i < platform_io.Viewports.Size; i++)
+//        if ((platform_io.Viewports[i]->Flags & ImGuiViewportFlags_Minimized) == 0)
+//            MySwapBufferFunction(platform_io.Viewports[i], my_args);
+//
+void ImGui::RenderPlatformWindowsDefault(void* platform_render_arg, void* renderer_render_arg)
+{
+    // Skip the main viewport (index 0), which is always fully handled by the application!
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+    for (int i = 1; i < platform_io.Viewports.Size; i++)
+    {
+        ImGuiViewport* viewport = platform_io.Viewports[i];
+        if (viewport->Flags & ImGuiViewportFlags_IsMinimized)
+            continue;
+        if (platform_io.Platform_RenderWindow) platform_io.Platform_RenderWindow(viewport, platform_render_arg);
+        if (platform_io.Renderer_RenderWindow) platform_io.Renderer_RenderWindow(viewport, renderer_render_arg);
+    }
+    for (int i = 1; i < platform_io.Viewports.Size; i++)
+    {
+        ImGuiViewport* viewport = platform_io.Viewports[i];
+        if (viewport->Flags & ImGuiViewportFlags_IsMinimized)
+            continue;
+        if (platform_io.Platform_SwapBuffers) platform_io.Platform_SwapBuffers(viewport, platform_render_arg);
+        if (platform_io.Renderer_SwapBuffers) platform_io.Renderer_SwapBuffers(viewport, renderer_render_arg);
+    }
+}
+
+static int ImGui::FindPlatformMonitorForPos(const ImVec2& pos)
+{
+    ImGuiContext& g = *GImGui;
+    for (int monitor_n = 0; monitor_n < g.PlatformIO.Monitors.Size; monitor_n++)
+    {
+        const ImGuiPlatformMonitor& monitor = g.PlatformIO.Monitors[monitor_n];
+        if (ImRect(monitor.MainPos, monitor.MainPos + monitor.MainSize).Contains(pos))
+            return monitor_n;
+    }
+    return -1;
+}
+
+// Search for the monitor with the largest intersection area with the given rectangle
+// We generally try to avoid searching loops but the monitor count should be very small here
+// FIXME-OPT: We could test the last monitor used for that viewport first, and early
+static int ImGui::FindPlatformMonitorForRect(const ImRect& rect)
+{
+    ImGuiContext& g = *GImGui;
+
+    const int monitor_count = g.PlatformIO.Monitors.Size;
+    if (monitor_count <= 1)
+        return monitor_count - 1;
+
+    // Use a minimum threshold of 1.0f so a zero-sized rect won't false positive, and will still find the correct monitor given its position.
+    // This is necessary for tooltips which always resize down to zero at first.
+    const float surface_threshold = ImMax(rect.GetWidth() * rect.GetHeight() * 0.5f, 1.0f);
+    int best_monitor_n = 0; // Default to the first monitor as fallback
+    float best_monitor_surface = 0.001f;
+
+    for (int monitor_n = 0; monitor_n < g.PlatformIO.Monitors.Size && best_monitor_surface < surface_threshold; monitor_n++)
+    {
+        const ImGuiPlatformMonitor& monitor = g.PlatformIO.Monitors[monitor_n];
+        const ImRect monitor_rect = ImRect(monitor.MainPos, monitor.MainPos + monitor.MainSize);
+        if (monitor_rect.Contains(rect))
+            return monitor_n;
+        ImRect overlapping_rect = rect;
+        overlapping_rect.ClipWithFull(monitor_rect);
+        float overlapping_surface = overlapping_rect.GetWidth() * overlapping_rect.GetHeight();
+        if (overlapping_surface < best_monitor_surface)
+            continue;
+        best_monitor_surface = overlapping_surface;
+        best_monitor_n = monitor_n;
+    }
+    return best_monitor_n;
+}
+
+// Update monitor from viewport rectangle (we'll use this info to clamp windows and save windows lost in a removed monitor)
+static void ImGui::UpdateViewportPlatformMonitor(ImGuiViewportP* viewport)
+{
+    viewport->PlatformMonitor = (short)FindPlatformMonitorForRect(viewport->GetMainRect());
+}
+
+// Return value is always != NULL, but don't hold on it across frames.
+const ImGuiPlatformMonitor* ImGui::GetViewportPlatformMonitor(ImGuiViewport* viewport_p)
+{
+    ImGuiContext& g = *GImGui;
+    ImGuiViewportP* viewport = (ImGuiViewportP*)(void*)viewport_p;
+    int monitor_idx = viewport->PlatformMonitor;
+    if (monitor_idx >= 0 && monitor_idx < g.PlatformIO.Monitors.Size)
+        return &g.PlatformIO.Monitors[monitor_idx];
+    return &g.FallbackMonitor;
+}
+
+void ImGui::DestroyPlatformWindow(ImGuiViewportP* viewport)
+{
+    ImGuiContext& g = *GImGui;
+    if (viewport->PlatformWindowCreated)
+    {
+        IMGUI_DEBUG_LOG_VIEWPORT("[viewport] Destroy Platform Window %08X '%s'\n", viewport->ID, viewport->Window ? viewport->Window->Name : "n/a");
+        if (g.PlatformIO.Renderer_DestroyWindow)
+            g.PlatformIO.Renderer_DestroyWindow(viewport);
+        if (g.PlatformIO.Platform_DestroyWindow)
+            g.PlatformIO.Platform_DestroyWindow(viewport);
+        IM_ASSERT(viewport->RendererUserData == NULL && viewport->PlatformUserData == NULL);
+
+        // Don't clear PlatformWindowCreated for the main viewport, as we initially set that up to true in Initialize()
+        // The righter way may be to leave it to the backend to set this flag all-together, and made the flag public.
+        if (viewport->ID != IMGUI_VIEWPORT_DEFAULT_ID)
+            viewport->PlatformWindowCreated = false;
+    }
+    else
+    {
+        IM_ASSERT(viewport->RendererUserData == NULL && viewport->PlatformUserData == NULL && viewport->PlatformHandle == NULL);
+    }
+    viewport->RendererUserData = viewport->PlatformUserData = viewport->PlatformHandle = NULL;
+    viewport->ClearRequestFlags();
+}
+
+void ImGui::DestroyPlatformWindows()
+{
+    // We call the destroy window on every viewport (including the main viewport, index 0) to give a chance to the backend
+    // to clear any data they may have stored in e.g. PlatformUserData, RendererUserData.
+    // It is convenient for the platform backend code to store something in the main viewport, in order for e.g. the mouse handling
+    // code to operator a consistent manner.
+    // It is expected that the backend can handle calls to Renderer_DestroyWindow/Platform_DestroyWindow without
+    // crashing if it doesn't have data stored.
+    ImGuiContext& g = *GImGui;
+    for (ImGuiViewportP* viewport : g.Viewports)
+        DestroyPlatformWindow(viewport);
+}
+
+
 //-----------------------------------------------------------------------------
 // [SECTION] DOCKING
 //-----------------------------------------------------------------------------
+// Docking: Internal Types
+// Docking: Forward Declarations
+// Docking: ImGuiDockContext
+// Docking: ImGuiDockContext Docking/Undocking functions
+// Docking: ImGuiDockNode
+// Docking: ImGuiDockNode Tree manipulation functions
+// Docking: Public Functions (SetWindowDock, DockSpace, DockSpaceOverViewport)
+// Docking: Builder Functions
+// Docking: Begin/End Support Functions (called from Begin/End)
+// Docking: Settings
+//-----------------------------------------------------------------------------
 
-// (this section is filled in the 'docking' branch)
+//-----------------------------------------------------------------------------
+// Typical Docking call flow: (root level is generally public API):
+//-----------------------------------------------------------------------------
+// - NewFrame()                               new dear imgui frame
+//    | DockContextNewFrameUpdateUndocking()  - process queued undocking requests
+//    | - DockContextProcessUndockWindow()    - process one window undocking request
+//    | - DockContextProcessUndockNode()      - process one whole node undocking request
+//    | DockContextNewFrameUpdateUndocking()  - process queue docking requests, create floating dock nodes
+//    | - update g.HoveredDockNode            - [debug] update node hovered by mouse
+//    | - DockContextProcessDock()            - process one docking request
+//    | - DockNodeUpdate()
+//    |   - DockNodeUpdateForRootNode()
+//    |     - DockNodeUpdateFlagsAndCollapse()
+//    |     - DockNodeFindInfo()
+//    |   - destroy unused node or tab bar
+//    |   - create dock node host window
+//    |      - Begin() etc.
+//    |   - DockNodeStartMouseMovingWindow()
+//    |   - DockNodeTreeUpdatePosSize()
+//    |   - DockNodeTreeUpdateSplitter()
+//    |   - draw node background
+//    |   - DockNodeUpdateTabBar()            - create/update tab bar for a docking node
+//    |     - DockNodeAddTabBar()
+//    |     - DockNodeWindowMenuUpdate()
+//    |     - DockNodeCalcTabBarLayout()
+//    |     - BeginTabBarEx()
+//    |     - TabItemEx() calls
+//    |     - EndTabBar()
+//    |   - BeginDockableDragDropTarget()
+//    |      - DockNodeUpdate()               - recurse into child nodes...
+//-----------------------------------------------------------------------------
+// - DockSpace()                              user submit a dockspace into a window
+//    | Begin(Child)                          - create a child window
+//    | DockNodeUpdate()                      - call main dock node update function
+//    | End(Child)
+//    | ItemSize()
+//-----------------------------------------------------------------------------
+// - Begin()
+//    | BeginDocked()
+//    | BeginDockableDragDropSource()
+//    | BeginDockableDragDropTarget()
+//    | - DockNodePreviewDockRender()
+//-----------------------------------------------------------------------------
+// - EndFrame()
+//    | DockContextEndFrame()
+//-----------------------------------------------------------------------------
+
+//-----------------------------------------------------------------------------
+// Docking: Internal Types
+//-----------------------------------------------------------------------------
+// - ImGuiDockRequestType
+// - ImGuiDockRequest
+// - ImGuiDockPreviewData
+// - ImGuiDockNodeSettings
+// - ImGuiDockContext
+//-----------------------------------------------------------------------------
+
+enum ImGuiDockRequestType
+{
+    ImGuiDockRequestType_None = 0,
+    ImGuiDockRequestType_Dock,
+    ImGuiDockRequestType_Undock,
+    ImGuiDockRequestType_Split                  // Split is the same as Dock but without a DockPayload
+};
+
+struct ImGuiDockRequest
+{
+    ImGuiDockRequestType    Type;
+    ImGuiWindow*            DockTargetWindow;   // Destination/Target Window to dock into (may be a loose window or a DockNode, might be NULL in which case DockTargetNode cannot be NULL)
+    ImGuiDockNode*          DockTargetNode;     // Destination/Target Node to dock into
+    ImGuiWindow*            DockPayload;        // Source/Payload window to dock (may be a loose window or a DockNode), [Optional]
+    ImGuiDir                DockSplitDir;
+    float                   DockSplitRatio;
+    bool                    DockSplitOuter;
+    ImGuiWindow*            UndockTargetWindow;
+    ImGuiDockNode*          UndockTargetNode;
+
+    ImGuiDockRequest()
+    {
+        Type = ImGuiDockRequestType_None;
+        DockTargetWindow = DockPayload = UndockTargetWindow = NULL;
+        DockTargetNode = UndockTargetNode = NULL;
+        DockSplitDir = ImGuiDir_None;
+        DockSplitRatio = 0.5f;
+        DockSplitOuter = false;
+    }
+};
+
+struct ImGuiDockPreviewData
+{
+    ImGuiDockNode   FutureNode;
+    bool            IsDropAllowed;
+    bool            IsCenterAvailable;
+    bool            IsSidesAvailable;           // Hold your breath, grammar freaks..
+    bool            IsSplitDirExplicit;         // Set when hovered the drop rect (vs. implicit SplitDir==None when hovered the window)
+    ImGuiDockNode*  SplitNode;
+    ImGuiDir        SplitDir;
+    float           SplitRatio;
+    ImRect          DropRectsDraw[ImGuiDir_COUNT + 1];  // May be slightly different from hit-testing drop rects used in DockNodeCalcDropRects()
+
+    ImGuiDockPreviewData() : FutureNode(0) { IsDropAllowed = IsCenterAvailable = IsSidesAvailable = IsSplitDirExplicit = false; SplitNode = NULL; SplitDir = ImGuiDir_None; SplitRatio = 0.f; for (int n = 0; n < IM_COUNTOF(DropRectsDraw); n++) DropRectsDraw[n] = ImRect(+FLT_MAX, +FLT_MAX, -FLT_MAX, -FLT_MAX); }
+};
+
+// Persistent Settings data, stored contiguously in SettingsNodes (sizeof() ~32 bytes)
+struct ImGuiDockNodeSettings
+{
+    ImGuiID             ID;
+    ImGuiID             ParentNodeId;
+    ImGuiID             ParentWindowId;
+    ImGuiID             SelectedTabId;
+    signed char         SplitAxis;
+    char                Depth;
+    ImGuiDockNodeFlags  Flags;                  // NB: We save individual flags one by one in ascii format (ImGuiDockNodeFlags_SavedFlagsMask_)
+    ImVec2ih            Pos;
+    ImVec2ih            Size;
+    ImVec2ih            SizeRef;
+    ImGuiDockNodeSettings() { memset((void*)this, 0, sizeof(*this)); SplitAxis = ImGuiAxis_None; }
+};
+
+//-----------------------------------------------------------------------------
+// Docking: Forward Declarations
+//-----------------------------------------------------------------------------
+
+namespace ImGui
+{
+    // ImGuiDockContext
+    static ImGuiDockNode*   DockContextAddNode(ImGuiContext* ctx, ImGuiID id);
+    static void             DockContextRemoveNode(ImGuiContext* ctx, ImGuiDockNode* node, bool merge_sibling_into_parent_node);
+    static void             DockContextDeleteNode(ImGuiContext* ctx, ImGuiDockNode* node);
+    static void             DockContextQueueNotifyRemovedNode(ImGuiContext* ctx, ImGuiDockNode* node);
+    static void             DockContextProcessDock(ImGuiContext* ctx, ImGuiDockRequest* req);
+    static void             DockContextPruneUnusedSettingsNodes(ImGuiContext* ctx);
+    static ImGuiDockNode*   DockContextBindNodeToWindow(ImGuiContext* ctx, ImGuiWindow* window);
+    static void             DockContextBuildNodesFromSettings(ImGuiContext* ctx, ImGuiDockNodeSettings* node_settings_array, int node_settings_count);
+    static void             DockContextBuildAddWindowsToNodes(ImGuiContext* ctx, ImGuiID root_id);                            // Use root_id==0 to add all
+
+    // ImGuiDockNode
+    static void             DockNodeAddWindow(ImGuiDockNode* node, ImGuiWindow* window, bool add_to_tab_bar);
+    static void             DockNodeMoveWindows(ImGuiDockNode* dst_node, ImGuiDockNode* src_node);
+    static void             DockNodeMoveChildNodes(ImGuiDockNode* dst_node, ImGuiDockNode* src_node);
+    static ImGuiWindow*     DockNodeFindWindowByID(ImGuiDockNode* node, ImGuiID id);
+    static void             DockNodeApplyPosSizeToWindows(ImGuiDockNode* node);
+    static void             DockNodeRemoveWindow(ImGuiDockNode* node, ImGuiWindow* window, ImGuiID save_dock_id);
+    static void             DockNodeHideHostWindow(ImGuiDockNode* node);
+    static void             DockNodeUpdate(ImGuiDockNode* node);
+    static void             DockNodeUpdateForRootNode(ImGuiDockNode* node);
+    static void             DockNodeUpdateFlagsAndCollapse(ImGuiDockNode* node);
+    static void             DockNodeUpdateHasCentralNodeChild(ImGuiDockNode* node);
+    static void             DockNodeUpdateTabBar(ImGuiDockNode* node, ImGuiWindow* host_window);
+    static void             DockNodeAddTabBar(ImGuiDockNode* node);
+    static void             DockNodeRemoveTabBar(ImGuiDockNode* node);
+    static void             DockNodeWindowMenuUpdate(ImGuiDockNode* node, ImGuiTabBar* tab_bar);
+    static void             DockNodeUpdateVisibleFlag(ImGuiDockNode* node);
+    static void             DockNodeStartMouseMovingWindow(ImGuiDockNode* node, ImGuiWindow* window);
+    static bool             DockNodeIsDropAllowed(ImGuiWindow* host_window, ImGuiWindow* payload_window);
+    static void             DockNodePreviewDockSetup(ImGuiWindow* host_window, ImGuiDockNode* host_node, ImGuiWindow* payload_window, ImGuiDockNode* payload_node, ImGuiDockPreviewData* preview_data, bool is_explicit_target, bool is_outer_docking);
+    static void             DockNodePreviewDockRender(ImGuiWindow* host_window, ImGuiDockNode* host_node, ImGuiWindow* payload_window, const ImGuiDockPreviewData* preview_data);
+    static void             DockNodeCalcTabBarLayout(const ImGuiDockNode* node, ImRect* out_title_rect, ImRect* out_tab_bar_rect, ImVec2* out_window_menu_button_pos, ImVec2* out_close_button_pos);
+    static void             DockNodeCalcSplitRects(ImVec2& pos_old, ImVec2& size_old, ImVec2& pos_new, ImVec2& size_new, ImGuiDir dir, ImVec2 size_new_desired);
+    static bool             DockNodeCalcDropRectsAndTestMousePos(const ImRect& parent, ImGuiDir dir, ImRect& out_draw, bool outer_docking, ImVec2* test_mouse_pos);
+    static const char*      DockNodeGetHostWindowTitle(ImGuiDockNode* node, char* buf, int buf_size) { ImFormatString(buf, buf_size, "##DockNode_%02X", node->ID); return buf; }
+    static int              DockNodeGetTabOrder(ImGuiWindow* window);
+
+    // ImGuiDockNode tree manipulations
+    static void             DockNodeTreeSplit(ImGuiContext* ctx, ImGuiDockNode* parent_node, ImGuiAxis split_axis, int split_first_child, float split_ratio, ImGuiDockNode* new_node);
+    static void             DockNodeTreeMerge(ImGuiContext* ctx, ImGuiDockNode* parent_node, ImGuiDockNode* merge_lead_child);
+    static void             DockNodeTreeUpdatePosSize(ImGuiDockNode* node, ImVec2 pos, ImVec2 size, ImGuiDockNode* only_write_to_single_node = NULL);
+    static void             DockNodeTreeUpdateSplitter(ImGuiDockNode* node);
+    static ImGuiDockNode*   DockNodeTreeFindVisibleNodeByPos(ImGuiDockNode* node, ImVec2 pos);
+    static ImGuiDockNode*   DockNodeTreeFindFallbackLeafNode(ImGuiDockNode* node);
+
+    // Settings
+    static void             DockSettingsRenameNodeReferences(ImGuiID old_node_id, ImGuiID new_node_id);
+    static void             DockSettingsRemoveNodeReferences(ImGuiID* node_ids, int node_ids_count);
+    static ImGuiDockNodeSettings*   DockSettingsFindNodeSettings(ImGuiContext* ctx, ImGuiID node_id);
+    static void             DockSettingsHandler_ClearAll(ImGuiContext*, ImGuiSettingsHandler*);
+    static void             DockSettingsHandler_ApplyAll(ImGuiContext*, ImGuiSettingsHandler*);
+    static void*            DockSettingsHandler_ReadOpen(ImGuiContext*, ImGuiSettingsHandler*, const char* name);
+    static void             DockSettingsHandler_ReadLine(ImGuiContext*, ImGuiSettingsHandler*, void* entry, const char* line);
+    static void             DockSettingsHandler_WriteAll(ImGuiContext* imgui_ctx, ImGuiSettingsHandler* handler, ImGuiTextBuffer* buf);
+}
+
+//-----------------------------------------------------------------------------
+// Docking: ImGuiDockContext
+//-----------------------------------------------------------------------------
+// The lifetime model is different from the one of regular windows: we always create a ImGuiDockNode for each ImGuiDockNodeSettings,
+// or we always hold the entire docking node tree. Nodes are frequently hidden, e.g. if the window(s) or child nodes they host are not active.
+// At boot time only, we run a simple GC to remove nodes that have no references.
+// Because dock node settings (which are small, contiguous structures) are always mirrored by their corresponding dock nodes (more complete structures),
+// we can also very easily recreate the nodes from scratch given the settings data (this is what DockContextRebuild() does).
+// This is convenient as docking reconfiguration can be implemented by mostly poking at the simpler settings data.
+//-----------------------------------------------------------------------------
+// - DockContextInitialize()
+// - DockContextShutdown()
+// - DockContextClearNodes()
+// - DockContextRebuildNodes()
+// - DockContextNewFrameUpdateUndocking()
+// - DockContextNewFrameUpdateDocking()
+// - DockContextEndFrame()
+// - DockContextFindNodeByID()
+// - DockContextBindNodeToWindow()
+// - DockContextGenNodeID()
+// - DockContextAddNode()
+// - DockContextRemoveNode()
+// - ImGuiDockContextPruneNodeData
+// - DockContextPruneUnusedSettingsNodes()
+// - DockContextBuildNodesFromSettings()
+// - DockContextBuildAddWindowsToNodes()
+//-----------------------------------------------------------------------------
+
+void ImGui::DockContextInitialize(ImGuiContext* ctx)
+{
+    ImGuiContext& g = *ctx;
+
+    // Add .ini handle for persistent docking data
+    ImGuiSettingsHandler ini_handler;
+    ini_handler.TypeName = "Docking";
+    ini_handler.TypeHash = ImHashStr("Docking");
+    ini_handler.ClearAllFn = DockSettingsHandler_ClearAll;
+    ini_handler.ReadInitFn = DockSettingsHandler_ClearAll; // Also clear on read
+    ini_handler.ReadOpenFn = DockSettingsHandler_ReadOpen;
+    ini_handler.ReadLineFn = DockSettingsHandler_ReadLine;
+    ini_handler.ApplyAllFn = DockSettingsHandler_ApplyAll;
+    ini_handler.WriteAllFn = DockSettingsHandler_WriteAll;
+    g.SettingsHandlers.push_back(ini_handler);
+
+    g.DockNodeWindowMenuHandler = &DockNodeWindowMenuHandler_Default;
+}
+
+void ImGui::DockContextShutdown(ImGuiContext* ctx)
+{
+    ImGuiDockContext* dc = &ctx->DockContext;
+    for (int n = 0; n < dc->Nodes.Data.Size; n++)
+        if (ImGuiDockNode* node = (ImGuiDockNode*)dc->Nodes.Data[n].val_p)
+            DockContextDeleteNode(ctx, node);
+}
+
+void ImGui::DockContextClearNodes(ImGuiContext* ctx, ImGuiID root_id, bool clear_settings_refs)
+{
+    IM_UNUSED(ctx);
+    IM_ASSERT(ctx == GImGui);
+    DockBuilderRemoveNodeDockedWindows(root_id, clear_settings_refs);
+    DockBuilderRemoveNodeChildNodes(root_id);
+}
+
+// [DEBUG] This function also acts as a defacto test to make sure we can rebuild from scratch without a glitch
+// (Different from DockSettingsHandler_ClearAll() + DockSettingsHandler_ApplyAll() because this reuses current settings!)
+void ImGui::DockContextRebuildNodes(ImGuiContext* ctx)
+{
+    ImGuiContext& g = *ctx;
+    ImGuiDockContext* dc = &ctx->DockContext;
+    IMGUI_DEBUG_LOG_DOCKING("[docking] DockContextRebuildNodes\n");
+    SaveIniSettingsToMemory();
+    ImGuiID root_id = 0; // Rebuild all
+    DockContextClearNodes(ctx, root_id, false);
+    DockContextBuildNodesFromSettings(ctx, dc->NodesSettings.Data, dc->NodesSettings.Size);
+    DockContextBuildAddWindowsToNodes(ctx, root_id);
+}
+
+// Docking context update function, called by NewFrame()
+void ImGui::DockContextNewFrameUpdateUndocking(ImGuiContext* ctx)
+{
+    ImGuiContext& g = *ctx;
+    ImGuiDockContext* dc = &ctx->DockContext;
+    if (!(g.IO.ConfigFlags & ImGuiConfigFlags_DockingEnable))
+    {
+        if (dc->Nodes.Data.Size > 0 || dc->Requests.Size > 0)
+            DockContextClearNodes(ctx, 0, true);
+        return;
+    }
+
+    // Setting NoSplit at runtime merges all nodes
+    if (g.IO.ConfigDockingNoSplit)
+        for (int n = 0; n < dc->Nodes.Data.Size; n++)
+            if (ImGuiDockNode* node = (ImGuiDockNode*)dc->Nodes.Data[n].val_p)
+                if (node->IsRootNode() && node->IsSplitNode())
+                {
+                    DockBuilderRemoveNodeChildNodes(node->ID);
+                    //dc->WantFullRebuild = true;
+                }
+
+    // Process full rebuild
+#if 0
+    if (ImGui::IsKeyPressed(ImGui::GetKeyIndex(ImGuiKey_C)))
+        dc->WantFullRebuild = true;
+#endif
+    if (dc->WantFullRebuild)
+    {
+        DockContextRebuildNodes(ctx);
+        dc->WantFullRebuild = false;
+    }
+
+    // Process Undocking requests (we need to process them _before_ the UpdateMouseMovingWindowNewFrame call in NewFrame)
+    for (ImGuiDockRequest& req : dc->Requests)
+    {
+        if (req.Type == ImGuiDockRequestType_Undock && req.UndockTargetWindow)
+            DockContextProcessUndockWindow(ctx, req.UndockTargetWindow);
+        else if (req.Type == ImGuiDockRequestType_Undock && req.UndockTargetNode)
+            DockContextProcessUndockNode(ctx, req.UndockTargetNode);
+    }
+}
+
+// Docking context update function, called by NewFrame()
+void ImGui::DockContextNewFrameUpdateDocking(ImGuiContext* ctx)
+{
+    ImGuiContext& g = *ctx;
+    ImGuiDockContext* dc = &ctx->DockContext;
+    if (!(g.IO.ConfigFlags & ImGuiConfigFlags_DockingEnable))
+        return;
+
+    // [DEBUG] Store hovered dock node.
+    // We could in theory use DockNodeTreeFindVisibleNodeByPos() on the root host dock node, but using ->DockNode is a good shortcut.
+    // Note this is mostly a debug thing and isn't actually used for docking target, because docking involve more detailed filtering.
+    g.DebugHoveredDockNode = NULL;
+    if (ImGuiWindow* hovered_window = g.HoveredWindowUnderMovingWindow)
+    {
+        if (hovered_window->DockNodeAsHost)
+            g.DebugHoveredDockNode = DockNodeTreeFindVisibleNodeByPos(hovered_window->DockNodeAsHost, g.IO.MousePos);
+        else if (hovered_window->RootWindow->DockNode)
+            g.DebugHoveredDockNode = hovered_window->RootWindow->DockNode;
+    }
+
+    // Process Docking requests
+    for (ImGuiDockRequest& req : dc->Requests)
+        if (req.Type == ImGuiDockRequestType_Dock)
+            DockContextProcessDock(ctx, &req);
+    dc->Requests.resize(0);
+
+    // Create windows for each automatic docking nodes
+    // We can have NULL pointers when we delete nodes, but because ID are recycled this should amortize nicely (and our node count will never be very high)
+    for (int n = 0; n < dc->Nodes.Data.Size; n++)
+        if (ImGuiDockNode* node = (ImGuiDockNode*)dc->Nodes.Data[n].val_p)
+            if (node->IsFloatingNode())
+                DockNodeUpdate(node);
+}
+
+void ImGui::DockContextEndFrame(ImGuiContext* ctx)
+{
+    // Draw backgrounds of node missing their window
+    ImGuiContext& g = *ctx;
+    ImGuiDockContext* dc = &g.DockContext;
+    for (int n = 0; n < dc->Nodes.Data.Size; n++)
+        if (ImGuiDockNode* node = (ImGuiDockNode*)dc->Nodes.Data[n].val_p)
+            if (node->LastFrameActive == g.FrameCount && node->IsVisible && node->HostWindow && node->IsLeafNode() && !node->IsBgDrawnThisFrame)
+            {
+                ImRect bg_rect(node->Pos + ImVec2(0.0f, GetFrameHeight()), node->Pos + node->Size);
+                ImDrawFlags bg_rounding_flags = CalcRoundingFlagsForRectInRect(bg_rect, node->HostWindow->Rect(), g.Style.DockingSeparatorSize);
+                node->HostWindow->DrawList->ChannelsSetCurrent(DOCKING_HOST_DRAW_CHANNEL_BG);
+                node->HostWindow->DrawList->AddRectFilled(bg_rect.Min, bg_rect.Max, node->LastBgColor, node->HostWindow->WindowRounding, bg_rounding_flags);
+            }
+}
+
+ImGuiDockNode* ImGui::DockContextFindNodeByID(ImGuiContext* ctx, ImGuiID id)
+{
+    return (ImGuiDockNode*)ctx->DockContext.Nodes.GetVoidPtr(id);
+}
+
+ImGuiID ImGui::DockContextGenNodeID(ImGuiContext* ctx)
+{
+    // Generate an ID for new node (the exact ID value doesn't matter as long as it is not already used)
+    // FIXME-OPT FIXME-DOCK: This is suboptimal, even if the node count is small enough not to be a worry.0
+    // We should poke in ctx->Nodes to find a suitable ID faster. Even more so trivial that ctx->Nodes lookup is already sorted.
+    ImGuiID id = 0x0001;
+    while (DockContextFindNodeByID(ctx, id) != NULL)
+        id++;
+    return id;
+}
+
+static ImGuiDockNode* ImGui::DockContextAddNode(ImGuiContext* ctx, ImGuiID id)
+{
+    // Generate an ID for the new node (the exact ID value doesn't matter as long as it is not already used) and add the first window.
+    ImGuiContext& g = *ctx;
+    if (id == 0)
+        id = DockContextGenNodeID(ctx);
+    else
+        IM_ASSERT(DockContextFindNodeByID(ctx, id) == NULL);
+
+    // We don't set node->LastFrameAlive on construction. Nodes are always created at all time to reflect .ini settings!
+    IMGUI_DEBUG_LOG_DOCKING("[docking] DockContextAddNode 0x%08X\n", id);
+    ImGuiDockNode* node = IM_NEW(ImGuiDockNode)(id);
+    ctx->DockContext.Nodes.SetVoidPtr(node->ID, node);
+    return node;
+}
+
+static void ImGui::DockContextRemoveNode(ImGuiContext* ctx, ImGuiDockNode* node, bool merge_sibling_into_parent_node)
+{
+    ImGuiContext& g = *ctx;
+
+    IMGUI_DEBUG_LOG_DOCKING("[docking] DockContextRemoveNode 0x%08X\n", node->ID);
+    IM_ASSERT(DockContextFindNodeByID(ctx, node->ID) == node);
+    IM_ASSERT(node->ChildNodes[0] == NULL && node->ChildNodes[1] == NULL);
+    IM_ASSERT(node->Windows.Size == 0);
+
+    if (node->HostWindow)
+        node->HostWindow->DockNodeAsHost = NULL;
+
+    ImGuiDockNode* parent_node = node->ParentNode;
+    const bool merge = (merge_sibling_into_parent_node && parent_node != NULL);
+    if (merge)
+    {
+        IM_ASSERT(parent_node->ChildNodes[0] == node || parent_node->ChildNodes[1] == node);
+        ImGuiDockNode* sibling_node = (parent_node->ChildNodes[0] == node ? parent_node->ChildNodes[1] : parent_node->ChildNodes[0]);
+        DockNodeTreeMerge(&g, parent_node, sibling_node);
+    }
+    else
+    {
+        for (int n = 0; parent_node && n < IM_COUNTOF(parent_node->ChildNodes); n++)
+            if (parent_node->ChildNodes[n] == node)
+                node->ParentNode->ChildNodes[n] = NULL;
+        DockContextDeleteNode(ctx, node);
+    }
+}
+
+// Raw-ish delete
+static void ImGui::DockContextDeleteNode(ImGuiContext* ctx, ImGuiDockNode* node)
+{
+    ImGuiDockContext* dc = &ctx->DockContext;
+    if (node->TabBar)
+        IM_DELETE(node->TabBar);
+    node->TabBar = NULL;
+    dc->Nodes.SetVoidPtr(node->ID, NULL);
+    IM_DELETE(node);
+}
+
+static int IMGUI_CDECL DockNodeComparerDepthMostFirst(const void* lhs, const void* rhs)
+{
+    const ImGuiDockNode* a = *(const ImGuiDockNode* const*)lhs;
+    const ImGuiDockNode* b = *(const ImGuiDockNode* const*)rhs;
+    return ImGui::DockNodeGetDepth(b) - ImGui::DockNodeGetDepth(a);
+}
+
+// Pre C++0x doesn't allow us to use a function-local type (without linkage) as template parameter, so we moved this here.
+struct ImGuiDockContextPruneNodeData
+{
+    int         CountWindows, CountChildWindows, CountChildNodes;
+    ImGuiID     RootId;
+    ImGuiDockContextPruneNodeData() { CountWindows = CountChildWindows = CountChildNodes = 0; RootId = 0; }
+};
+
+// Garbage collect unused nodes (run once at init time)
+static void ImGui::DockContextPruneUnusedSettingsNodes(ImGuiContext* ctx)
+{
+    ImGuiContext& g = *ctx;
+    ImGuiDockContext* dc = &ctx->DockContext;
+    IM_ASSERT(g.Windows.Size == 0);
+
+    ImPool<ImGuiDockContextPruneNodeData> pool;
+    pool.Reserve(dc->NodesSettings.Size);
+
+    // Count child nodes and compute RootID
+    for (int settings_n = 0; settings_n < dc->NodesSettings.Size; settings_n++)
+    {
+        ImGuiDockNodeSettings* settings = &dc->NodesSettings[settings_n];
+        if (pool.GetByKey(settings->ID) != 0)
+        {
+            settings->ID = 0; // Duplicate
+            continue;
+        }
+        ImGuiDockContextPruneNodeData* parent_data = settings->ParentNodeId ? pool.GetByKey(settings->ParentNodeId) : 0;
+        pool.GetOrAddByKey(settings->ID)->RootId = parent_data ? parent_data->RootId : settings->ID;
+        if (settings->ParentNodeId)
+            pool.GetOrAddByKey(settings->ParentNodeId)->CountChildNodes++;
+    }
+
+    // Count reference to dock ids from dockspaces
+    // We track the 'auto-DockNode <- manual-Window <- manual-DockSpace' in order to avoid 'auto-DockNode' being ditched by DockContextPruneUnusedSettingsNodes()
+    for (int settings_n = 0; settings_n < dc->NodesSettings.Size; settings_n++)
+    {
+        ImGuiDockNodeSettings* settings = &dc->NodesSettings[settings_n];
+        if (settings->ParentWindowId != 0)
+            if (ImGuiWindowSettings* window_settings = FindWindowSettingsByID(settings->ParentWindowId))
+                if (window_settings->DockId)
+                    if (ImGuiDockContextPruneNodeData* data = pool.GetByKey(window_settings->DockId))
+                        data->CountChildNodes++;
+    }
+
+    // Count reference to dock ids from window settings
+    // We guard against the possibility of an invalid .ini file (RootID may point to a missing node)
+    for (ImGuiWindowSettings* settings = g.SettingsWindows.begin(); settings != NULL; settings = g.SettingsWindows.next_chunk(settings))
+        if (ImGuiID dock_id = settings->DockId)
+            if (ImGuiDockContextPruneNodeData* data = pool.GetByKey(dock_id))
+            {
+                data->CountWindows++;
+                if (ImGuiDockContextPruneNodeData* data_root = (data->RootId == dock_id) ? data : pool.GetByKey(data->RootId))
+                    data_root->CountChildWindows++;
+            }
+
+    // Prune
+    for (int settings_n = 0; settings_n < dc->NodesSettings.Size; settings_n++)
+    {
+        ImGuiDockNodeSettings* settings = &dc->NodesSettings[settings_n];
+        ImGuiDockContextPruneNodeData* data = pool.GetByKey(settings->ID);
+        if (data == NULL || data->CountWindows > 1)
+            continue;
+        ImGuiDockContextPruneNodeData* data_root = (settings->ID == data->RootId) ? data : pool.GetByKey(data->RootId);
+        ImGuiDockContextPruneNodeData* data_parent = settings->ParentNodeId ? pool.GetByKey(settings->ParentNodeId) : NULL;
+
+        bool remove = false;
+        remove |= (data->CountWindows == 1 && settings->ParentNodeId == 0 && data->CountChildNodes == 0 && !(settings->Flags & ImGuiDockNodeFlags_CentralNode));  // Floating root node with only 1 window
+        remove |= (data->CountWindows == 0 && settings->ParentNodeId == 0 && data->CountChildNodes == 0); // Leaf nodes with 0 window
+        remove |= (data_root == NULL || data_root->CountChildWindows == 0);
+        if (remove)
+        {
+            IMGUI_DEBUG_LOG_DOCKING("[docking] DockContextPruneUnusedSettingsNodes: Prune 0x%08X\n", settings->ID);
+            DockSettingsRemoveNodeReferences(&settings->ID, 1);
+            settings->ID = 0;
+        }
+        else if (data_parent && data_parent->CountChildNodes == 1)
+        {
+            IMGUI_DEBUG_LOG_DOCKING("[docking] DockContextPruneUnusedSettingsNodes: Merge 0x%08X->0X%08X\n", settings->ID, settings->ParentNodeId);
+            DockSettingsRenameNodeReferences(settings->ID, settings->ParentNodeId);
+            settings->ID = 0;
+        }
+    }
+}
+
+static void ImGui::DockContextBuildNodesFromSettings(ImGuiContext* ctx, ImGuiDockNodeSettings* node_settings_array, int node_settings_count)
+{
+    // Build nodes
+    ImGuiContext& g = *ctx; IM_UNUSED(g);
+    for (int node_n = 0; node_n < node_settings_count; node_n++)
+    {
+        ImGuiDockNodeSettings* settings = &node_settings_array[node_n];
+        if (settings->ID == 0)
+            continue;
+        if (DockContextFindNodeByID(ctx, settings->ID) != NULL)
+        {
+            IMGUI_DEBUG_LOG_DOCKING("[docking] DockContextBuildNodesFromSettings: skip duplicate node 0x%08X\n", settings->ID);
+            continue;
+        }
+        ImGuiDockNode* node = DockContextAddNode(ctx, settings->ID);
+        node->ParentNode = settings->ParentNodeId ? DockContextFindNodeByID(ctx, settings->ParentNodeId) : NULL;
+        node->Pos = ImVec2(settings->Pos.x, settings->Pos.y);
+        node->Size = ImVec2(settings->Size.x, settings->Size.y);
+        node->SizeRef = ImVec2(settings->SizeRef.x, settings->SizeRef.y);
+        node->AuthorityForPos = node->AuthorityForSize = node->AuthorityForViewport = ImGuiDataAuthority_DockNode;
+        if (node->ParentNode && node->ParentNode->ChildNodes[0] == NULL)
+            node->ParentNode->ChildNodes[0] = node;
+        else if (node->ParentNode && node->ParentNode->ChildNodes[1] == NULL)
+            node->ParentNode->ChildNodes[1] = node;
+        node->SelectedTabId = settings->SelectedTabId;
+        node->SplitAxis = (ImGuiAxis)settings->SplitAxis;
+        node->SetLocalFlags(settings->Flags & ImGuiDockNodeFlags_SavedFlagsMask_);
+
+        // Bind host window immediately if it already exist (in case of a rebuild)
+        // This is useful as the RootWindowForTitleBarHighlight links necessary to highlight the currently focused node requires node->HostWindow to be set.
+        char host_window_title[20];
+        ImGuiDockNode* root_node = DockNodeGetRootNode(node);
+        node->HostWindow = FindWindowByName(DockNodeGetHostWindowTitle(root_node, host_window_title, IM_COUNTOF(host_window_title)));
+    }
+}
+
+void ImGui::DockContextBuildAddWindowsToNodes(ImGuiContext* ctx, ImGuiID root_id)
+{
+    // Rebind all windows to nodes (they can also lazily rebind but we'll have a visible glitch during the first frame)
+    ImGuiContext& g = *ctx;
+    for (ImGuiWindow* window : g.Windows)
+    {
+        if (window->DockId == 0 || window->LastFrameActive < g.FrameCount - 1)
+            continue;
+        if (window->DockNode != NULL)
+            continue;
+
+        ImGuiDockNode* node = DockContextFindNodeByID(ctx, window->DockId);
+        IM_ASSERT(node != NULL);   // This should have been called after DockContextBuildNodesFromSettings()
+        if (root_id == 0 || DockNodeGetRootNode(node)->ID == root_id)
+            DockNodeAddWindow(node, window, true);
+    }
+}
+
+//-----------------------------------------------------------------------------
+// Docking: ImGuiDockContext Docking/Undocking functions
+//-----------------------------------------------------------------------------
+// - DockContextQueueDock()
+// - DockContextQueueUndockWindow()
+// - DockContextQueueUndockNode()
+// - DockContextQueueNotifyRemovedNode()
+// - DockContextProcessDock()
+// - DockContextProcessUndockWindow()
+// - DockContextProcessUndockNode()
+// - DockContextCalcDropPosForDocking()
+//-----------------------------------------------------------------------------
+
+void ImGui::DockContextQueueDock(ImGuiContext* ctx, ImGuiWindow* target, ImGuiDockNode* target_node, ImGuiWindow* payload, ImGuiDir split_dir, float split_ratio, bool split_outer)
+{
+    IM_ASSERT(target != payload);
+    ImGuiDockRequest req;
+    req.Type = ImGuiDockRequestType_Dock;
+    req.DockTargetWindow = target;
+    req.DockTargetNode = target_node;
+    req.DockPayload = payload;
+    req.DockSplitDir = split_dir;
+    req.DockSplitRatio = split_ratio;
+    req.DockSplitOuter = split_outer;
+    ctx->DockContext.Requests.push_back(req);
+}
+
+void ImGui::DockContextQueueUndockWindow(ImGuiContext* ctx, ImGuiWindow* window)
+{
+    ImGuiDockRequest req;
+    req.Type = ImGuiDockRequestType_Undock;
+    req.UndockTargetWindow = window;
+    ctx->DockContext.Requests.push_back(req);
+}
+
+void ImGui::DockContextQueueUndockNode(ImGuiContext* ctx, ImGuiDockNode* node)
+{
+    ImGuiDockRequest req;
+    req.Type = ImGuiDockRequestType_Undock;
+    req.UndockTargetNode = node;
+    ctx->DockContext.Requests.push_back(req);
+}
+
+void ImGui::DockContextQueueNotifyRemovedNode(ImGuiContext* ctx, ImGuiDockNode* node)
+{
+    ImGuiDockContext* dc = &ctx->DockContext;
+    for (ImGuiDockRequest& req : dc->Requests)
+        if (req.DockTargetNode == node)
+            req.Type = ImGuiDockRequestType_None;
+}
+
+void ImGui::DockContextProcessDock(ImGuiContext* ctx, ImGuiDockRequest* req)
+{
+    IM_ASSERT((req->Type == ImGuiDockRequestType_Dock && req->DockPayload != NULL) || (req->Type == ImGuiDockRequestType_Split && req->DockPayload == NULL));
+    IM_ASSERT(req->DockTargetWindow != NULL || req->DockTargetNode != NULL);
+
+    ImGuiContext& g = *ctx;
+    IM_UNUSED(g);
+
+    ImGuiWindow* payload_window = req->DockPayload;     // Optional
+    ImGuiWindow* target_window = req->DockTargetWindow;
+    ImGuiDockNode* node = req->DockTargetNode;
+    if (payload_window)
+        IMGUI_DEBUG_LOG_DOCKING("[docking] DockContextProcessDock node 0x%08X target '%s' dock window '%s', split_dir %d\n", node ? node->ID : 0, target_window ? target_window->Name : "NULL", payload_window->Name, req->DockSplitDir);
+    else
+        IMGUI_DEBUG_LOG_DOCKING("[docking] DockContextProcessDock node 0x%08X, split_dir %d\n", node ? node->ID : 0, req->DockSplitDir);
+
+    // Decide which Tab will be selected at the end of the operation
+    ImGuiID next_selected_id = 0;
+    ImGuiDockNode* payload_node = NULL;
+    if (payload_window)
+    {
+        payload_node = payload_window->DockNodeAsHost;
+        payload_window->DockNodeAsHost = NULL; // Important to clear this as the node will have its life as a child which might be merged/deleted later.
+        if (payload_node && payload_node->IsLeafNode())
+            next_selected_id = payload_node->TabBar->NextSelectedTabId ? payload_node->TabBar->NextSelectedTabId : payload_node->TabBar->SelectedTabId;
+        if (payload_node == NULL)
+            next_selected_id = payload_window->TabId;
+    }
+
+    // FIXME-DOCK: When we are trying to dock an existing single-window node into a loose window, transfer Node ID as well
+    // When processing an interactive split, usually LastFrameAlive will be < g.FrameCount. But DockBuilder operations can make it ==.
+    if (node)
+        IM_ASSERT(node->LastFrameAlive <= g.FrameCount);
+    if (node && target_window && node == target_window->DockNodeAsHost)
+        IM_ASSERT(node->Windows.Size > 0 || node->IsSplitNode() || node->IsCentralNode());
+
+    // Create new node and add existing window to it
+    if (node == NULL)
+    {
+        node = DockContextAddNode(ctx, 0);
+        node->Pos = target_window->Pos;
+        node->Size = target_window->Size;
+        if (target_window->DockNodeAsHost == NULL)
+        {
+            DockNodeAddWindow(node, target_window, true);
+            node->TabBar->Tabs[0].Flags &= ~ImGuiTabItemFlags_Unsorted;
+            target_window->DockIsActive = true;
+        }
+    }
+
+    ImGuiDir split_dir = req->DockSplitDir;
+    if (split_dir != ImGuiDir_None)
+    {
+        // Split into two, one side will be our payload node unless we are dropping a loose window
+        const ImGuiAxis split_axis = (split_dir == ImGuiDir_Left || split_dir == ImGuiDir_Right) ? ImGuiAxis_X : ImGuiAxis_Y;
+        const int split_inheritor_child_idx = (split_dir == ImGuiDir_Left || split_dir == ImGuiDir_Up) ? 1 : 0; // Current contents will be moved to the opposite side
+        const float split_ratio = req->DockSplitRatio;
+        DockNodeTreeSplit(ctx, node, split_axis, split_inheritor_child_idx, split_ratio, payload_node);  // payload_node may be NULL here!
+        ImGuiDockNode* new_node = node->ChildNodes[split_inheritor_child_idx ^ 1];
+        new_node->HostWindow = node->HostWindow;
+        node = new_node;
+    }
+    node->SetLocalFlags(node->LocalFlags & ~ImGuiDockNodeFlags_HiddenTabBar);
+
+    if (node != payload_node)
+    {
+        // Create tab bar before we call DockNodeMoveWindows (which would attempt to move the old tab-bar, which would lead us to payload tabs wrongly appearing before target tabs!)
+        if (node->Windows.Size > 0 && node->TabBar == NULL)
+        {
+            DockNodeAddTabBar(node);
+            for (int n = 0; n < node->Windows.Size; n++)
+                TabBarAddTab(node->TabBar, ImGuiTabItemFlags_None, node->Windows[n]);
+        }
+
+        if (payload_node != NULL)
+        {
+            // Transfer full payload node (with 1+ child windows or child nodes)
+            if (payload_node->IsSplitNode())
+            {
+                if (node->Windows.Size > 0)
+                {
+                    // We can dock a split payload into a node that already has windows _only_ if our payload is a node tree with a single visible node.
+                    // In this situation, we move the windows of the target node into the currently visible node of the payload.
+                    // This allows us to preserve some of the underlying dock tree settings nicely.
+                    IM_ASSERT(payload_node->OnlyNodeWithWindows != NULL); // The docking should have been blocked by DockNodePreviewDockSetup() early on and never submitted.
+                    ImGuiDockNode* visible_node = payload_node->OnlyNodeWithWindows;
+                    if (visible_node->TabBar)
+                        IM_ASSERT(visible_node->TabBar->Tabs.Size > 0);
+                    DockNodeMoveWindows(node, visible_node);
+                    DockNodeMoveWindows(visible_node, node);
+                    DockSettingsRenameNodeReferences(node->ID, visible_node->ID);
+                }
+                if (node->IsCentralNode())
+                {
+                    // Central node property needs to be moved to a leaf node, pick the last focused one.
+                    // FIXME-DOCK: If we had to transfer other flags here, what would the policy be?
+                    ImGuiDockNode* last_focused_node = DockContextFindNodeByID(ctx, payload_node->LastFocusedNodeId);
+                    IM_ASSERT(last_focused_node != NULL);
+                    ImGuiDockNode* last_focused_root_node = DockNodeGetRootNode(last_focused_node);
+                    IM_ASSERT(last_focused_root_node == DockNodeGetRootNode(payload_node));
+                    last_focused_node->SetLocalFlags(last_focused_node->LocalFlags | ImGuiDockNodeFlags_CentralNode);
+                    node->SetLocalFlags(node->LocalFlags & ~ImGuiDockNodeFlags_CentralNode);
+                    last_focused_root_node->CentralNode = last_focused_node;
+                }
+
+                IM_ASSERT(node->Windows.Size == 0);
+                DockNodeMoveChildNodes(node, payload_node);
+            }
+            else
+            {
+                const ImGuiID payload_dock_id = payload_node->ID;
+                DockNodeMoveWindows(node, payload_node);
+                DockSettingsRenameNodeReferences(payload_dock_id, node->ID);
+            }
+            DockContextRemoveNode(ctx, payload_node, true);
+        }
+        else if (payload_window)
+        {
+            // Transfer single window
+            const ImGuiID payload_dock_id = payload_window->DockId;
+            node->VisibleWindow = payload_window;
+            DockNodeAddWindow(node, payload_window, true);
+            if (payload_dock_id != 0)
+                DockSettingsRenameNodeReferences(payload_dock_id, node->ID);
+        }
+    }
+    else
+    {
+        // When docking a floating single window node we want to reevaluate auto-hiding of the tab bar
+        node->WantHiddenTabBarUpdate = true;
+    }
+
+    // Update selection immediately
+    if (ImGuiTabBar* tab_bar = node->TabBar)
+        tab_bar->NextSelectedTabId = next_selected_id;
+    MarkIniSettingsDirty();
+}
+
+// Problem:
+//   Undocking a large (~full screen) window would leave it so large that the bottom right sizing corner would more
+//   than likely be off the screen and the window would be hard to resize to fit on screen. This can be particularly problematic
+//   with 'ConfigWindowsMoveFromTitleBarOnly=true' and/or with 'ConfigWindowsResizeFromEdges=false' as well (the later can be
+//   due to missing ImGuiBackendFlags_HasMouseCursors backend flag).
+// Solution:
+//   When undocking a window we currently force its maximum size to 90% of the host viewport or monitor.
+// Reevaluate this when we implement preserving docked/undocked size ("docking_wip/undocked_size" branch).
+static ImVec2 FixLargeWindowsWhenUndocking(const ImVec2& size, ImGuiViewport* ref_viewport)
+{
+    if (ref_viewport == NULL)
+        return size;
+
+    ImGuiContext& g = *GImGui;
+    ImVec2 max_size = ImTrunc(ref_viewport->WorkSize * 0.90f);
+    if (g.ConfigFlagsCurrFrame & ImGuiConfigFlags_ViewportsEnable)
+    {
+        const ImGuiPlatformMonitor* monitor = ImGui::GetViewportPlatformMonitor(ref_viewport);
+        max_size = ImTrunc(monitor->WorkSize * 0.90f);
+    }
+    return ImMin(size, max_size);
+}
+
+void ImGui::DockContextProcessUndockWindow(ImGuiContext* ctx, ImGuiWindow* window, bool clear_persistent_docking_ref)
+{
+    ImGuiContext& g = *ctx;
+    IMGUI_DEBUG_LOG_DOCKING("[docking] DockContextProcessUndockWindow window '%s', clear_persistent_docking_ref = %d\n", window->Name, clear_persistent_docking_ref);
+    if (window->DockNode)
+        DockNodeRemoveWindow(window->DockNode, window, clear_persistent_docking_ref ? 0 : window->DockId);
+    else
+        window->DockId = 0;
+    window->Collapsed = false;
+    window->DockIsActive = false;
+    window->DockNodeIsVisible = window->DockTabIsVisible = false;
+    window->Size = window->SizeFull = FixLargeWindowsWhenUndocking(window->SizeFull, window->Viewport);
+
+    MarkIniSettingsDirty();
+}
+
+void ImGui::DockContextProcessUndockNode(ImGuiContext* ctx, ImGuiDockNode* node)
+{
+    ImGuiContext& g = *ctx;
+    IMGUI_DEBUG_LOG_DOCKING("[docking] DockContextProcessUndockNode node %08X\n", node->ID);
+    IM_ASSERT(node->IsLeafNode());
+    IM_ASSERT(node->Windows.Size >= 1);
+
+    if (node->IsRootNode() || node->IsCentralNode())
+    {
+        // In the case of a root node or central node, the node will have to stay in place. Create a new node to receive the payload.
+        ImGuiDockNode* new_node = DockContextAddNode(ctx, 0);
+        new_node->Pos = node->Pos;
+        new_node->Size = node->Size;
+        new_node->SizeRef = node->SizeRef;
+        DockNodeMoveWindows(new_node, node);
+        DockSettingsRenameNodeReferences(node->ID, new_node->ID);
+        node = new_node;
+    }
+    else
+    {
+        // Otherwise extract our node and merge our sibling back into the parent node.
+        IM_ASSERT(node->ParentNode->ChildNodes[0] == node || node->ParentNode->ChildNodes[1] == node);
+        int index_in_parent = (node->ParentNode->ChildNodes[0] == node) ? 0 : 1;
+        node->ParentNode->ChildNodes[index_in_parent] = NULL;
+        DockNodeTreeMerge(ctx, node->ParentNode, node->ParentNode->ChildNodes[index_in_parent ^ 1]);
+        node->ParentNode->AuthorityForViewport = ImGuiDataAuthority_Window; // The node that stays in place keeps the viewport, so our newly dragged out node will create a new viewport
+        node->ParentNode = NULL;
+    }
+    for (ImGuiWindow* window : node->Windows)
+    {
+        window->Flags &= ~ImGuiWindowFlags_ChildWindow;
+        if (window->ParentWindow)
+            window->ParentWindow->DC.ChildWindows.find_erase(window);
+        UpdateWindowParentAndRootLinks(window, window->Flags, NULL);
+    }
+    node->AuthorityForPos = node->AuthorityForSize = ImGuiDataAuthority_DockNode;
+    node->Size = FixLargeWindowsWhenUndocking(node->Size, node->Windows[0]->Viewport);
+    node->WantMouseMove = true;
+    MarkIniSettingsDirty();
+}
+
+// This is mostly used for automation.
+bool ImGui::DockContextCalcDropPosForDocking(ImGuiWindow* target, ImGuiDockNode* target_node, ImGuiWindow* payload_window, ImGuiDockNode* payload_node, ImGuiDir split_dir, bool split_outer, ImVec2* out_pos)
+{
+    if (target != NULL && target_node == NULL)
+        target_node = target->DockNode;
+
+    // In DockNodePreviewDockSetup() for a root central node instead of showing both "inner" and "outer" drop rects
+    // (which would be functionally identical) we only show the outer one. Reflect this here.
+    if (target_node && target_node->ParentNode == NULL && target_node->IsCentralNode() && split_dir != ImGuiDir_None)
+        split_outer = true;
+    ImGuiDockPreviewData split_data;
+    DockNodePreviewDockSetup(target, target_node, payload_window, payload_node, &split_data, false, split_outer);
+    if (split_data.DropRectsDraw[split_dir+1].IsInverted())
+        return false;
+    *out_pos = split_data.DropRectsDraw[split_dir+1].GetCenter();
+    return true;
+}
+
+//-----------------------------------------------------------------------------
+// Docking: ImGuiDockNode
+//-----------------------------------------------------------------------------
+// - DockNodeGetTabOrder()
+// - DockNodeAddWindow()
+// - DockNodeRemoveWindow()
+// - DockNodeMoveChildNodes()
+// - DockNodeMoveWindows()
+// - DockNodeApplyPosSizeToWindows()
+// - DockNodeHideHostWindow()
+// - ImGuiDockNodeFindInfoResults
+// - DockNodeFindInfo()
+// - DockNodeFindWindowByID()
+// - DockNodeUpdateFlagsAndCollapse()
+// - DockNodeUpdateHasCentralNodeFlag()
+// - DockNodeUpdateVisibleFlag()
+// - DockNodeStartMouseMovingWindow()
+// - DockNodeUpdate()
+// - DockNodeUpdateWindowMenu()
+// - DockNodeBeginAmendTabBar()
+// - DockNodeEndAmendTabBar()
+// - DockNodeUpdateTabBar()
+// - DockNodeAddTabBar()
+// - DockNodeRemoveTabBar()
+// - DockNodeIsDropAllowedOne()
+// - DockNodeIsDropAllowed()
+// - DockNodeCalcTabBarLayout()
+// - DockNodeCalcSplitRects()
+// - DockNodeCalcDropRectsAndTestMousePos()
+// - DockNodePreviewDockSetup()
+// - DockNodePreviewDockRender()
+//-----------------------------------------------------------------------------
+
+ImGuiDockNode::ImGuiDockNode(ImGuiID id)
+{
+    ID = id;
+    SharedFlags = LocalFlags = LocalFlagsInWindows = MergedFlags = ImGuiDockNodeFlags_None;
+    ParentNode = ChildNodes[0] = ChildNodes[1] = NULL;
+    TabBar = NULL;
+    SplitAxis = ImGuiAxis_None;
+
+    State = ImGuiDockNodeState_Unknown;
+    LastBgColor = IM_COL32_WHITE;
+    HostWindow = VisibleWindow = NULL;
+    CentralNode = OnlyNodeWithWindows = NULL;
+    CountNodeWithWindows = 0;
+    LastFrameAlive = LastFrameActive = LastFrameFocused = -1;
+    LastFocusedNodeId = 0;
+    SelectedTabId = 0;
+    WantCloseTabId = 0;
+    RefViewportId = 0;
+    AuthorityForPos = AuthorityForSize = ImGuiDataAuthority_DockNode;
+    AuthorityForViewport = ImGuiDataAuthority_Auto;
+    IsVisible = true;
+    IsFocused = HasCloseButton = HasWindowMenuButton = HasCentralNodeChild = false;
+    IsBgDrawnThisFrame = false;
+    WantCloseAll = WantLockSizeOnce = WantMouseMove = WantHiddenTabBarUpdate = WantHiddenTabBarToggle = false;
+}
+
+ImGuiDockNode::~ImGuiDockNode()
+{
+    IM_ASSERT(TabBar == NULL);
+    ChildNodes[0] = ChildNodes[1] = NULL;
+}
+
+int ImGui::DockNodeGetTabOrder(ImGuiWindow* window)
+{
+    ImGuiTabBar* tab_bar = window->DockNode->TabBar;
+    if (tab_bar == NULL)
+        return -1;
+    ImGuiTabItem* tab = TabBarFindTabByID(tab_bar, window->TabId);
+    return tab ? TabBarGetTabOrder(tab_bar, tab) : -1;
+}
+
+static void DockNodeHideWindowDuringHostWindowCreation(ImGuiWindow* window)
+{
+    window->Hidden = true;
+    window->HiddenFramesCanSkipItems = window->Active ? 1 : 2;
+}
+
+static void ImGui::DockNodeAddWindow(ImGuiDockNode* node, ImGuiWindow* window, bool add_to_tab_bar)
+{
+    ImGuiContext& g = *GImGui; (void)g;
+    if (window->DockNode)
+    {
+        // Can overwrite an existing window->DockNode (e.g. pointing to a disabled DockSpace node)
+        IM_ASSERT(window->DockNode->ID != node->ID);
+        DockNodeRemoveWindow(window->DockNode, window, 0);
+    }
+    IM_ASSERT(window->DockNode == NULL || window->DockNodeAsHost == NULL);
+    IMGUI_DEBUG_LOG_DOCKING("[docking] DockNodeAddWindow node 0x%08X window '%s'\n", node->ID, window->Name);
+
+    // If more than 2 windows appeared on the same frame leading to the creation of a new hosting window,
+    // we'll hide windows until the host window is ready. Hide the 1st window after its been output (so it is not visible for one frame).
+    // We will call DockNodeHideWindowDuringHostWindowCreation() on ourselves in Begin()
+    if (node->HostWindow == NULL && node->Windows.Size == 1 && node->Windows[0]->WasActive == false)
+        DockNodeHideWindowDuringHostWindowCreation(node->Windows[0]);
+
+    node->Windows.push_back(window);
+    node->WantHiddenTabBarUpdate = true;
+    window->DockNode = node;
+    window->DockId = node->ID;
+    window->DockIsActive = (node->Windows.Size > 1);
+    window->DockTabWantClose = false;
+
+    // When reactivating a node with one or two loose window, the window pos/size/viewport are authoritative over the node storage.
+    // In particular it is important we init the viewport from the first window so we don't create two viewports and drop one.
+    if (node->HostWindow == NULL && node->IsFloatingNode())
+    {
+        if (node->AuthorityForPos == ImGuiDataAuthority_Auto)
+            node->AuthorityForPos = ImGuiDataAuthority_Window;
+        if (node->AuthorityForSize == ImGuiDataAuthority_Auto)
+            node->AuthorityForSize = ImGuiDataAuthority_Window;
+        if (node->AuthorityForViewport == ImGuiDataAuthority_Auto)
+            node->AuthorityForViewport = ImGuiDataAuthority_Window;
+    }
+
+    // Add to tab bar if requested
+    if (add_to_tab_bar)
+    {
+        if (node->TabBar == NULL)
+        {
+            DockNodeAddTabBar(node);
+            node->TabBar->SelectedTabId = node->TabBar->NextSelectedTabId = node->SelectedTabId;
+
+            // Add existing windows
+            for (int n = 0; n < node->Windows.Size - 1; n++)
+                TabBarAddTab(node->TabBar, ImGuiTabItemFlags_None, node->Windows[n]);
+        }
+        TabBarAddTab(node->TabBar, ImGuiTabItemFlags_Unsorted, window);
+    }
+
+    DockNodeUpdateVisibleFlag(node);
+
+    // Update this without waiting for the next time we Begin() in the window, so our host window will have the proper title bar color on its first frame.
+    if (node->HostWindow)
+        UpdateWindowParentAndRootLinks(window, window->Flags | ImGuiWindowFlags_ChildWindow, node->HostWindow);
+}
+
+static void ImGui::DockNodeRemoveWindow(ImGuiDockNode* node, ImGuiWindow* window, ImGuiID save_dock_id)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(window->DockNode == node);
+    //IM_ASSERT(window->RootWindowDockTree == node->HostWindow);
+    //IM_ASSERT(window->LastFrameActive < g.FrameCount);    // We may call this from Begin()
+    IM_ASSERT(save_dock_id == 0 || save_dock_id == node->ID);
+    IMGUI_DEBUG_LOG_DOCKING("[docking] DockNodeRemoveWindow node 0x%08X window '%s'\n", node->ID, window->Name);
+
+    window->DockNode = NULL;
+    window->DockIsActive = window->DockTabWantClose = false;
+    window->DockId = save_dock_id;
+    window->Flags &= ~ImGuiWindowFlags_ChildWindow;
+    if (window->ParentWindow)
+        window->ParentWindow->DC.ChildWindows.find_erase(window);
+    UpdateWindowParentAndRootLinks(window, window->Flags, NULL); // Update immediately
+
+    if (node->HostWindow && node->HostWindow->ViewportOwned)
+    {
+        // When undocking from a user interaction this will always run in NewFrame() and have not much effect.
+        // But mid-frame, if we clear viewport we need to mark window as hidden as well.
+        window->Viewport = NULL;
+        window->ViewportId = 0;
+        window->ViewportOwned = false;
+        window->Hidden = true;
+    }
+
+    // Remove window
+    bool erased = false;
+    for (int n = 0; n < node->Windows.Size; n++)
+        if (node->Windows[n] == window)
+        {
+            node->Windows.erase(node->Windows.Data + n);
+            erased = true;
+            break;
+        }
+    if (!erased)
+        IM_ASSERT(erased);
+    if (node->VisibleWindow == window)
+        node->VisibleWindow = NULL;
+
+    // Remove tab and possibly tab bar
+    node->WantHiddenTabBarUpdate = true;
+    if (node->TabBar)
+    {
+        TabBarRemoveTab(node->TabBar, window->TabId);
+        const int tab_count_threshold_for_tab_bar = node->IsCentralNode() ? 1 : 2;
+        if (node->Windows.Size < tab_count_threshold_for_tab_bar)
+            DockNodeRemoveTabBar(node);
+    }
+
+    if (node->Windows.Size == 0 && !node->IsCentralNode() && !node->IsDockSpace() && window->DockId != node->ID)
+    {
+        // Automatic dock node delete themselves if they are not holding at least one tab
+        DockContextRemoveNode(&g, node, true);
+        return;
+    }
+
+    if (node->Windows.Size == 1 && !node->IsCentralNode() && node->HostWindow)
+    {
+        ImGuiWindow* remaining_window = node->Windows[0];
+        // Note: we used to transport viewport ownership here.
+        remaining_window->Collapsed = node->HostWindow->Collapsed;
+    }
+
+    // Update visibility immediately is required so the DockNodeUpdateRemoveInactiveChilds() processing can reflect changes up the tree
+    DockNodeUpdateVisibleFlag(node);
+}
+
+static void ImGui::DockNodeMoveChildNodes(ImGuiDockNode* dst_node, ImGuiDockNode* src_node)
+{
+    IM_ASSERT(dst_node->Windows.Size == 0);
+    dst_node->ChildNodes[0] = src_node->ChildNodes[0];
+    dst_node->ChildNodes[1] = src_node->ChildNodes[1];
+    if (dst_node->ChildNodes[0])
+        dst_node->ChildNodes[0]->ParentNode = dst_node;
+    if (dst_node->ChildNodes[1])
+        dst_node->ChildNodes[1]->ParentNode = dst_node;
+    dst_node->SplitAxis = src_node->SplitAxis;
+    dst_node->SizeRef = src_node->SizeRef;
+    src_node->ChildNodes[0] = src_node->ChildNodes[1] = NULL;
+}
+
+static void ImGui::DockNodeMoveWindows(ImGuiDockNode* dst_node, ImGuiDockNode* src_node)
+{
+    // Insert tabs in the same orders as currently ordered (node->Windows isn't ordered)
+    IM_ASSERT(src_node && dst_node && dst_node != src_node);
+    ImGuiTabBar* src_tab_bar = src_node->TabBar;
+    if (src_tab_bar != NULL)
+        IM_ASSERT(src_node->Windows.Size <= src_node->TabBar->Tabs.Size);
+
+    // If the dst_node is empty we can just move the entire tab bar (to preserve selection, scrolling, etc.)
+    bool move_tab_bar = (src_tab_bar != NULL) && (dst_node->TabBar == NULL);
+    if (move_tab_bar)
+    {
+        dst_node->TabBar = src_node->TabBar;
+        src_node->TabBar = NULL;
+    }
+
+    // Tab order is not important here, it is preserved by sorting in DockNodeUpdateTabBar().
+    for (ImGuiWindow* window : src_node->Windows)
+    {
+        window->DockNode = NULL;
+        window->DockIsActive = false;
+        DockNodeAddWindow(dst_node, window, !move_tab_bar);
+    }
+    src_node->Windows.clear();
+
+    if (!move_tab_bar && src_node->TabBar)
+    {
+        if (dst_node->TabBar)
+            dst_node->TabBar->SelectedTabId = src_node->TabBar->SelectedTabId;
+        DockNodeRemoveTabBar(src_node);
+    }
+}
+
+static void ImGui::DockNodeApplyPosSizeToWindows(ImGuiDockNode* node)
+{
+    for (ImGuiWindow* window : node->Windows)
+    {
+        SetWindowPos(window, node->Pos, ImGuiCond_Always); // We don't assign directly to Pos because it can break the calculation of SizeContents on next frame
+        SetWindowSize(window, node->Size, ImGuiCond_Always);
+    }
+}
+
+static void ImGui::DockNodeHideHostWindow(ImGuiDockNode* node)
+{
+    if (node->HostWindow)
+    {
+        if (node->HostWindow->DockNodeAsHost == node)
+            node->HostWindow->DockNodeAsHost = NULL;
+        node->HostWindow = NULL;
+    }
+
+    if (node->Windows.Size == 1)
+    {
+        node->VisibleWindow = node->Windows[0];
+        node->Windows[0]->DockIsActive = false;
+    }
+
+    if (node->TabBar)
+        DockNodeRemoveTabBar(node);
+}
+
+// Search function called once by root node in DockNodeUpdate()
+struct ImGuiDockNodeTreeInfo
+{
+    ImGuiDockNode*      CentralNode;
+    ImGuiDockNode*      FirstNodeWithWindows;
+    int                 CountNodesWithWindows;
+    //ImGuiWindowClass  WindowClassForMerges;
+
+    ImGuiDockNodeTreeInfo() { memset((void*)this, 0, sizeof(*this)); }
+};
+
+static void DockNodeFindInfo(ImGuiDockNode* node, ImGuiDockNodeTreeInfo* info)
+{
+    if (node->Windows.Size > 0)
+    {
+        if (info->FirstNodeWithWindows == NULL)
+            info->FirstNodeWithWindows = node;
+        info->CountNodesWithWindows++;
+    }
+    if (node->IsCentralNode())
+    {
+        IM_ASSERT(info->CentralNode == NULL); // Should be only one
+        IM_ASSERT(node->IsLeafNode() && "If you get this assert: please submit .ini file + repro of actions leading to this.");
+        info->CentralNode = node;
+    }
+    if (info->CountNodesWithWindows > 1 && info->CentralNode != NULL)
+        return;
+    if (node->ChildNodes[0])
+        DockNodeFindInfo(node->ChildNodes[0], info);
+    if (node->ChildNodes[1])
+        DockNodeFindInfo(node->ChildNodes[1], info);
+}
+
+static ImGuiWindow* ImGui::DockNodeFindWindowByID(ImGuiDockNode* node, ImGuiID id)
+{
+    IM_ASSERT(id != 0);
+    for (ImGuiWindow* window : node->Windows)
+        if (window->ID == id)
+            return window;
+    return NULL;
+}
+
+// - Remove inactive windows/nodes.
+// - Update visibility flag.
+static void ImGui::DockNodeUpdateFlagsAndCollapse(ImGuiDockNode* node)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(node->ParentNode == NULL || node->ParentNode->ChildNodes[0] == node || node->ParentNode->ChildNodes[1] == node);
+
+    // Inherit most flags
+    if (node->ParentNode)
+        node->SharedFlags = node->ParentNode->SharedFlags & ImGuiDockNodeFlags_SharedFlagsInheritMask_;
+
+    // Recurse into children
+    // There is the possibility that one of our child becoming empty will delete itself and moving its sibling contents into 'node'.
+    // If 'node->ChildNode[0]' delete itself, then 'node->ChildNode[1]->Windows' will be moved into 'node'
+    // If 'node->ChildNode[1]' delete itself, then 'node->ChildNode[0]->Windows' will be moved into 'node' and the "remove inactive windows" loop will have run twice on those windows (harmless)
+    node->HasCentralNodeChild = false;
+    if (node->ChildNodes[0])
+        DockNodeUpdateFlagsAndCollapse(node->ChildNodes[0]);
+    if (node->ChildNodes[1])
+        DockNodeUpdateFlagsAndCollapse(node->ChildNodes[1]);
+
+    // Remove inactive windows, collapse nodes
+    // Merge node flags overrides stored in windows
+    node->LocalFlagsInWindows = ImGuiDockNodeFlags_None;
+    for (int window_n = 0; window_n < node->Windows.Size; window_n++)
+    {
+        ImGuiWindow* window = node->Windows[window_n];
+        IM_ASSERT(window->DockNode == node);
+
+        bool node_was_active = (node->LastFrameActive + 1 == g.FrameCount);
+        bool remove = false;
+        remove |= node_was_active && (window->WasActive == false); // Can't use 'window->LastFrameActive + 1 < g.FrameCount'. (see #9151)
+        remove |= node_was_active && (node->WantCloseAll || node->WantCloseTabId == window->TabId) && window->HasCloseButton && !(window->Flags & ImGuiWindowFlags_UnsavedDocument);  // Submit all _expected_ closure from last frame
+        remove |= (window->DockTabWantClose);
+        if (remove)
+        {
+            window->DockTabWantClose = false;
+            if (node->Windows.Size == 1 && !node->IsCentralNode())
+            {
+                DockNodeHideHostWindow(node);
+                node->State = ImGuiDockNodeState_HostWindowHiddenBecauseSingleWindow;
+                DockNodeRemoveWindow(node, window, node->ID); // Will delete the node so it'll be invalid on return
+                return;
+            }
+            DockNodeRemoveWindow(node, window, node->ID);
+            window_n--;
+            continue;
+        }
+
+        // FIXME-DOCKING: Missing policies for conflict resolution, hence the "Experimental" tag on this.
+        //node->LocalFlagsInWindow &= ~window->WindowClass.DockNodeFlagsOverrideClear;
+        node->LocalFlagsInWindows |= window->WindowClass.DockNodeFlagsOverrideSet;
+    }
+    node->UpdateMergedFlags();
+
+    // Auto-hide tab bar option
+    ImGuiDockNodeFlags node_flags = node->MergedFlags;
+    if (node->WantHiddenTabBarUpdate && node->Windows.Size == 1 && (node_flags & ImGuiDockNodeFlags_AutoHideTabBar) && !node->IsHiddenTabBar())
+        node->WantHiddenTabBarToggle = true;
+    node->WantHiddenTabBarUpdate = false;
+
+    // Cancel toggling if we know our tab bar is enforced to be hidden at all times
+    if (node->WantHiddenTabBarToggle && node->VisibleWindow && (node->VisibleWindow->WindowClass.DockNodeFlagsOverrideSet & ImGuiDockNodeFlags_HiddenTabBar))
+        node->WantHiddenTabBarToggle = false;
+
+    // Apply toggles at a single point of the frame (here!)
+    if (node->Windows.Size > 1)
+        node->SetLocalFlags(node->LocalFlags & ~ImGuiDockNodeFlags_HiddenTabBar);
+    else if (node->WantHiddenTabBarToggle)
+        node->SetLocalFlags(node->LocalFlags ^ ImGuiDockNodeFlags_HiddenTabBar);
+    node->WantHiddenTabBarToggle = false;
+
+    DockNodeUpdateVisibleFlag(node);
+}
+
+// This is rarely called as DockNodeUpdateForRootNode() generally does it most frames.
+static void ImGui::DockNodeUpdateHasCentralNodeChild(ImGuiDockNode* node)
+{
+    node->HasCentralNodeChild = false;
+    if (node->ChildNodes[0])
+        DockNodeUpdateHasCentralNodeChild(node->ChildNodes[0]);
+    if (node->ChildNodes[1])
+        DockNodeUpdateHasCentralNodeChild(node->ChildNodes[1]);
+    if (node->IsRootNode())
+    {
+        ImGuiDockNode* mark_node = node->CentralNode;
+        while (mark_node)
+        {
+            mark_node->HasCentralNodeChild = true;
+            mark_node = mark_node->ParentNode;
+        }
+    }
+}
+
+static void ImGui::DockNodeUpdateVisibleFlag(ImGuiDockNode* node)
+{
+    // Update visibility flag
+    bool is_visible = (node->ParentNode == NULL) ? node->IsDockSpace() : node->IsCentralNode();
+    is_visible |= (node->Windows.Size > 0);
+    is_visible |= (node->ChildNodes[0] && node->ChildNodes[0]->IsVisible);
+    is_visible |= (node->ChildNodes[1] && node->ChildNodes[1]->IsVisible);
+    node->IsVisible = is_visible;
+}
+
+static void ImGui::DockNodeStartMouseMovingWindow(ImGuiDockNode* node, ImGuiWindow* window)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(node->WantMouseMove == true);
+    StartMouseMovingWindow(window);
+    g.ActiveIdClickOffset = g.IO.MouseClickedPos[0] - node->Pos;
+    g.MovingWindow = window; // If we are docked into a non moveable root window, StartMouseMovingWindow() won't set g.MovingWindow. Override that decision.
+    node->WantMouseMove = false;
+}
+
+// Update CentralNode, OnlyNodeWithWindows, LastFocusedNodeID. Copy window class.
+static void ImGui::DockNodeUpdateForRootNode(ImGuiDockNode* node)
+{
+    DockNodeUpdateFlagsAndCollapse(node);
+
+    // - Setup central node pointers
+    // - Find if there's only a single visible window in the hierarchy (in which case we need to display a regular title bar -> FIXME-DOCK: that last part is not done yet!)
+    // Cannot merge this with DockNodeUpdateFlagsAndCollapse() because FirstNodeWithWindows is found after window removal and child collapsing
+    ImGuiDockNodeTreeInfo info;
+    DockNodeFindInfo(node, &info);
+    node->CentralNode = info.CentralNode;
+    node->OnlyNodeWithWindows = (info.CountNodesWithWindows == 1) ? info.FirstNodeWithWindows : NULL;
+    node->CountNodeWithWindows = info.CountNodesWithWindows;
+    if (node->LastFocusedNodeId == 0 && info.FirstNodeWithWindows != NULL)
+        node->LastFocusedNodeId = info.FirstNodeWithWindows->ID;
+
+    // Copy the window class from of our first window so it can be used for proper dock filtering.
+    // When node has mixed windows, prioritize the class with the most constraint (DockingAllowUnclassed = false) as the reference to copy.
+    // FIXME-DOCK: We don't recurse properly, this code could be reworked to work from DockNodeUpdateScanRec.
+    if (ImGuiDockNode* first_node_with_windows = info.FirstNodeWithWindows)
+    {
+        node->WindowClass = first_node_with_windows->Windows[0]->WindowClass;
+        for (int n = 1; n < first_node_with_windows->Windows.Size; n++)
+            if (first_node_with_windows->Windows[n]->WindowClass.DockingAllowUnclassed == false)
+            {
+                node->WindowClass = first_node_with_windows->Windows[n]->WindowClass;
+                break;
+            }
+    }
+
+    ImGuiDockNode* mark_node = node->CentralNode;
+    while (mark_node)
+    {
+        mark_node->HasCentralNodeChild = true;
+        mark_node = mark_node->ParentNode;
+    }
+}
+
+static void DockNodeSetupHostWindow(ImGuiDockNode* node, ImGuiWindow* host_window)
+{
+    // Remove ourselves from any previous different host window
+    // This can happen if a user mistakenly does (see #4295 for details):
+    //  - N+0: DockBuilderAddNode(id, 0)    // missing ImGuiDockNodeFlags_DockSpace
+    //  - N+1: NewFrame()                   // will create floating host window for that node
+    //  - N+1: DockSpace(id)                // requalify node as dockspace, moving host window
+    if (node->HostWindow && node->HostWindow != host_window && node->HostWindow->DockNodeAsHost == node)
+        node->HostWindow->DockNodeAsHost = NULL;
+
+    host_window->DockNodeAsHost = node;
+    node->HostWindow = host_window;
+}
+
+static void ImGui::DockNodeUpdate(ImGuiDockNode* node)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(node->LastFrameActive != g.FrameCount);
+    node->LastFrameAlive = g.FrameCount;
+    node->IsBgDrawnThisFrame = false;
+
+    node->CentralNode = node->OnlyNodeWithWindows = NULL;
+    if (node->IsRootNode())
+        DockNodeUpdateForRootNode(node);
+
+    // Remove tab bar if not needed
+    if (node->TabBar && node->IsNoTabBar())
+        DockNodeRemoveTabBar(node);
+
+    // Early out for hidden root dock nodes (when all DockId references are in inactive windows, or there is only 1 floating window holding on the DockId)
+    bool want_to_hide_host_window = false;
+    if (node->IsFloatingNode())
+    {
+        if (node->Windows.Size <= 1 && node->IsLeafNode())
+            if (!g.IO.ConfigDockingAlwaysTabBar && (node->Windows.Size == 0 || !node->Windows[0]->WindowClass.DockingAlwaysTabBar))
+                want_to_hide_host_window = true;
+        if (node->CountNodeWithWindows == 0)
+            want_to_hide_host_window = true;
+    }
+    if (want_to_hide_host_window)
+    {
+        if (node->Windows.Size == 1)
+        {
+            // Floating window pos/size is authoritative
+            ImGuiWindow* single_window = node->Windows[0];
+            node->Pos = single_window->Pos;
+            node->Size = single_window->SizeFull;
+            node->AuthorityForPos = node->AuthorityForSize = node->AuthorityForViewport = ImGuiDataAuthority_Window;
+
+            // Transfer focus immediately so when we revert to a regular window it is immediately selected
+            if (node->HostWindow && g.NavWindow == node->HostWindow)
+                FocusWindow(single_window);
+            if (node->HostWindow)
+            {
+                IMGUI_DEBUG_LOG_VIEWPORT("[viewport] Node %08X transfer Viewport %08X->%08X to Window '%s'\n", node->ID, node->HostWindow->Viewport->ID, single_window->ID, single_window->Name);
+                single_window->Viewport = node->HostWindow->Viewport;
+                single_window->ViewportId = node->HostWindow->ViewportId;
+                if (node->HostWindow->ViewportOwned)
+                {
+                    single_window->Viewport->ID = single_window->ID;
+                    single_window->Viewport->Window = single_window;
+                    single_window->ViewportOwned = true;
+                }
+            }
+            node->RefViewportId = single_window->ViewportId;
+        }
+
+        DockNodeHideHostWindow(node);
+        node->State = ImGuiDockNodeState_HostWindowHiddenBecauseSingleWindow;
+        node->WantCloseAll = false;
+        node->WantCloseTabId = 0;
+        node->HasCloseButton = node->HasWindowMenuButton = false;
+        node->LastFrameActive = g.FrameCount;
+
+        if (node->WantMouseMove && node->Windows.Size == 1)
+            DockNodeStartMouseMovingWindow(node, node->Windows[0]);
+        return;
+    }
+
+    // In some circumstance we will defer creating the host window (so everything will be kept hidden),
+    // while the expected visible window is resizing itself.
+    // This is important for first-time (no ini settings restored) single window when io.ConfigDockingAlwaysTabBar is enabled,
+    // otherwise the node ends up using the minimum window size. Effectively those windows will take an extra frame to show up:
+    //   N+0: Begin(): window created (with no known size), node is created
+    //   N+1: DockNodeUpdate(): node skip creating host window / Begin(): window size applied, not visible
+    //   N+2: DockNodeUpdate(): node can create host window / Begin(): window becomes visible
+    // We could remove this frame if we could reliably calculate the expected window size during node update, before the Begin() code.
+    // It would require a generalization of CalcWindowExpectedSize(), probably extracting code away from Begin().
+    // In reality it isn't very important as user quickly ends up with size data in .ini file.
+    if (node->IsVisible && node->HostWindow == NULL && node->IsFloatingNode() && node->IsLeafNode())
+    {
+        IM_ASSERT(node->Windows.Size > 0);
+        ImGuiWindow* ref_window = NULL;
+        if (node->SelectedTabId != 0) // Note that we prune single-window-node settings on .ini loading, so this is generally 0 for them!
+            ref_window = DockNodeFindWindowByID(node, node->SelectedTabId);
+        if (ref_window == NULL)
+            ref_window = node->Windows[0];
+        if (ref_window->AutoFitFramesX > 0 || ref_window->AutoFitFramesY > 0)
+        {
+            node->State = ImGuiDockNodeState_HostWindowHiddenBecauseWindowsAreResizing;
+            return;
+        }
+    }
+
+    const ImGuiDockNodeFlags node_flags = node->MergedFlags;
+
+    // Decide if the node will have a close button and a window menu button
+    node->HasWindowMenuButton = (node->Windows.Size > 0) && (node_flags & ImGuiDockNodeFlags_NoWindowMenuButton) == 0;
+    node->HasCloseButton = false;
+    for (ImGuiWindow* window : node->Windows)
+    {
+        // FIXME-DOCK: Setting DockIsActive here means that for single active window in a leaf node, DockIsActive will be cleared until the next Begin() call.
+        node->HasCloseButton |= window->HasCloseButton;
+        window->DockIsActive = (node->Windows.Size > 1);
+    }
+    if ((node_flags & ImGuiDockNodeFlags_NoCloseButton) || !g.Style.DockingNodeHasCloseButton)
+        node->HasCloseButton = false;
+
+    // Bind or create host window
+    ImGuiWindow* host_window = NULL;
+    bool beginned_into_host_window = false;
+    if (node->IsDockSpace())
+    {
+        // [Explicit root dockspace node]
+        IM_ASSERT(node->HostWindow);
+        host_window = node->HostWindow;
+    }
+    else
+    {
+        // [Automatic root or child nodes]
+        if (node->IsRootNode() && node->IsVisible)
+        {
+            ImGuiWindow* ref_window = (node->Windows.Size > 0) ? node->Windows[0] : NULL;
+
+            // Sync Pos
+            if (node->AuthorityForPos == ImGuiDataAuthority_Window && ref_window)
+                SetNextWindowPos(ref_window->Pos);
+            else if (node->AuthorityForPos == ImGuiDataAuthority_DockNode)
+                SetNextWindowPos(node->Pos);
+
+            // Sync Size
+            if (node->AuthorityForSize == ImGuiDataAuthority_Window && ref_window)
+                SetNextWindowSize(ref_window->SizeFull);
+            else if (node->AuthorityForSize == ImGuiDataAuthority_DockNode)
+                SetNextWindowSize(node->Size);
+
+            // Sync Collapsed
+            if (node->AuthorityForSize == ImGuiDataAuthority_Window && ref_window)
+                SetNextWindowCollapsed(ref_window->Collapsed);
+
+            // Sync Viewport
+            if (node->AuthorityForViewport == ImGuiDataAuthority_Window && ref_window)
+                SetNextWindowViewport(ref_window->ViewportId);
+            else if (node->AuthorityForViewport == ImGuiDataAuthority_Window && node->RefViewportId != 0)
+                SetNextWindowViewport(node->RefViewportId);
+
+            SetNextWindowClass(&node->WindowClass);
+
+            // Begin into the host window
+            char window_label[20];
+            DockNodeGetHostWindowTitle(node, window_label, IM_COUNTOF(window_label));
+            ImGuiWindowFlags window_flags = ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoScrollWithMouse | ImGuiWindowFlags_DockNodeHost;
+            window_flags |= ImGuiWindowFlags_NoFocusOnAppearing;
+            window_flags |= ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoNavFocus | ImGuiWindowFlags_NoCollapse;
+            window_flags |= ImGuiWindowFlags_NoTitleBar;
+
+            SetNextWindowBgAlpha(0.0f); // Don't set ImGuiWindowFlags_NoBackground because it disables borders
+            PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(0, 0));
+            Begin(window_label, NULL, window_flags);
+            PopStyleVar();
+            beginned_into_host_window = true;
+
+            host_window = g.CurrentWindow;
+            DockNodeSetupHostWindow(node, host_window);
+            host_window->DC.CursorPos = host_window->Pos;
+            node->Pos = host_window->Pos;
+            node->Size = host_window->Size;
+
+            // We set ImGuiWindowFlags_NoFocusOnAppearing because we don't want the host window to take full focus (e.g. steal NavWindow)
+            // But we still it bring it to the front of display. There's no way to choose this precise behavior via window flags.
+            // One simple case to ponder if: window A has a toggle to create windows B/C/D. Dock B/C/D together, clear the toggle and enable it again.
+            // When reappearing B/C/D will request focus and be moved to the top of the display pile, but they are not linked to the dock host window
+            // during the frame they appear. The dock host window would keep its old display order, and the sorting in EndFrame would move B/C/D back
+            // after the dock host window, losing their top-most status.
+            if (node->HostWindow->Appearing)
+                BringWindowToDisplayFront(node->HostWindow);
+
+            node->AuthorityForPos = node->AuthorityForSize = node->AuthorityForViewport = ImGuiDataAuthority_Auto;
+        }
+        else if (node->ParentNode)
+        {
+            node->HostWindow = host_window = node->ParentNode->HostWindow;
+            node->AuthorityForPos = node->AuthorityForSize = node->AuthorityForViewport = ImGuiDataAuthority_Auto;
+        }
+        if (node->WantMouseMove && node->HostWindow)
+            DockNodeStartMouseMovingWindow(node, node->HostWindow);
+    }
+    node->RefViewportId = 0; // Clear when we have a host window
+
+    // Update focused node (the one whose title bar is highlight) within a node tree
+    if (node->IsSplitNode())
+        IM_ASSERT(node->TabBar == NULL);
+    if (node->IsRootNode())
+        if (ImGuiWindow* p_window = g.NavWindow ? g.NavWindow->RootWindow : NULL)
+            while (p_window != NULL && p_window->DockNode != NULL)
+            {
+                ImGuiDockNode* p_node = DockNodeGetRootNode(p_window->DockNode);
+                if (p_node == node)
+                {
+                    node->LastFocusedNodeId = p_window->DockNode->ID; // Note: not using root node ID!
+                    break;
+                }
+                p_window = p_node->HostWindow ? p_node->HostWindow->RootWindow : NULL;
+            }
+
+    // Register a hit-test hole in the window unless we are currently dragging a window that is compatible with our dockspace
+    ImGuiDockNode* central_node = node->CentralNode;
+    const bool central_node_hole = node->IsRootNode() && host_window && (node_flags & ImGuiDockNodeFlags_PassthruCentralNode) != 0 && central_node != NULL && central_node->IsEmpty();
+    bool central_node_hole_register_hit_test_hole = central_node_hole;
+    if (central_node_hole)
+        if (const ImGuiPayload* payload = ImGui::GetDragDropPayload())
+            if (payload->IsDataType(IMGUI_PAYLOAD_TYPE_WINDOW) && DockNodeIsDropAllowed(host_window, *(ImGuiWindow**)payload->Data))
+                central_node_hole_register_hit_test_hole = false;
+    if (central_node_hole_register_hit_test_hole)
+    {
+        // We add a little padding to match the "resize from edges" behavior and allow grabbing the splitter easily.
+        // (But we only add it if there's something else on the other side of the hole, otherwise for e.g. fullscreen
+        // covering passthru node we'd have a gap on the edge not covered by the hole)
+        IM_ASSERT(node->IsDockSpace()); // We cannot pass this flag without the DockSpace() api. Testing this because we also setup the hole in host_window->ParentNode
+        ImGuiDockNode* root_node = DockNodeGetRootNode(central_node);
+        ImRect root_rect(root_node->Pos, root_node->Pos + root_node->Size);
+        ImRect hole_rect(central_node->Pos, central_node->Pos + central_node->Size);
+        if (hole_rect.Min.x > root_rect.Min.x) { hole_rect.Min.x += g.WindowsBorderHoverPadding; }
+        if (hole_rect.Max.x < root_rect.Max.x) { hole_rect.Max.x -= g.WindowsBorderHoverPadding; }
+        if (hole_rect.Min.y > root_rect.Min.y) { hole_rect.Min.y += g.WindowsBorderHoverPadding; }
+        if (hole_rect.Max.y < root_rect.Max.y) { hole_rect.Max.y -= g.WindowsBorderHoverPadding; }
+        //GetForegroundDrawList()->AddRect(hole_rect.Min, hole_rect.Max, IM_COL32(255, 0, 0, 255));
+        if (central_node_hole && !hole_rect.IsInverted())
+        {
+            SetWindowHitTestHole(host_window, hole_rect.Min, hole_rect.Max - hole_rect.Min);
+            if (host_window->ParentWindow)
+                SetWindowHitTestHole(host_window->ParentWindow, hole_rect.Min, hole_rect.Max - hole_rect.Min);
+        }
+    }
+
+    // Update position/size, process and draw resizing splitters
+    if (node->IsRootNode() && host_window)
+    {
+        DockNodeTreeUpdatePosSize(node, host_window->Pos, host_window->Size);
+        PushStyleColor(ImGuiCol_Separator, g.Style.Colors[ImGuiCol_Border]);
+        PushStyleColor(ImGuiCol_SeparatorActive, g.Style.Colors[ImGuiCol_ResizeGripActive]);
+        PushStyleColor(ImGuiCol_SeparatorHovered, g.Style.Colors[ImGuiCol_ResizeGripHovered]);
+        DockNodeTreeUpdateSplitter(node);
+        PopStyleColor(3);
+    }
+
+    // Draw empty node background (currently can only be the Central Node)
+    if (host_window && node->IsEmpty() && node->IsVisible)
+    {
+        host_window->DrawList->ChannelsSetCurrent(DOCKING_HOST_DRAW_CHANNEL_BG);
+        node->LastBgColor = (node_flags & ImGuiDockNodeFlags_PassthruCentralNode) ? 0 : GetColorU32(ImGuiCol_DockingEmptyBg);
+        if (node->LastBgColor != 0)
+            host_window->DrawList->AddRectFilled(node->Pos, node->Pos + node->Size, node->LastBgColor);
+        node->IsBgDrawnThisFrame = true;
+    }
+
+    // Draw whole dockspace background if ImGuiDockNodeFlags_PassthruCentralNode if set.
+    // We need to draw a background at the root level if requested by ImGuiDockNodeFlags_PassthruCentralNode, but we will only know the correct pos/size
+    // _after_ processing the resizing splitters. So we are using the DrawList channel splitting facility to submit drawing primitives out of order!
+    const bool render_dockspace_bg = node->IsRootNode() && host_window && (node_flags & ImGuiDockNodeFlags_PassthruCentralNode) != 0;
+    if (render_dockspace_bg && node->IsVisible)
+    {
+        host_window->DrawList->ChannelsSetCurrent(DOCKING_HOST_DRAW_CHANNEL_BG);
+        if (central_node_hole)
+            RenderRectFilledWithHole(host_window->DrawList, node->Rect(), central_node->Rect(), GetColorU32(ImGuiCol_WindowBg), 0.0f);
+        else
+            host_window->DrawList->AddRectFilled(node->Pos, node->Pos + node->Size, GetColorU32(ImGuiCol_WindowBg), 0.0f);
+    }
+
+    // Draw and populate Tab Bar
+    if (host_window)
+        host_window->DrawList->ChannelsSetCurrent(DOCKING_HOST_DRAW_CHANNEL_FG);
+    if (host_window && node->Windows.Size > 0)
+    {
+        DockNodeUpdateTabBar(node, host_window);
+    }
+    else
+    {
+        node->WantCloseAll = false;
+        node->WantCloseTabId = 0;
+        node->IsFocused = false;
+    }
+    if (node->TabBar && node->TabBar->SelectedTabId)
+        node->SelectedTabId = node->TabBar->SelectedTabId;
+    else if (node->Windows.Size > 0)
+        node->SelectedTabId = node->Windows[0]->TabId;
+
+    // Draw payload drop target
+    if (host_window && node->IsVisible)
+        if (node->IsRootNode() && (g.MovingWindow == NULL || g.MovingWindow->RootWindowDockTree != host_window))
+            BeginDockableDragDropTarget(host_window);
+
+    // We update this after DockNodeUpdateTabBar()
+    node->LastFrameActive = g.FrameCount;
+
+    // Recurse into children
+    // FIXME-DOCK FIXME-OPT: Should not need to recurse into children
+    if (host_window)
+    {
+        if (node->ChildNodes[0])
+            DockNodeUpdate(node->ChildNodes[0]);
+        if (node->ChildNodes[1])
+            DockNodeUpdate(node->ChildNodes[1]);
+
+        // Render outer borders last (after the tab bar)
+        if (node->IsRootNode())
+            RenderWindowOuterBorders(host_window);
+    }
+
+    // End host window
+    if (beginned_into_host_window) //-V1020
+        End();
+}
+
+// Compare TabItem nodes given the last known DockOrder (will persist in .ini file as hint), used to sort tabs when multiple tabs are added on the same frame.
+static int IMGUI_CDECL TabItemComparerByDockOrder(const void* lhs, const void* rhs)
+{
+    ImGuiWindow* a = ((const ImGuiTabItem*)lhs)->Window;
+    ImGuiWindow* b = ((const ImGuiTabItem*)rhs)->Window;
+    if (int d = ((a->DockOrder == -1) ? INT_MAX : a->DockOrder) - ((b->DockOrder == -1) ? INT_MAX : b->DockOrder))
+        return d;
+    return (a->BeginOrderWithinContext - b->BeginOrderWithinContext);
+}
+
+// Default handler for g.DockNodeWindowMenuHandler(): display the list of windows for a given dock-node.
+// This is exceptionally stored in a function pointer to also user applications to tweak this menu (undocumented)
+// Custom overrides may want to decorate, group, sort entries.
+// Please note those are internal structures: if you copy this expect occasional breakage.
+// (if you don't need to modify the "Tabs.Size == 1" behavior/path it is recommend you call this function in your handler)
+void ImGui::DockNodeWindowMenuHandler_Default(ImGuiContext* ctx, ImGuiDockNode* node, ImGuiTabBar* tab_bar)
+{
+    IM_UNUSED(ctx);
+    if (tab_bar->Tabs.Size == 1)
+    {
+        // "Hide tab bar" option. Being one of our rare user-facing string we pull it from a table.
+        if (MenuItem(LocalizeGetMsg(ImGuiLocKey_DockingHideTabBar), NULL, node->IsHiddenTabBar()))
+            node->WantHiddenTabBarToggle = true;
+    }
+    else
+    {
+        // Display a selectable list of windows in this docking node
+        for (int tab_n = 0; tab_n < tab_bar->Tabs.Size; tab_n++)
+        {
+            ImGuiTabItem* tab = &tab_bar->Tabs[tab_n];
+            if (tab->Flags & ImGuiTabItemFlags_Button)
+                continue;
+            if (Selectable(TabBarGetTabName(tab_bar, tab), tab->ID == tab_bar->SelectedTabId))
+                TabBarQueueFocus(tab_bar, tab);
+            SameLine();
+            Text("   ");
+        }
+    }
+}
+
+static void ImGui::DockNodeWindowMenuUpdate(ImGuiDockNode* node, ImGuiTabBar* tab_bar)
+{
+    // Try to position the menu so it is more likely to stays within the same viewport
+    ImGuiContext& g = *GImGui;
+    if (g.Style.WindowMenuButtonPosition == ImGuiDir_Left)
+        SetNextWindowPos(ImVec2(node->Pos.x, node->Pos.y + GetFrameHeight()), ImGuiCond_Always, ImVec2(0.0f, 0.0f));
+    else
+        SetNextWindowPos(ImVec2(node->Pos.x + node->Size.x, node->Pos.y + GetFrameHeight()), ImGuiCond_Always, ImVec2(1.0f, 0.0f));
+    if (BeginPopup("#WindowMenu"))
+    {
+        node->IsFocused = true;
+        g.DockNodeWindowMenuHandler(&g, node, tab_bar);
+        EndPopup();
+    }
+}
+
+// User helper to append/amend into a dock node tab bar. Most commonly used to add e.g. a "+" button.
+bool ImGui::DockNodeBeginAmendTabBar(ImGuiDockNode* node)
+{
+    if (node->TabBar == NULL || node->HostWindow == NULL)
+        return false;
+    if (node->MergedFlags & ImGuiDockNodeFlags_KeepAliveOnly)
+        return false;
+    if (node->TabBar->ID == 0)
+        return false;
+    Begin(node->HostWindow->Name);
+    PushOverrideID(node->ID);
+    bool ret = BeginTabBarEx(node->TabBar, node->TabBar->BarRect, node->TabBar->Flags);
+    IM_UNUSED(ret);
+    IM_ASSERT(ret);
+    return true;
+}
+
+void ImGui::DockNodeEndAmendTabBar()
+{
+    EndTabBar();
+    PopID();
+    End();
+}
+
+static bool IsDockNodeTitleBarHighlighted(ImGuiDockNode* node, ImGuiDockNode* root_node)
+{
+    // CTRL+Tab highlight (only highlighting leaf node, not whole hierarchy)
+    ImGuiContext& g = *GImGui;
+    if (g.NavWindowingTarget)
+        return (g.NavWindowingTarget->DockNode == node);
+
+    // FIXME-DOCKING: May want alternative to treat central node void differently? e.g. if (g.NavWindow == host_window)
+    if (g.NavWindow && root_node->LastFocusedNodeId == node->ID)
+    {
+        // FIXME: This could all be backed in RootWindowForTitleBarHighlight? Probably need to reorganize for both dock nodes + other RootWindowForTitleBarHighlight users (not-node)
+        ImGuiWindow* parent_window = g.NavWindow->RootWindow;
+        while (parent_window->Flags & ImGuiWindowFlags_ChildMenu)
+            parent_window = parent_window->ParentWindow->RootWindow;
+        ImGuiDockNode* start_parent_node = parent_window->DockNodeAsHost ? parent_window->DockNodeAsHost : parent_window->DockNode;
+        for (ImGuiDockNode* parent_node = start_parent_node; parent_node != NULL; parent_node = parent_node->HostWindow ? parent_node->HostWindow->RootWindow->DockNode : NULL)
+            if ((parent_node = ImGui::DockNodeGetRootNode(parent_node)) == root_node)
+                return true;
+    }
+    return false;
+}
+
+// Submit the tab bar corresponding to a dock node and various housekeeping details.
+static void ImGui::DockNodeUpdateTabBar(ImGuiDockNode* node, ImGuiWindow* host_window)
+{
+    ImGuiContext& g = *GImGui;
+    ImGuiStyle& style = g.Style;
+
+    const bool node_was_active = (node->LastFrameActive + 1 == g.FrameCount);
+    node->WantCloseAll = false;
+    node->WantCloseTabId = 0;
+
+    // Decide if we should use a focused title bar color
+    bool is_focused = false;
+    ImGuiDockNode* root_node = DockNodeGetRootNode(node);
+    if (IsDockNodeTitleBarHighlighted(node, root_node))
+        is_focused = true;
+
+    // Hidden tab bar will show a triangle on the upper-left (in Begin)
+    if (node->IsHiddenTabBar() || node->IsNoTabBar())
+    {
+        node->VisibleWindow = (node->Windows.Size > 0) ? node->Windows[0] : NULL;
+        node->IsFocused = is_focused;
+        if (is_focused)
+            node->LastFrameFocused = g.FrameCount;
+        if (node->VisibleWindow)
+        {
+            // Notify root of visible window (used to display title in OS task bar)
+            if (is_focused || root_node->VisibleWindow == NULL)
+                root_node->VisibleWindow = node->VisibleWindow;
+            if (node->TabBar)
+                node->TabBar->VisibleTabId = node->VisibleWindow->TabId;
+        }
+        return;
+    }
+
+    // Move ourselves to the Menu layer (so we can be accessed by tapping Alt) + undo SkipItems flag in order to draw over the title bar even if the window is collapsed
+    bool backup_skip_item = host_window->SkipItems;
+    if (!node->IsDockSpace())
+    {
+        host_window->SkipItems = false;
+        host_window->DC.NavLayerCurrent = ImGuiNavLayer_Menu;
+    }
+
+    // Use PushOverrideID() instead of PushID() to use the node id _without_ the host window ID.
+    // This is to facilitate computing those ID from the outside, and will affect more or less only the ID of the collapse button, popup and tabs,
+    // as docked windows themselves will override the stack with their own root ID.
+    PushOverrideID(node->ID);
+    ImGuiTabBar* tab_bar = node->TabBar;
+    bool tab_bar_is_recreated = (tab_bar == NULL); // Tab bar are automatically destroyed when a node gets hidden
+    if (tab_bar == NULL)
+    {
+        DockNodeAddTabBar(node);
+        tab_bar = node->TabBar;
+    }
+
+    ImGuiID focus_tab_id = 0;
+    node->IsFocused = is_focused;
+
+    const ImGuiDockNodeFlags node_flags = node->MergedFlags;
+    const bool has_window_menu_button = (node_flags & ImGuiDockNodeFlags_NoWindowMenuButton) == 0 && (style.WindowMenuButtonPosition != ImGuiDir_None);
+
+    // In a dock node, the Collapse Button turns into the Window Menu button.
+    // FIXME-DOCK FIXME-OPT: Could we recycle popups id across multiple dock nodes?
+    if (has_window_menu_button && IsPopupOpen("#WindowMenu"))
+    {
+        ImGuiID next_selected_tab_id = tab_bar->NextSelectedTabId;
+        DockNodeWindowMenuUpdate(node, tab_bar);
+        if (tab_bar->NextSelectedTabId != 0 && tab_bar->NextSelectedTabId != next_selected_tab_id)
+            focus_tab_id = tab_bar->NextSelectedTabId;
+        is_focused |= node->IsFocused;
+    }
+
+    // Layout
+    ImRect title_bar_rect, tab_bar_rect;
+    ImVec2 window_menu_button_pos;
+    ImVec2 close_button_pos;
+    DockNodeCalcTabBarLayout(node, &title_bar_rect, &tab_bar_rect, &window_menu_button_pos, &close_button_pos);
+
+    // Submit new tabs, they will be added as Unsorted and sorted below based on relative DockOrder value.
+    const int tabs_count_old = tab_bar->Tabs.Size;
+    for (int window_n = 0; window_n < node->Windows.Size; window_n++)
+    {
+        ImGuiWindow* window = node->Windows[window_n];
+        if (TabBarFindTabByID(tab_bar, window->TabId) == NULL)
+            TabBarAddTab(tab_bar, ImGuiTabItemFlags_Unsorted, window);
+    }
+
+    // Title bar
+    if (is_focused)
+        node->LastFrameFocused = g.FrameCount;
+    ImU32 title_bar_col = GetColorU32(host_window->Collapsed ? ImGuiCol_TitleBgCollapsed : is_focused ? ImGuiCol_TitleBgActive : ImGuiCol_TitleBg);
+    ImDrawFlags rounding_flags = CalcRoundingFlagsForRectInRect(title_bar_rect, host_window->Rect(), g.Style.DockingSeparatorSize);
+    host_window->DrawList->AddRectFilled(title_bar_rect.Min, title_bar_rect.Max, title_bar_col, host_window->WindowRounding, rounding_flags);
+
+    // Docking/Collapse button
+    if (has_window_menu_button)
+    {
+        if (CollapseButton(host_window->GetID("#COLLAPSE"), window_menu_button_pos, node)) // == DockNodeGetWindowMenuButtonId(node)
+            OpenPopup("#WindowMenu");
+        if (IsItemActive())
+            focus_tab_id = tab_bar->SelectedTabId;
+        if (IsItemHovered(ImGuiHoveredFlags_ForTooltip | ImGuiHoveredFlags_DelayNormal) && g.HoveredIdTimer > 0.5f)
+            SetTooltip("%s", LocalizeGetMsg(ImGuiLocKey_DockingDragToUndockOrMoveNode));
+    }
+
+    // If multiple tabs are appearing on the same frame, sort them based on their persistent DockOrder value
+    int tabs_unsorted_start = tab_bar->Tabs.Size;
+    for (int tab_n = tab_bar->Tabs.Size - 1; tab_n >= 0 && (tab_bar->Tabs[tab_n].Flags & ImGuiTabItemFlags_Unsorted); tab_n--)
+    {
+        // FIXME-DOCK: Consider only clearing the flag after the tab has been alive for a few consecutive frames, allowing late comers to not break sorting?
+        tab_bar->Tabs[tab_n].Flags &= ~ImGuiTabItemFlags_Unsorted;
+        tabs_unsorted_start = tab_n;
+    }
+    if (tab_bar->Tabs.Size > tabs_unsorted_start)
+    {
+        IMGUI_DEBUG_LOG_DOCKING("[docking] In node 0x%08X: %d new appearing tabs:%s\n", node->ID, tab_bar->Tabs.Size - tabs_unsorted_start, (tab_bar->Tabs.Size > tabs_unsorted_start + 1) ? " (will sort)" : "");
+        for (int tab_n = tabs_unsorted_start; tab_n < tab_bar->Tabs.Size; tab_n++)
+        {
+            ImGuiTabItem* tab = &tab_bar->Tabs[tab_n];
+            IM_UNUSED(tab);
+            IMGUI_DEBUG_LOG_DOCKING("[docking] - Tab 0x%08X '%s' Order %d\n", tab->ID, TabBarGetTabName(tab_bar, tab), tab->Window ? tab->Window->DockOrder : -1);
+        }
+        IMGUI_DEBUG_LOG_DOCKING("[docking] SelectedTabId = 0x%08X, NavWindow->TabId = 0x%08X\n", node->SelectedTabId, g.NavWindow ? g.NavWindow->TabId : -1);
+        if (tab_bar->Tabs.Size > tabs_unsorted_start + 1)
+            ImQsort(tab_bar->Tabs.Data + tabs_unsorted_start, tab_bar->Tabs.Size - tabs_unsorted_start, sizeof(ImGuiTabItem), TabItemComparerByDockOrder);
+    }
+
+    // Apply NavWindow focus back to the tab bar
+    if (g.NavWindow && g.NavWindow->RootWindow->DockNode == node)
+        tab_bar->SelectedTabId = g.NavWindow->RootWindow->TabId;
+
+    // Selected newly added tabs, or persistent tab ID if the tab bar was just recreated
+    if (tab_bar_is_recreated && TabBarFindTabByID(tab_bar, node->SelectedTabId) != NULL)
+        tab_bar->SelectedTabId = tab_bar->NextSelectedTabId = node->SelectedTabId;
+    else if (tab_bar->Tabs.Size > tabs_count_old)
+        tab_bar->SelectedTabId = tab_bar->NextSelectedTabId = tab_bar->Tabs.back().Window->TabId;
+
+    // Begin tab bar
+    ImGuiTabBarFlags tab_bar_flags = ImGuiTabBarFlags_Reorderable | ImGuiTabBarFlags_AutoSelectNewTabs; // | ImGuiTabBarFlags_NoTabListScrollingButtons);
+    tab_bar_flags |= ImGuiTabBarFlags_SaveSettings | ImGuiTabBarFlags_DockNode;
+    tab_bar_flags |= ImGuiTabBarFlags_FittingPolicyMixed; // Enforce default policy. Since 1.92.2 this is now reasonable. May expose later if needed. (#8800, #3421)
+    tab_bar_flags |= ImGuiTabBarFlags_DrawSelectedOverline;
+    if (!host_window->Collapsed && is_focused)
+        tab_bar_flags |= ImGuiTabBarFlags_IsFocused;
+    tab_bar->ID = node->ID;// GetID("#TabBar");
+    tab_bar->SeparatorMinX = node->Pos.x + host_window->WindowBorderSize; // Separator cover the whole node width
+    tab_bar->SeparatorMaxX = node->Pos.x + node->Size.x - host_window->WindowBorderSize;
+    BeginTabBarEx(tab_bar, tab_bar_rect, tab_bar_flags);
+    //host_window->DrawList->AddRect(tab_bar_rect.Min, tab_bar_rect.Max, IM_COL32(255,0,255,255));
+
+    // Backup style colors
+    ImVec4 backup_style_cols[ImGuiWindowDockStyleCol_COUNT];
+    for (int color_n = 0; color_n < ImGuiWindowDockStyleCol_COUNT; color_n++)
+        backup_style_cols[color_n] = g.Style.Colors[GWindowDockStyleColors[color_n]];
+
+    // Submit actual tabs
+    node->VisibleWindow = NULL;
+    for (int window_n = 0; window_n < node->Windows.Size; window_n++)
+    {
+        ImGuiWindow* window = node->Windows[window_n];
+        if (window->LastFrameActive + 1 < g.FrameCount && node_was_active)
+            continue; // FIXME: Not sure if that's still taken/useful, as windows are normally removed in DockNodeUpdateFlagsAndCollapse().
+
+        ImGuiTabItemFlags tab_item_flags = 0;
+        tab_item_flags |= window->WindowClass.TabItemFlagsOverrideSet;
+        if (window->Flags & ImGuiWindowFlags_UnsavedDocument)
+            tab_item_flags |= ImGuiTabItemFlags_UnsavedDocument;
+        if (tab_bar->Flags & ImGuiTabBarFlags_NoCloseWithMiddleMouseButton)
+            tab_item_flags |= ImGuiTabItemFlags_NoCloseWithMiddleMouseButton;
+
+        // Apply stored style overrides for the window
+        for (int color_n = 0; color_n < ImGuiWindowDockStyleCol_COUNT; color_n++)
+            g.Style.Colors[GWindowDockStyleColors[color_n]] = ColorConvertU32ToFloat4(window->DockStyle.Colors[color_n]);
+
+        // Note that TabItemEx() calls TabBarCalcTabID() so our tab item ID will ignore the current ID stack (rightly so)
+        bool tab_open = true;
+        TabItemEx(tab_bar, window->Name, window->HasCloseButton ? &tab_open : NULL, tab_item_flags, window);
+        if (!tab_open)
+            node->WantCloseTabId = window->TabId;
+        if (tab_bar->VisibleTabId == window->TabId)
+            node->VisibleWindow = window;
+
+        // Store last item data so it can be queried with IsItemXXX functions after the user Begin() call
+        window->DC.DockTabItemStatusFlags = g.LastItemData.StatusFlags;
+        window->DC.DockTabItemRect = g.LastItemData.Rect;
+
+        // Update navigation ID on menu layer
+        if (g.NavWindow && g.NavWindow->RootWindow == window && (window->DC.NavLayersActiveMask & (1 << ImGuiNavLayer_Menu)) == 0)
+            host_window->NavLastIds[1] = window->TabId;
+    }
+
+    // Restore style colors
+    for (int color_n = 0; color_n < ImGuiWindowDockStyleCol_COUNT; color_n++)
+        g.Style.Colors[GWindowDockStyleColors[color_n]] = backup_style_cols[color_n];
+
+    // Notify root of visible window (used to display title in OS task bar)
+    if (node->VisibleWindow)
+        if (is_focused || root_node->VisibleWindow == NULL)
+            root_node->VisibleWindow = node->VisibleWindow;
+
+    // Close button (after VisibleWindow was updated)
+    // Note that VisibleWindow may have been overrided by CTRL+Tabbing, so VisibleWindow->TabId may be != from tab_bar->SelectedTabId
+    const bool close_button_is_enabled = node->HasCloseButton && node->VisibleWindow && node->VisibleWindow->HasCloseButton;
+    const bool close_button_is_visible = node->HasCloseButton;
+    //const bool close_button_is_visible = close_button_is_enabled; // Most people would expect this behavior of not even showing the button (leaving a hole since we can't claim that space as other windows in the tba bar have one)
+    if (close_button_is_visible)
+    {
+        if (!close_button_is_enabled)
+        {
+            PushItemFlag(ImGuiItemFlags_Disabled, true);
+            PushStyleColor(ImGuiCol_Text, style.Colors[ImGuiCol_Text] * ImVec4(1.0f,1.0f,1.0f,0.4f));
+        }
+        if (CloseButton(host_window->GetID("#CLOSE"), close_button_pos))
+        {
+            node->WantCloseAll = true;
+            for (int n = 0; n < tab_bar->Tabs.Size; n++)
+                TabBarCloseTab(tab_bar, &tab_bar->Tabs[n]);
+        }
+        //if (IsItemActive())
+        //    focus_tab_id = tab_bar->SelectedTabId;
+        if (!close_button_is_enabled)
+        {
+            PopStyleColor();
+            PopItemFlag();
+        }
+    }
+
+    // When clicking on the title bar outside of tabs, we still focus the selected tab for that node
+    // FIXME: TabItems submitted earlier use AllowItemOverlap so we manually perform a more specific test for now (hovered || held) in order to not cover them.
+    ImGuiID title_bar_id = host_window->GetID("#TITLEBAR");
+    if (g.HoveredId == 0 || g.HoveredId == title_bar_id || g.ActiveId == title_bar_id)
+    {
+        // AllowOverlap mode required for appending into dock node tab bar,
+        // otherwise dragging window will steal HoveredId and amended tabs cannot get them.
+        bool held;
+        KeepAliveID(title_bar_id);
+        ButtonBehavior(title_bar_rect, title_bar_id, NULL, &held, ImGuiButtonFlags_AllowOverlap);
+        if (g.HoveredId == title_bar_id)
+        {
+            g.LastItemData.ID = title_bar_id;
+        }
+        if (held)
+        {
+            if (IsMouseClicked(0))
+                focus_tab_id = tab_bar->SelectedTabId;
+
+            // Forward moving request to selected window
+            if (ImGuiTabItem* tab = TabBarFindTabByID(tab_bar, tab_bar->SelectedTabId))
+                StartMouseMovingWindowOrNode(tab->Window ? tab->Window : node->HostWindow, node, false); // Undock from tab bar empty space
+        }
+    }
+
+    // Forward focus from host node to selected window
+    //if (is_focused && g.NavWindow == host_window && !g.NavWindowingTarget)
+    //    focus_tab_id = tab_bar->SelectedTabId;
+
+    // When clicked on a tab we requested focus to the docked child
+    // This overrides the value set by "forward focus from host node to selected window".
+    if (tab_bar->NextSelectedTabId)
+        focus_tab_id = tab_bar->NextSelectedTabId;
+
+    // Apply navigation focus
+    if (focus_tab_id != 0)
+        if (ImGuiTabItem* tab = TabBarFindTabByID(tab_bar, focus_tab_id))
+            if (tab->Window)
+            {
+                FocusWindow(tab->Window);
+                if (g.NavId == 0) // only init if FocusWindow() didn't restore anything.
+                    NavInitWindow(tab->Window, false);
+            }
+
+    EndTabBar();
+    PopID();
+
+    // Restore SkipItems flag
+    if (!node->IsDockSpace())
+    {
+        host_window->DC.NavLayerCurrent = ImGuiNavLayer_Main;
+        host_window->SkipItems = backup_skip_item;
+    }
+}
+
+static void ImGui::DockNodeAddTabBar(ImGuiDockNode* node)
+{
+    IM_ASSERT(node->TabBar == NULL);
+    node->TabBar = IM_NEW(ImGuiTabBar);
+}
+
+static void ImGui::DockNodeRemoveTabBar(ImGuiDockNode* node)
+{
+    if (node->TabBar == NULL)
+        return;
+    IM_DELETE(node->TabBar);
+    node->TabBar = NULL;
+}
+
+static bool DockNodeIsDropAllowedOne(ImGuiWindow* payload, ImGuiWindow* host_window)
+{
+    if (host_window->DockNodeAsHost && host_window->DockNodeAsHost->IsDockSpace() && payload->BeginOrderWithinContext < host_window->BeginOrderWithinContext)
+        return false;
+
+    ImGuiWindowClass* host_class = host_window->DockNodeAsHost ? &host_window->DockNodeAsHost->WindowClass : &host_window->WindowClass;
+    ImGuiWindowClass* payload_class = &payload->WindowClass;
+    if (host_class->ClassId != payload_class->ClassId)
+    {
+        bool pass = false;
+        if (host_class->ClassId != 0 && host_class->DockingAllowUnclassed && payload_class->ClassId == 0)
+            pass = true;
+        if (payload_class->ClassId != 0 && payload_class->DockingAllowUnclassed && host_class->ClassId == 0)
+            pass = true;
+        if (!pass)
+            return false;
+    }
+
+    // Prevent docking any window created above a popup
+    // Technically we should support it (e.g. in the case of a long-lived modal window that had fancy docking features),
+    // by e.g. adding a 'if (!ImGui::IsWindowWithinBeginStackOf(host_window, popup_window))' test.
+    // But it would requires more work on our end because the dock host windows is technically created in NewFrame()
+    // and our ->ParentXXX and ->RootXXX pointers inside windows are currently mislading or lacking.
+    ImGuiContext& g = *GImGui;
+    for (int i = g.OpenPopupStack.Size - 1; i >= 0; i--)
+        if (ImGuiWindow* popup_window = g.OpenPopupStack[i].Window)
+            if (ImGui::IsWindowWithinBeginStackOf(payload, popup_window))   // Payload is created from within a popup begin stack.
+                return false;
+
+    return true;
+}
+
+static bool ImGui::DockNodeIsDropAllowed(ImGuiWindow* host_window, ImGuiWindow* root_payload)
+{
+    if (root_payload->DockNodeAsHost && root_payload->DockNodeAsHost->IsSplitNode()) // FIXME-DOCK: Missing filtering
+        return true;
+
+    const int payload_count = root_payload->DockNodeAsHost ? root_payload->DockNodeAsHost->Windows.Size : 1;
+    for (int payload_n = 0; payload_n < payload_count; payload_n++)
+    {
+        ImGuiWindow* payload = root_payload->DockNodeAsHost ? root_payload->DockNodeAsHost->Windows[payload_n] : root_payload;
+        if (DockNodeIsDropAllowedOne(payload, host_window))
+            return true;
+    }
+    return false;
+}
+
+// window menu button == collapse button when not in a dock node.
+// FIXME: This is similar to RenderWindowTitleBarContents(), may want to share code.
+static void ImGui::DockNodeCalcTabBarLayout(const ImGuiDockNode* node, ImRect* out_title_rect, ImRect* out_tab_bar_rect, ImVec2* out_window_menu_button_pos, ImVec2* out_close_button_pos)
+{
+    ImGuiContext& g = *GImGui;
+    ImGuiStyle& style = g.Style;
+
+    ImRect r = ImRect(node->Pos.x, node->Pos.y, node->Pos.x + node->Size.x, node->Pos.y + g.FontSize + g.Style.FramePadding.y * 2.0f);
+    if (out_title_rect) { *out_title_rect = r; }
+
+    r.Min.x += style.WindowBorderSize;
+    r.Max.x -= style.WindowBorderSize;
+
+    float button_sz = g.FontSize;
+    r.Min.x += style.FramePadding.x;
+    r.Max.x -= style.FramePadding.x;
+    ImVec2 window_menu_button_pos = ImVec2(r.Min.x, r.Min.y + style.FramePadding.y);
+    if (node->HasCloseButton)
+    {
+        if (out_close_button_pos) *out_close_button_pos = ImVec2(r.Max.x - button_sz, r.Min.y + style.FramePadding.y);
+        r.Max.x -= button_sz + style.ItemInnerSpacing.x;
+    }
+    if (node->HasWindowMenuButton && style.WindowMenuButtonPosition == ImGuiDir_Left)
+    {
+        r.Min.x += button_sz + style.ItemInnerSpacing.x;
+    }
+    else if (node->HasWindowMenuButton && style.WindowMenuButtonPosition == ImGuiDir_Right)
+    {
+        window_menu_button_pos = ImVec2(r.Max.x - button_sz, r.Min.y + style.FramePadding.y);
+        r.Max.x -= button_sz + style.ItemInnerSpacing.x;
+    }
+    if (out_tab_bar_rect) { *out_tab_bar_rect = r; }
+    if (out_window_menu_button_pos) { *out_window_menu_button_pos = window_menu_button_pos; }
+}
+
+void ImGui::DockNodeCalcSplitRects(ImVec2& pos_old, ImVec2& size_old, ImVec2& pos_new, ImVec2& size_new, ImGuiDir dir, ImVec2 size_new_desired)
+{
+    ImGuiContext& g = *GImGui;
+    const float dock_spacing = g.Style.ItemInnerSpacing.x;
+    const ImGuiAxis axis = (dir == ImGuiDir_Left || dir == ImGuiDir_Right) ? ImGuiAxis_X : ImGuiAxis_Y;
+    pos_new[axis ^ 1] = pos_old[axis ^ 1];
+    size_new[axis ^ 1] = size_old[axis ^ 1];
+
+    // Distribute size on given axis (with a desired size or equally)
+    const float w_avail = size_old[axis] - dock_spacing;
+    if (size_new_desired[axis] > 0.0f && size_new_desired[axis] <= w_avail * 0.5f)
+    {
+        size_new[axis] = size_new_desired[axis];
+        size_old[axis] = IM_TRUNC(w_avail - size_new[axis]);
+    }
+    else
+    {
+        size_new[axis] = IM_TRUNC(w_avail * 0.5f);
+        size_old[axis] = IM_TRUNC(w_avail - size_new[axis]);
+    }
+
+    // Position each node
+    if (dir == ImGuiDir_Right || dir == ImGuiDir_Down)
+    {
+        pos_new[axis] = pos_old[axis] + size_old[axis] + dock_spacing;
+    }
+    else if (dir == ImGuiDir_Left || dir == ImGuiDir_Up)
+    {
+        pos_new[axis] = pos_old[axis];
+        pos_old[axis] = pos_new[axis] + size_new[axis] + dock_spacing;
+    }
+}
+
+// Retrieve the drop rectangles for a given direction or for the center + perform hit testing.
+bool ImGui::DockNodeCalcDropRectsAndTestMousePos(const ImRect& parent, ImGuiDir dir, ImRect& out_r, bool outer_docking, ImVec2* test_mouse_pos)
+{
+    ImGuiContext& g = *GImGui;
+
+    const float parent_smaller_axis = ImMin(parent.GetWidth(), parent.GetHeight());
+    const float hs_for_central_nodes = ImMin(g.FontSize * 1.5f, ImMax(g.FontSize * 0.5f, parent_smaller_axis / 8.0f));
+    float hs_w; // Half-size, longer axis
+    float hs_h; // Half-size, smaller axis
+    ImVec2 off; // Distance from edge or center
+    if (outer_docking)
+    {
+        //hs_w = ImTrunc(ImClamp(parent_smaller_axis - hs_for_central_nodes * 4.0f, g.FontSize * 0.5f, g.FontSize * 8.0f));
+        //hs_h = ImTrunc(hs_w * 0.15f);
+        //off = ImVec2(ImTrunc(parent.GetWidth() * 0.5f - GetFrameHeightWithSpacing() * 1.4f - hs_h), ImTrunc(parent.GetHeight() * 0.5f - GetFrameHeightWithSpacing() * 1.4f - hs_h));
+        hs_w = ImTrunc(hs_for_central_nodes * 1.50f);
+        hs_h = ImTrunc(hs_for_central_nodes * 0.80f);
+        off = ImTrunc(ImVec2(parent.GetWidth() * 0.5f - hs_h, parent.GetHeight() * 0.5f - hs_h));
+    }
+    else
+    {
+        hs_w = ImTrunc(hs_for_central_nodes);
+        hs_h = ImTrunc(hs_for_central_nodes * 0.90f);
+        off = ImTrunc(ImVec2(hs_w * 2.40f, hs_w * 2.40f));
+    }
+
+    ImVec2 c = ImTrunc(parent.GetCenter());
+    if      (dir == ImGuiDir_None)  { out_r = ImRect(c.x - hs_w, c.y - hs_w,         c.x + hs_w, c.y + hs_w);         }
+    else if (dir == ImGuiDir_Up)    { out_r = ImRect(c.x - hs_w, c.y - off.y - hs_h, c.x + hs_w, c.y - off.y + hs_h); }
+    else if (dir == ImGuiDir_Down)  { out_r = ImRect(c.x - hs_w, c.y + off.y - hs_h, c.x + hs_w, c.y + off.y + hs_h); }
+    else if (dir == ImGuiDir_Left)  { out_r = ImRect(c.x - off.x - hs_h, c.y - hs_w, c.x - off.x + hs_h, c.y + hs_w); }
+    else if (dir == ImGuiDir_Right) { out_r = ImRect(c.x + off.x - hs_h, c.y - hs_w, c.x + off.x + hs_h, c.y + hs_w); }
+
+    if (test_mouse_pos == NULL)
+        return false;
+
+    ImRect hit_r = out_r;
+    if (!outer_docking)
+    {
+        // Custom hit testing for the 5-way selection, designed to reduce flickering when moving diagonally between sides
+        hit_r.Expand(ImTrunc(hs_w * 0.30f));
+        ImVec2 mouse_delta = (*test_mouse_pos - c);
+        float mouse_delta_len2 = ImLengthSqr(mouse_delta);
+        float r_threshold_center = hs_w * 1.4f;
+        float r_threshold_sides = hs_w * (1.4f + 1.2f);
+        if (mouse_delta_len2 < r_threshold_center * r_threshold_center)
+            return (dir == ImGuiDir_None);
+        if (mouse_delta_len2 < r_threshold_sides * r_threshold_sides)
+            return (dir == ImGetDirQuadrantFromDelta(mouse_delta.x, mouse_delta.y));
+    }
+    return hit_r.Contains(*test_mouse_pos);
+}
+
+// host_node may be NULL if the window doesn't have a DockNode already.
+// FIXME-DOCK: This is misnamed since it's also doing the filtering.
+static void ImGui::DockNodePreviewDockSetup(ImGuiWindow* host_window, ImGuiDockNode* host_node, ImGuiWindow* payload_window, ImGuiDockNode* payload_node, ImGuiDockPreviewData* data, bool is_explicit_target, bool is_outer_docking)
+{
+    ImGuiContext& g = *GImGui;
+
+    // There is an edge case when docking into a dockspace which only has inactive nodes.
+    // In this case DockNodeTreeFindNodeByPos() will have selected a leaf node which is inactive.
+    // Because the inactive leaf node doesn't have proper pos/size yet, we'll use the root node as reference.
+    if (payload_node == NULL)
+        payload_node = payload_window->DockNodeAsHost;
+    ImGuiDockNode* ref_node_for_rect = (host_node && !host_node->IsVisible) ? DockNodeGetRootNode(host_node) : host_node;
+    if (ref_node_for_rect)
+        IM_ASSERT(ref_node_for_rect->IsVisible == true);
+
+    // Filter, figure out where we are allowed to dock
+    ImGuiDockNodeFlags src_node_flags = payload_node ? payload_node->MergedFlags : payload_window->WindowClass.DockNodeFlagsOverrideSet;
+    ImGuiDockNodeFlags dst_node_flags = host_node ? host_node->MergedFlags : host_window->WindowClass.DockNodeFlagsOverrideSet;
+    data->IsCenterAvailable = true;
+    if (is_outer_docking)
+        data->IsCenterAvailable = false;
+    else if (g.IO.ConfigDockingNoDockingOver)
+        data->IsCenterAvailable = false;
+    else if (dst_node_flags & ImGuiDockNodeFlags_NoDockingOverMe)
+        data->IsCenterAvailable = false;
+    else if (host_node && (dst_node_flags & ImGuiDockNodeFlags_NoDockingOverCentralNode) && host_node->IsCentralNode())
+        data->IsCenterAvailable = false;
+    else if ((!host_node || !host_node->IsEmpty()) && payload_node && payload_node->IsSplitNode() && (payload_node->OnlyNodeWithWindows == NULL)) // Is _visibly_ split?
+        data->IsCenterAvailable = false;
+    else if ((src_node_flags & ImGuiDockNodeFlags_NoDockingOverOther) && (!host_node || !host_node->IsEmpty()))
+        data->IsCenterAvailable = false;
+    else if ((src_node_flags & ImGuiDockNodeFlags_NoDockingOverEmpty) && host_node && host_node->IsEmpty())
+        data->IsCenterAvailable = false;
+
+    data->IsSidesAvailable = true;
+    if ((dst_node_flags & ImGuiDockNodeFlags_NoDockingSplit) || g.IO.ConfigDockingNoSplit)
+        data->IsSidesAvailable = false;
+    else if (!is_outer_docking && host_node && host_node->ParentNode == NULL && host_node->IsCentralNode())
+        data->IsSidesAvailable = false;
+    else if (src_node_flags & ImGuiDockNodeFlags_NoDockingSplitOther)
+        data->IsSidesAvailable = false;
+
+    // Build a tentative future node (reuse same structure because it is practical. Shape will be readjusted when previewing a split)
+    data->FutureNode.HasCloseButton = (host_node ? host_node->HasCloseButton : host_window->HasCloseButton) || (payload_window->HasCloseButton);
+    data->FutureNode.HasWindowMenuButton = host_node ? true : ((host_window->Flags & ImGuiWindowFlags_NoCollapse) == 0);
+    data->FutureNode.Pos = ref_node_for_rect ? ref_node_for_rect->Pos : host_window->Pos;
+    data->FutureNode.Size = ref_node_for_rect ? ref_node_for_rect->Size : host_window->Size;
+
+    // Calculate drop shapes geometry for allowed splitting directions
+    IM_ASSERT(ImGuiDir_None == -1);
+    data->SplitNode = host_node;
+    data->SplitDir = ImGuiDir_None;
+    data->IsSplitDirExplicit = false;
+    if (!host_window->Collapsed)
+        for (int dir = ImGuiDir_None; dir < ImGuiDir_COUNT; dir++)
+        {
+            if (dir == ImGuiDir_None && !data->IsCenterAvailable)
+                continue;
+            if (dir != ImGuiDir_None && !data->IsSidesAvailable)
+                continue;
+            if (DockNodeCalcDropRectsAndTestMousePos(data->FutureNode.Rect(), (ImGuiDir)dir, data->DropRectsDraw[dir+1], is_outer_docking, &g.IO.MousePos))
+            {
+                data->SplitDir = (ImGuiDir)dir;
+                data->IsSplitDirExplicit = true;
+            }
+        }
+
+    // When docking without holding Shift, we only allow and preview docking when hovering over a drop rect or over the title bar
+    data->IsDropAllowed = (data->SplitDir != ImGuiDir_None) || (data->IsCenterAvailable);
+    if (!is_explicit_target && !data->IsSplitDirExplicit && !g.IO.ConfigDockingWithShift)
+        data->IsDropAllowed = false;
+
+    // Calculate split area
+    data->SplitRatio = 0.0f;
+    if (data->SplitDir != ImGuiDir_None)
+    {
+        ImGuiDir split_dir = data->SplitDir;
+        ImGuiAxis split_axis = (split_dir == ImGuiDir_Left || split_dir == ImGuiDir_Right) ? ImGuiAxis_X : ImGuiAxis_Y;
+        ImVec2 pos_new, pos_old = data->FutureNode.Pos;
+        ImVec2 size_new, size_old = data->FutureNode.Size;
+        DockNodeCalcSplitRects(pos_old, size_old, pos_new, size_new, split_dir, payload_window->Size);
+
+        // Calculate split ratio so we can pass it down the docking request
+        float split_ratio = ImSaturate(size_new[split_axis] / data->FutureNode.Size[split_axis]);
+        data->FutureNode.Pos = pos_new;
+        data->FutureNode.Size = size_new;
+        data->SplitRatio = (split_dir == ImGuiDir_Right || split_dir == ImGuiDir_Down) ? (1.0f - split_ratio) : (split_ratio);
+    }
+}
+
+static void ImGui::DockNodePreviewDockRender(ImGuiWindow* host_window, ImGuiDockNode* host_node, ImGuiWindow* root_payload, const ImGuiDockPreviewData* data)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(g.CurrentWindow == host_window);   // Because we rely on font size to calculate tab sizes
+
+    // With this option, we only display the preview on the target viewport, and the payload viewport is made transparent.
+    // To compensate for the single layer obstructed by the payload, we'll increase the alpha of the preview nodes.
+    const bool is_transparent_payload = g.IO.ConfigDockingTransparentPayload;
+
+    // In case the two windows involved are on different viewports, we will draw the overlay on each of them.
+    int overlay_draw_lists_count = 0;
+    ImDrawList* overlay_draw_lists[2];
+    overlay_draw_lists[overlay_draw_lists_count++] = GetForegroundDrawList(host_window->Viewport);
+    if (host_window->Viewport != root_payload->Viewport && !is_transparent_payload)
+        overlay_draw_lists[overlay_draw_lists_count++] = GetForegroundDrawList(root_payload->Viewport);
+
+    // Draw main preview rectangle
+    const ImU32 overlay_col_main = GetColorU32(ImGuiCol_DockingPreview, is_transparent_payload ? 0.60f : 0.40f);
+    const ImU32 overlay_col_drop = GetColorU32(ImGuiCol_DockingPreview, is_transparent_payload ? 0.90f : 0.70f);
+    const ImU32 overlay_col_drop_hovered = GetColorU32(ImGuiCol_DockingPreview, is_transparent_payload ? 1.20f : 1.00f);
+    const ImU32 overlay_col_lines = GetColorU32(ImGuiCol_NavWindowingHighlight, is_transparent_payload ? 0.80f : 0.60f);
+
+    // Display area preview
+    const bool can_preview_tabs = (root_payload->DockNodeAsHost == NULL || root_payload->DockNodeAsHost->Windows.Size > 0);
+    if (data->IsDropAllowed)
+    {
+        ImRect overlay_rect = data->FutureNode.Rect();
+        if (data->SplitDir == ImGuiDir_None && can_preview_tabs)
+            overlay_rect.Min.y += GetFrameHeight();
+        if (data->SplitDir != ImGuiDir_None || data->IsCenterAvailable)
+            for (int overlay_n = 0; overlay_n < overlay_draw_lists_count; overlay_n++)
+                overlay_draw_lists[overlay_n]->AddRectFilled(overlay_rect.Min, overlay_rect.Max, overlay_col_main, host_window->WindowRounding, CalcRoundingFlagsForRectInRect(overlay_rect, host_window->Rect(), g.Style.DockingSeparatorSize));
+    }
+
+    // Display tab shape/label preview unless we are splitting node (it generally makes the situation harder to read)
+    if (data->IsDropAllowed && can_preview_tabs && data->SplitDir == ImGuiDir_None && data->IsCenterAvailable)
+    {
+        // Compute target tab bar geometry so we can locate our preview tabs
+        ImRect tab_bar_rect;
+        DockNodeCalcTabBarLayout(&data->FutureNode, NULL, &tab_bar_rect, NULL, NULL);
+        ImVec2 tab_pos = tab_bar_rect.Min;
+        if (host_node && host_node->TabBar)
+        {
+            if (!host_node->IsHiddenTabBar() && !host_node->IsNoTabBar())
+                tab_pos.x += host_node->TabBar->WidthAllTabs + g.Style.ItemInnerSpacing.x; // We don't use OffsetNewTab because when using non-persistent-order tab bar it is incremented with each Tab submission.
+            else
+                tab_pos.x += g.Style.ItemInnerSpacing.x + TabItemCalcSize(host_node->Windows[0]).x;
+        }
+        else if (!(host_window->Flags & ImGuiWindowFlags_DockNodeHost))
+        {
+            tab_pos.x += g.Style.ItemInnerSpacing.x + TabItemCalcSize(host_window).x; // Account for slight offset which will be added when changing from title bar to tab bar
+        }
+
+        // Draw tab shape/label preview (payload may be a loose window or a host window carrying multiple tabbed windows)
+        if (root_payload->DockNodeAsHost)
+            IM_ASSERT(root_payload->DockNodeAsHost->Windows.Size <= root_payload->DockNodeAsHost->TabBar->Tabs.Size);
+        ImGuiTabBar* tab_bar_with_payload = root_payload->DockNodeAsHost ? root_payload->DockNodeAsHost->TabBar : NULL;
+        const int payload_count = tab_bar_with_payload ? tab_bar_with_payload->Tabs.Size : 1;
+        for (int payload_n = 0; payload_n < payload_count; payload_n++)
+        {
+            // DockNode's TabBar may have non-window Tabs manually appended by user
+            ImGuiWindow* payload_window = tab_bar_with_payload ? tab_bar_with_payload->Tabs[payload_n].Window : root_payload;
+            if (tab_bar_with_payload && payload_window == NULL)
+                continue;
+            if (!DockNodeIsDropAllowedOne(payload_window, host_window))
+                continue;
+
+            // Calculate the tab bounding box for each payload window
+            ImVec2 tab_size = TabItemCalcSize(payload_window);
+            ImRect tab_bb(tab_pos.x, tab_pos.y, tab_pos.x + tab_size.x, tab_pos.y + tab_size.y);
+            tab_pos.x += tab_size.x + g.Style.ItemInnerSpacing.x;
+            const ImU32 overlay_col_text = GetColorU32(payload_window->DockStyle.Colors[ImGuiWindowDockStyleCol_Text]);
+            const ImU32 overlay_col_tabs = GetColorU32(payload_window->DockStyle.Colors[ImGuiWindowDockStyleCol_TabSelected]);
+            const ImU32 overlay_col_unsaved_marker = GetColorU32(payload_window->DockStyle.Colors[ImGuiWindowDockStyleCol_UnsavedMarker]);
+            PushStyleColor(ImGuiCol_Text, overlay_col_text);
+            PushStyleColor(ImGuiCol_UnsavedMarker, overlay_col_unsaved_marker);
+            for (int overlay_n = 0; overlay_n < overlay_draw_lists_count; overlay_n++)
+            {
+                ImGuiTabItemFlags tab_flags = (payload_window->Flags & ImGuiWindowFlags_UnsavedDocument) ? ImGuiTabItemFlags_UnsavedDocument : 0;
+                if (!tab_bar_rect.Contains(tab_bb))
+                    overlay_draw_lists[overlay_n]->PushClipRect(tab_bar_rect.Min, tab_bar_rect.Max);
+                TabItemBackground(overlay_draw_lists[overlay_n], tab_bb, tab_flags, overlay_col_tabs);
+                TabItemLabelAndCloseButton(overlay_draw_lists[overlay_n], tab_bb, tab_flags, g.Style.FramePadding, payload_window->Name, 0, 0, false, NULL, NULL);
+                if (!tab_bar_rect.Contains(tab_bb))
+                    overlay_draw_lists[overlay_n]->PopClipRect();
+            }
+            PopStyleColor(2);
+        }
+    }
+
+    // Display drop boxes
+    const float overlay_rounding = ImMax(3.0f, g.Style.FrameRounding);
+    for (int dir = ImGuiDir_None; dir < ImGuiDir_COUNT; dir++)
+    {
+        if (!data->DropRectsDraw[dir + 1].IsInverted())
+        {
+            ImRect draw_r = data->DropRectsDraw[dir + 1];
+            ImRect draw_r_in = draw_r;
+            draw_r_in.Expand(-2.0f);
+            ImU32 overlay_col = (data->SplitDir == (ImGuiDir)dir && data->IsSplitDirExplicit) ? overlay_col_drop_hovered : overlay_col_drop;
+            for (int overlay_n = 0; overlay_n < overlay_draw_lists_count; overlay_n++)
+            {
+                ImVec2 center = ImFloor(draw_r_in.GetCenter());
+                overlay_draw_lists[overlay_n]->AddRectFilled(draw_r.Min, draw_r.Max, overlay_col, overlay_rounding);
+                overlay_draw_lists[overlay_n]->AddRect(draw_r_in.Min, draw_r_in.Max, overlay_col_lines, overlay_rounding);
+                if (dir == ImGuiDir_Left || dir == ImGuiDir_Right)
+                    overlay_draw_lists[overlay_n]->AddLine(ImVec2(center.x, draw_r_in.Min.y), ImVec2(center.x, draw_r_in.Max.y), overlay_col_lines);
+                if (dir == ImGuiDir_Up || dir == ImGuiDir_Down)
+                    overlay_draw_lists[overlay_n]->AddLine(ImVec2(draw_r_in.Min.x, center.y), ImVec2(draw_r_in.Max.x, center.y), overlay_col_lines);
+            }
+        }
+
+        // Stop after ImGuiDir_None
+        if ((host_node && (host_node->MergedFlags & ImGuiDockNodeFlags_NoDockingSplit)) || g.IO.ConfigDockingNoSplit)
+            return;
+    }
+}
+
+//-----------------------------------------------------------------------------
+// Docking: ImGuiDockNode Tree manipulation functions
+//-----------------------------------------------------------------------------
+// - DockNodeTreeSplit()
+// - DockNodeTreeMerge()
+// - DockNodeTreeUpdatePosSize()
+// - DockNodeTreeUpdateSplitterFindTouchingNode()
+// - DockNodeTreeUpdateSplitter()
+// - DockNodeTreeFindFallbackLeafNode()
+// - DockNodeTreeFindNodeByPos()
+//-----------------------------------------------------------------------------
+
+void ImGui::DockNodeTreeSplit(ImGuiContext* ctx, ImGuiDockNode* parent_node, ImGuiAxis split_axis, int split_inheritor_child_idx, float split_ratio, ImGuiDockNode* new_node)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(split_axis != ImGuiAxis_None);
+
+    ImGuiDockNode* child_0 = (new_node && split_inheritor_child_idx != 0) ? new_node : DockContextAddNode(ctx, 0);
+    child_0->ParentNode = parent_node;
+
+    ImGuiDockNode* child_1 = (new_node && split_inheritor_child_idx != 1) ? new_node : DockContextAddNode(ctx, 0);
+    child_1->ParentNode = parent_node;
+
+    ImGuiDockNode* child_inheritor = (split_inheritor_child_idx == 0) ? child_0 : child_1;
+    DockNodeMoveChildNodes(child_inheritor, parent_node);
+    parent_node->ChildNodes[0] = child_0;
+    parent_node->ChildNodes[1] = child_1;
+    parent_node->ChildNodes[split_inheritor_child_idx]->VisibleWindow = parent_node->VisibleWindow;
+    parent_node->SplitAxis = split_axis;
+    parent_node->VisibleWindow = NULL;
+    parent_node->AuthorityForPos = parent_node->AuthorityForSize = ImGuiDataAuthority_DockNode;
+
+    float size_avail = (parent_node->Size[split_axis] - g.Style.DockingSeparatorSize);
+    size_avail = ImMax(size_avail, g.Style.WindowMinSize[split_axis] * 2.0f);
+    IM_ASSERT(size_avail > 0.0f); // If you created a node manually with DockBuilderAddNode(), you need to also call DockBuilderSetNodeSize() before splitting.
+    child_0->SizeRef = child_1->SizeRef = parent_node->Size;
+    child_0->SizeRef[split_axis] = ImTrunc(size_avail * split_ratio);
+    child_1->SizeRef[split_axis] = ImTrunc(size_avail - child_0->SizeRef[split_axis]);
+
+    DockNodeMoveWindows(parent_node->ChildNodes[split_inheritor_child_idx], parent_node);
+    DockSettingsRenameNodeReferences(parent_node->ID, parent_node->ChildNodes[split_inheritor_child_idx]->ID);
+    DockNodeUpdateHasCentralNodeChild(DockNodeGetRootNode(parent_node));
+    DockNodeTreeUpdatePosSize(parent_node, parent_node->Pos, parent_node->Size);
+
+    // Flags transfer (e.g. this is where we transfer the ImGuiDockNodeFlags_CentralNode property)
+    child_0->SharedFlags = parent_node->SharedFlags & ImGuiDockNodeFlags_SharedFlagsInheritMask_;
+    child_1->SharedFlags = parent_node->SharedFlags & ImGuiDockNodeFlags_SharedFlagsInheritMask_;
+    child_inheritor->LocalFlags = parent_node->LocalFlags & ImGuiDockNodeFlags_LocalFlagsTransferMask_;
+    parent_node->LocalFlags &= ~ImGuiDockNodeFlags_LocalFlagsTransferMask_;
+    child_0->UpdateMergedFlags();
+    child_1->UpdateMergedFlags();
+    parent_node->UpdateMergedFlags();
+    if (child_inheritor->IsCentralNode())
+        DockNodeGetRootNode(parent_node)->CentralNode = child_inheritor;
+}
+
+void ImGui::DockNodeTreeMerge(ImGuiContext* ctx, ImGuiDockNode* parent_node, ImGuiDockNode* merge_lead_child)
+{
+    // When called from DockContextProcessUndockNode() it is possible that one of the child is NULL.
+    ImGuiContext& g = *GImGui;
+    ImGuiDockNode* child_0 = parent_node->ChildNodes[0];
+    ImGuiDockNode* child_1 = parent_node->ChildNodes[1];
+    IM_ASSERT(child_0 || child_1);
+    IM_ASSERT(merge_lead_child == child_0 || merge_lead_child == child_1);
+    if ((child_0 && child_0->Windows.Size > 0) || (child_1 && child_1->Windows.Size > 0))
+    {
+        IM_ASSERT(parent_node->TabBar == NULL);
+        IM_ASSERT(parent_node->Windows.Size == 0);
+    }
+    IMGUI_DEBUG_LOG_DOCKING("[docking] DockNodeTreeMerge: 0x%08X + 0x%08X back into parent 0x%08X\n", child_0 ? child_0->ID : 0, child_1 ? child_1->ID : 0, parent_node->ID);
+
+    ImVec2 backup_last_explicit_size = parent_node->SizeRef;
+    DockNodeMoveChildNodes(parent_node, merge_lead_child);
+    if (child_0)
+    {
+        DockNodeMoveWindows(parent_node, child_0); // Generally only 1 of the 2 child node will have windows
+        DockSettingsRenameNodeReferences(child_0->ID, parent_node->ID);
+    }
+    if (child_1)
+    {
+        DockNodeMoveWindows(parent_node, child_1);
+        DockSettingsRenameNodeReferences(child_1->ID, parent_node->ID);
+    }
+    DockNodeApplyPosSizeToWindows(parent_node);
+    parent_node->AuthorityForPos = parent_node->AuthorityForSize = parent_node->AuthorityForViewport = ImGuiDataAuthority_Auto;
+    parent_node->VisibleWindow = merge_lead_child->VisibleWindow;
+    parent_node->SizeRef = backup_last_explicit_size;
+
+    // Flags transfer
+    parent_node->LocalFlags &= ~ImGuiDockNodeFlags_LocalFlagsTransferMask_; // Preserve Dockspace flag
+    parent_node->LocalFlags |= (child_0 ? child_0->LocalFlags : 0) & ImGuiDockNodeFlags_LocalFlagsTransferMask_;
+    parent_node->LocalFlags |= (child_1 ? child_1->LocalFlags : 0) & ImGuiDockNodeFlags_LocalFlagsTransferMask_;
+    parent_node->LocalFlagsInWindows = (child_0 ? child_0->LocalFlagsInWindows : 0) | (child_1 ? child_1->LocalFlagsInWindows : 0); // FIXME: Would be more consistent to update from actual windows
+    parent_node->UpdateMergedFlags();
+
+    if (child_0)
+        DockContextDeleteNode(ctx, child_0);
+    if (child_1)
+        DockContextDeleteNode(ctx, child_1);
+}
+
+// Update Pos/Size for a node hierarchy (don't affect child Windows yet)
+// (Depth-first, Pre-Order)
+void ImGui::DockNodeTreeUpdatePosSize(ImGuiDockNode* node, ImVec2 pos, ImVec2 size, ImGuiDockNode* only_write_to_single_node)
+{
+    // During the regular dock node update we write to all nodes.
+    // 'only_write_to_single_node' is only set when turning a node visible mid-frame and we need its size right-away.
+    ImGuiContext& g = *GImGui;
+    const bool write_to_node = only_write_to_single_node == NULL || only_write_to_single_node == node;
+    if (write_to_node)
+    {
+        node->Pos = pos;
+        node->Size = size;
+    }
+
+    if (node->IsLeafNode())
+        return;
+
+    ImGuiDockNode* child_0 = node->ChildNodes[0];
+    ImGuiDockNode* child_1 = node->ChildNodes[1];
+    ImVec2 child_0_pos = pos, child_1_pos = pos;
+    ImVec2 child_0_size = size, child_1_size = size;
+
+    const bool child_0_is_toward_single_node = (only_write_to_single_node != NULL && DockNodeIsInHierarchyOf(only_write_to_single_node, child_0));
+    const bool child_1_is_toward_single_node = (only_write_to_single_node != NULL && DockNodeIsInHierarchyOf(only_write_to_single_node, child_1));
+    const bool child_0_is_or_will_be_visible = child_0->IsVisible || child_0_is_toward_single_node;
+    const bool child_1_is_or_will_be_visible = child_1->IsVisible || child_1_is_toward_single_node;
+
+    if (child_0_is_or_will_be_visible && child_1_is_or_will_be_visible)
+    {
+        const float spacing = g.Style.DockingSeparatorSize;
+        const ImGuiAxis axis = (ImGuiAxis)node->SplitAxis;
+        const float size_avail = ImMax(size[axis] - spacing, 0.0f);
+
+        // Size allocation policy
+        // 1) The first 0..WindowMinSize[axis]*2 are allocated evenly to both windows.
+        const float size_min_each = ImTrunc(ImMin(size_avail, g.Style.WindowMinSize[axis] * 2.0f) * 0.5f);
+
+        // FIXME: Blocks 2) and 3) are essentially doing nearly the same thing.
+        // Difference are: write-back to SizeRef; application of a minimum size; rounding before ImTrunc()
+        // Clarify and rework differences between Size & SizeRef and purpose of WantLockSizeOnce
+
+        // 2) Process locked absolute size (during a splitter resize we preserve the child of nodes not touching the splitter edge)
+        if (child_0->WantLockSizeOnce && !child_1->WantLockSizeOnce)
+        {
+            child_0_size[axis] = child_0->SizeRef[axis] = ImMin(size_avail - 1.0f, child_0->Size[axis]);
+            child_1_size[axis] = child_1->SizeRef[axis] = (size_avail - child_0_size[axis]);
+            IM_ASSERT(child_0->SizeRef[axis] > 0.0f && child_1->SizeRef[axis] > 0.0f);
+        }
+        else if (child_1->WantLockSizeOnce && !child_0->WantLockSizeOnce)
+        {
+            child_1_size[axis] = child_1->SizeRef[axis] = ImMin(size_avail - 1.0f, child_1->Size[axis]);
+            child_0_size[axis] = child_0->SizeRef[axis] = (size_avail - child_1_size[axis]);
+            IM_ASSERT(child_0->SizeRef[axis] > 0.0f && child_1->SizeRef[axis] > 0.0f);
+        }
+        else if (child_0->WantLockSizeOnce && child_1->WantLockSizeOnce)
+        {
+            // FIXME-DOCK: We cannot honor the requested size, so apply ratio.
+            // Currently this path will only be taken if code programmatically sets WantLockSizeOnce
+            float split_ratio = child_0_size[axis] / (child_0_size[axis] + child_1_size[axis]);
+            child_0_size[axis] = child_0->SizeRef[axis] = ImTrunc(size_avail * split_ratio);
+            child_1_size[axis] = child_1->SizeRef[axis] = (size_avail - child_0_size[axis]);
+            IM_ASSERT(child_0->SizeRef[axis] > 0.0f && child_1->SizeRef[axis] > 0.0f);
+        }
+
+        // 3) If one window is the central node (~ use remaining space, should be made explicit!), use explicit size from the other, and remainder for the central node
+        else if (child_0->SizeRef[axis] != 0.0f && child_1->HasCentralNodeChild)
+        {
+            child_0_size[axis] = ImMin(size_avail - size_min_each, child_0->SizeRef[axis]);
+            child_1_size[axis] = (size_avail - child_0_size[axis]);
+        }
+        else if (child_1->SizeRef[axis] != 0.0f && child_0->HasCentralNodeChild)
+        {
+            child_1_size[axis] = ImMin(size_avail - size_min_each, child_1->SizeRef[axis]);
+            child_0_size[axis] = (size_avail - child_1_size[axis]);
+        }
+        else
+        {
+            // 4) Otherwise distribute according to the relative ratio of each SizeRef value
+            float split_ratio = child_0->SizeRef[axis] / (child_0->SizeRef[axis] + child_1->SizeRef[axis]);
+            child_0_size[axis] = ImMax(size_min_each, ImTrunc(size_avail * split_ratio + 0.5f));
+            child_1_size[axis] = (size_avail - child_0_size[axis]);
+        }
+
+        child_1_pos[axis] += spacing + child_0_size[axis];
+    }
+
+    if (only_write_to_single_node == NULL)
+        child_0->WantLockSizeOnce = child_1->WantLockSizeOnce = false;
+
+    const bool child_0_recurse = only_write_to_single_node ? child_0_is_toward_single_node : child_0->IsVisible;
+    const bool child_1_recurse = only_write_to_single_node ? child_1_is_toward_single_node : child_1->IsVisible;
+    if (child_0_recurse)
+        DockNodeTreeUpdatePosSize(child_0, child_0_pos, child_0_size);
+    if (child_1_recurse)
+        DockNodeTreeUpdatePosSize(child_1, child_1_pos, child_1_size);
+}
+
+static void DockNodeTreeUpdateSplitterFindTouchingNode(ImGuiDockNode* node, ImGuiAxis axis, int side, ImVector<ImGuiDockNode*>* touching_nodes)
+{
+    if (node->IsLeafNode())
+    {
+        touching_nodes->push_back(node);
+        return;
+    }
+    if (node->ChildNodes[0]->IsVisible)
+        if (node->SplitAxis != axis || side == 0 || !node->ChildNodes[1]->IsVisible)
+            DockNodeTreeUpdateSplitterFindTouchingNode(node->ChildNodes[0], axis, side, touching_nodes);
+    if (node->ChildNodes[1]->IsVisible)
+        if (node->SplitAxis != axis || side == 1 || !node->ChildNodes[0]->IsVisible)
+            DockNodeTreeUpdateSplitterFindTouchingNode(node->ChildNodes[1], axis, side, touching_nodes);
+}
+
+// (Depth-First, Pre-Order)
+void ImGui::DockNodeTreeUpdateSplitter(ImGuiDockNode* node)
+{
+    if (node->IsLeafNode())
+        return;
+
+    ImGuiContext& g = *GImGui;
+
+    ImGuiDockNode* child_0 = node->ChildNodes[0];
+    ImGuiDockNode* child_1 = node->ChildNodes[1];
+    if (child_0->IsVisible && child_1->IsVisible)
+    {
+        // Bounding box of the splitter cover the space between both nodes (w = Spacing, h = Size[xy^1] for when splitting horizontally)
+        const ImGuiAxis axis = (ImGuiAxis)node->SplitAxis;
+        IM_ASSERT(axis != ImGuiAxis_None);
+        ImRect bb;
+        bb.Min = child_0->Pos;
+        bb.Max = child_1->Pos;
+        bb.Min[axis] += child_0->Size[axis];
+        bb.Max[axis ^ 1] += child_1->Size[axis ^ 1];
+        //if (g.IO.KeyCtrl) GetForegroundDrawList(g.CurrentWindow->Viewport)->AddRect(bb.Min, bb.Max, IM_COL32(255,0,255,255));
+
+        const ImGuiDockNodeFlags merged_flags = child_0->MergedFlags | child_1->MergedFlags; // Merged flags for BOTH childs
+        const ImGuiDockNodeFlags no_resize_axis_flag = (axis == ImGuiAxis_X) ? ImGuiDockNodeFlags_NoResizeX : ImGuiDockNodeFlags_NoResizeY;
+        if ((merged_flags & ImGuiDockNodeFlags_NoResize) || (merged_flags & no_resize_axis_flag))
+        {
+            ImGuiWindow* window = g.CurrentWindow;
+            window->DrawList->AddRectFilled(bb.Min, bb.Max, GetColorU32(ImGuiCol_Separator), g.Style.FrameRounding);
+        }
+        else
+        {
+            //bb.Min[axis] += 1; // Display a little inward so highlight doesn't connect with nearby tabs on the neighbor node.
+            //bb.Max[axis] -= 1;
+            PushID(node->ID);
+
+            // Find resizing limits by gathering list of nodes that are touching the splitter line.
+            ImVector<ImGuiDockNode*> touching_nodes[2];
+            float min_size = g.Style.WindowMinSize[axis];
+            float resize_limits[2];
+            resize_limits[0] = node->ChildNodes[0]->Pos[axis] + min_size;
+            resize_limits[1] = node->ChildNodes[1]->Pos[axis] + node->ChildNodes[1]->Size[axis] - min_size;
+
+            ImGuiID splitter_id = GetID("##Splitter");
+            if (g.ActiveId == splitter_id) // Only process when splitter is active
+            {
+                DockNodeTreeUpdateSplitterFindTouchingNode(child_0, axis, 1, &touching_nodes[0]);
+                DockNodeTreeUpdateSplitterFindTouchingNode(child_1, axis, 0, &touching_nodes[1]);
+                for (int touching_node_n = 0; touching_node_n < touching_nodes[0].Size; touching_node_n++)
+                    resize_limits[0] = ImMax(resize_limits[0], touching_nodes[0][touching_node_n]->Rect().Min[axis] + min_size);
+                for (int touching_node_n = 0; touching_node_n < touching_nodes[1].Size; touching_node_n++)
+                    resize_limits[1] = ImMin(resize_limits[1], touching_nodes[1][touching_node_n]->Rect().Max[axis] - min_size);
+
+                // [DEBUG] Render touching nodes & limits
+                /*
+                ImDrawList* draw_list = node->HostWindow ? GetForegroundDrawList(node->HostWindow) : GetForegroundDrawList(GetMainViewport());
+                for (int n = 0; n < 2; n++)
+                {
+                    for (int touching_node_n = 0; touching_node_n < touching_nodes[n].Size; touching_node_n++)
+                        draw_list->AddRect(touching_nodes[n][touching_node_n]->Pos, touching_nodes[n][touching_node_n]->Pos + touching_nodes[n][touching_node_n]->Size, IM_COL32(0, 255, 0, 255));
+                    if (axis == ImGuiAxis_X)
+                        draw_list->AddLine(ImVec2(resize_limits[n], node->ChildNodes[n]->Pos.y), ImVec2(resize_limits[n], node->ChildNodes[n]->Pos.y + node->ChildNodes[n]->Size.y), IM_COL32(255, 0, 255, 255), 3.0f);
+                    else
+                        draw_list->AddLine(ImVec2(node->ChildNodes[n]->Pos.x, resize_limits[n]), ImVec2(node->ChildNodes[n]->Pos.x + node->ChildNodes[n]->Size.x, resize_limits[n]), IM_COL32(255, 0, 255, 255), 3.0f);
+                }
+                */
+            }
+
+            // Use a short delay before highlighting the splitter (and changing the mouse cursor) in order for regular mouse movement to not highlight many splitters
+            float cur_size_0 = child_0->Size[axis];
+            float cur_size_1 = child_1->Size[axis];
+            float min_size_0 = resize_limits[0] - child_0->Pos[axis];
+            float min_size_1 = child_1->Pos[axis] + child_1->Size[axis] - resize_limits[1];
+            ImU32 bg_col = GetColorU32(ImGuiCol_WindowBg);
+            if (SplitterBehavior(bb, GetID("##Splitter"), axis, &cur_size_0, &cur_size_1, min_size_0, min_size_1, g.WindowsBorderHoverPadding, WINDOWS_RESIZE_FROM_EDGES_FEEDBACK_TIMER, bg_col))
+            {
+                if (touching_nodes[0].Size > 0 && touching_nodes[1].Size > 0)
+                {
+                    child_0->Size[axis] = child_0->SizeRef[axis] = cur_size_0;
+                    child_1->Pos[axis] -= cur_size_1 - child_1->Size[axis];
+                    child_1->Size[axis] = child_1->SizeRef[axis] = cur_size_1;
+
+                    // Lock the size of every node that is a sibling of the node we are touching
+                    // This might be less desirable if we can merge sibling of a same axis into the same parental level.
+                    for (int side_n = 0; side_n < 2; side_n++)
+                        for (int touching_node_n = 0; touching_node_n < touching_nodes[side_n].Size; touching_node_n++)
+                        {
+                            ImGuiDockNode* touching_node = touching_nodes[side_n][touching_node_n];
+                            //ImDrawList* draw_list = node->HostWindow ? GetForegroundDrawList(node->HostWindow) : GetForegroundDrawList(GetMainViewport());
+                            //draw_list->AddRect(touching_node->Pos, touching_node->Pos + touching_node->Size, IM_COL32(255, 128, 0, 255));
+                            while (touching_node->ParentNode != node)
+                            {
+                                if (touching_node->ParentNode->SplitAxis == axis)
+                                {
+                                    // Mark other node so its size will be preserved during the upcoming call to DockNodeTreeUpdatePosSize().
+                                    ImGuiDockNode* node_to_preserve = touching_node->ParentNode->ChildNodes[side_n];
+                                    node_to_preserve->WantLockSizeOnce = true;
+                                    //draw_list->AddRect(touching_node->Pos, touching_node->Rect().Max, IM_COL32(255, 0, 0, 255));
+                                    //draw_list->AddRectFilled(node_to_preserve->Pos, node_to_preserve->Rect().Max, IM_COL32(0, 255, 0, 100));
+                                }
+                                touching_node = touching_node->ParentNode;
+                            }
+                        }
+
+                    DockNodeTreeUpdatePosSize(child_0, child_0->Pos, child_0->Size);
+                    DockNodeTreeUpdatePosSize(child_1, child_1->Pos, child_1->Size);
+                    MarkIniSettingsDirty();
+                }
+            }
+            PopID();
+        }
+    }
+
+    if (child_0->IsVisible)
+        DockNodeTreeUpdateSplitter(child_0);
+    if (child_1->IsVisible)
+        DockNodeTreeUpdateSplitter(child_1);
+}
+
+ImGuiDockNode* ImGui::DockNodeTreeFindFallbackLeafNode(ImGuiDockNode* node)
+{
+    if (node->IsLeafNode())
+        return node;
+    if (ImGuiDockNode* leaf_node = DockNodeTreeFindFallbackLeafNode(node->ChildNodes[0]))
+        return leaf_node;
+    if (ImGuiDockNode* leaf_node = DockNodeTreeFindFallbackLeafNode(node->ChildNodes[1]))
+        return leaf_node;
+    return NULL;
+}
+
+ImGuiDockNode* ImGui::DockNodeTreeFindVisibleNodeByPos(ImGuiDockNode* node, ImVec2 pos)
+{
+    if (!node->IsVisible)
+        return NULL;
+
+    const float dock_spacing = 0.0f;// g.Style.ItemInnerSpacing.x; // FIXME: Relation to DOCKING_SPLITTER_SIZE?
+    ImRect r(node->Pos, node->Pos + node->Size);
+    r.Expand(dock_spacing * 0.5f);
+    bool inside = r.Contains(pos);
+    if (!inside)
+        return NULL;
+
+    if (node->IsLeafNode())
+        return node;
+    if (ImGuiDockNode* hovered_node = DockNodeTreeFindVisibleNodeByPos(node->ChildNodes[0], pos))
+        return hovered_node;
+    if (ImGuiDockNode* hovered_node = DockNodeTreeFindVisibleNodeByPos(node->ChildNodes[1], pos))
+        return hovered_node;
+
+    // This means we are hovering over the splitter/spacing of a parent node
+    return node;
+}
+
+//-----------------------------------------------------------------------------
+// Docking: Public Functions (SetWindowDock, DockSpace, DockSpaceOverViewport)
+//-----------------------------------------------------------------------------
+// - SetWindowDock() [Internal]
+// - DockSpace()
+// - DockSpaceOverViewport()
+//-----------------------------------------------------------------------------
+
+// [Internal] Called via SetNextWindowDockID()
+void ImGui::SetWindowDock(ImGuiWindow* window, ImGuiID dock_id, ImGuiCond cond)
+{
+    // Test condition (NB: bit 0 is always true) and clear flags for next time
+    if (cond && (window->SetWindowDockAllowFlags & cond) == 0)
+        return;
+    window->SetWindowDockAllowFlags &= ~(ImGuiCond_Once | ImGuiCond_FirstUseEver | ImGuiCond_Appearing);
+
+    if (window->DockId == dock_id)
+        return;
+
+    // If the user attempt to set a dock id that is a split node, we'll dig within to find a suitable docking spot
+    ImGuiContext& g = *GImGui;
+    if (ImGuiDockNode* new_node = DockContextFindNodeByID(&g, dock_id))
+        if (new_node->IsSplitNode())
+        {
+            // Policy: Find central node or latest focused node. We first move back to our root node.
+            new_node = DockNodeGetRootNode(new_node);
+            if (new_node->CentralNode)
+            {
+                IM_ASSERT(new_node->CentralNode->IsCentralNode());
+                dock_id = new_node->CentralNode->ID;
+            }
+            else
+            {
+                dock_id = new_node->LastFocusedNodeId;
+            }
+        }
+
+    if (window->DockId == dock_id)
+        return;
+
+    if (window->DockNode)
+        DockNodeRemoveWindow(window->DockNode, window, 0);
+    window->DockId = dock_id;
+}
+
+// Create an explicit dockspace node within an existing window. Also expose dock node flags and creates a CentralNode by default.
+// The Central Node is always displayed even when empty and shrink/extend according to the requested size of its neighbors.
+// DockSpace() needs to be submitted _before_ any window they can host. If you use a dockspace, submit it early in your app.
+// When ImGuiDockNodeFlags_KeepAliveOnly is set, nothing is submitted in the current window (function may be called from any location).
+ImGuiID ImGui::DockSpace(ImGuiID dockspace_id, const ImVec2& size_arg, ImGuiDockNodeFlags flags, const ImGuiWindowClass* window_class)
+{
+    ImGuiContext& g = *GImGui;
+    ImGuiWindow* window = GetCurrentWindowRead();
+    if (!(g.IO.ConfigFlags & ImGuiConfigFlags_DockingEnable))
+        return 0;
+
+    // Early out if parent window is hidden/collapsed
+    // This is faster but also DockNodeUpdateTabBar() relies on TabBarLayout() running (which won't if SkipItems=true) to set NextSelectedTabId = 0). See #2960.
+    // If for whichever reason this is causing problem we would need to ensure that DockNodeUpdateTabBar() ends up clearing NextSelectedTabId even if SkipItems=true.
+    if (window->SkipItems)
+        flags |= ImGuiDockNodeFlags_KeepAliveOnly;
+    if ((flags & ImGuiDockNodeFlags_KeepAliveOnly) == 0)
+        window = GetCurrentWindow(); // call to set window->WriteAccessed = true;
+
+    IM_ASSERT((flags & ImGuiDockNodeFlags_DockSpace) == 0); // Flag is automatically set by DockSpace() as LocalFlags, not SharedFlags!
+    IM_ASSERT((flags & ImGuiDockNodeFlags_CentralNode) == 0); // Flag is automatically set by DockSpace() as LocalFlags, not SharedFlags! (#8145)
+
+    IM_ASSERT(dockspace_id != 0);
+    ImGuiDockNode* node = DockContextFindNodeByID(&g, dockspace_id);
+    if (node == NULL)
+    {
+        IMGUI_DEBUG_LOG_DOCKING("[docking] DockSpace: dockspace node 0x%08X created\n", dockspace_id);
+        node = DockContextAddNode(&g, dockspace_id);
+        node->SetLocalFlags(ImGuiDockNodeFlags_CentralNode);
+    }
+    if (window_class && window_class->ClassId != node->WindowClass.ClassId)
+        IMGUI_DEBUG_LOG_DOCKING("[docking] DockSpace: dockspace node 0x%08X: setup WindowClass 0x%08X -> 0x%08X\n", dockspace_id, node->WindowClass.ClassId, window_class->ClassId);
+    node->SharedFlags = flags;
+    node->WindowClass = window_class ? *window_class : ImGuiWindowClass();
+
+    // When a DockSpace transitioned form implicit to explicit this may be called a second time
+    // It is possible that the node has already been claimed by a docked window which appeared before the DockSpace() node, so we overwrite IsDockSpace again.
+    if (node->LastFrameActive == g.FrameCount && !(flags & ImGuiDockNodeFlags_KeepAliveOnly))
+    {
+        IM_ASSERT(node->IsDockSpace() == false && "Cannot call DockSpace() twice a frame with the same ID");
+        node->SetLocalFlags(node->LocalFlags | ImGuiDockNodeFlags_DockSpace);
+        return dockspace_id;
+    }
+    node->SetLocalFlags(node->LocalFlags | ImGuiDockNodeFlags_DockSpace);
+
+    // Keep alive mode, this is allow windows docked into this node so stay docked even if they are not visible
+    if (flags & ImGuiDockNodeFlags_KeepAliveOnly)
+    {
+        node->LastFrameAlive = g.FrameCount;
+        return dockspace_id;
+    }
+
+    const ImVec2 content_avail = GetContentRegionAvail();
+    ImVec2 size = ImTrunc(size_arg);
+    if (size.x <= 0.0f)
+        size.x = ImMax(content_avail.x + size.x, 4.0f); // Arbitrary minimum child size (0.0f causing too much issues)
+    if (size.y <= 0.0f)
+        size.y = ImMax(content_avail.y + size.y, 4.0f);
+    IM_ASSERT(size.x > 0.0f && size.y > 0.0f);
+
+    node->Pos = window->DC.CursorPos;
+    node->Size = node->SizeRef = size;
+    SetNextWindowPos(node->Pos);
+    SetNextWindowSize(node->Size);
+    g.NextWindowData.PosUndock = false;
+
+    // FIXME-DOCK: Why do we need a child window to host a dockspace, could we host it in the existing window?
+    // FIXME-DOCK: What is the reason for not simply calling BeginChild()? (OK to have a reason but should be commented)
+    ImGuiWindowFlags window_flags = ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_DockNodeHost;
+    window_flags |= ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoCollapse | ImGuiWindowFlags_NoTitleBar;
+    window_flags |= ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoScrollWithMouse;
+    window_flags |= ImGuiWindowFlags_NoBackground;
+
+    char title[256];
+    ImFormatString(title, IM_COUNTOF(title), "%s/DockSpace_%08X", window->Name, dockspace_id);
+
+    PushStyleVar(ImGuiStyleVar_ChildBorderSize, 0.0f);
+    Begin(title, NULL, window_flags);
+    PopStyleVar();
+
+    ImGuiWindow* host_window = g.CurrentWindow;
+    DockNodeSetupHostWindow(node, host_window);
+    host_window->ChildId = window->GetID(title);
+    node->OnlyNodeWithWindows = NULL;
+
+    IM_ASSERT(node->IsRootNode());
+
+    // We need to handle the rare case were a central node is missing.
+    // This can happen if the node was first created manually with DockBuilderAddNode() but _without_ the ImGuiDockNodeFlags_Dockspace.
+    // Doing it correctly would set the _CentralNode flags, which would then propagate according to subsequent split.
+    // It would also be ambiguous to attempt to assign a central node while there are split nodes, so we wait until there's a single node remaining.
+    // The specific sub-property of _CentralNode we are interested in recovering here is the "Don't delete when empty" property,
+    // as it doesn't make sense for an empty dockspace to not have this property.
+    if (node->IsLeafNode() && !node->IsCentralNode())
+        node->SetLocalFlags(node->LocalFlags | ImGuiDockNodeFlags_CentralNode);
+
+    // Update the node
+    DockNodeUpdate(node);
+
+    End();
+
+    ImRect bb(node->Pos, node->Pos + size);
+    ItemSize(size);
+    ItemAdd(bb, dockspace_id, NULL, ImGuiItemFlags_NoNav); // Not a nav point (could be, would need to draw the nav rect and replicate/refactor activation from BeginChild(), but seems like CTRL+Tab works better here?)
+    if ((g.LastItemData.StatusFlags & ImGuiItemStatusFlags_HoveredRect) && IsWindowChildOf(g.HoveredWindow, host_window, false, true)) // To fullfill IsItemHovered(), similar to EndChild()
+        g.LastItemData.StatusFlags |= ImGuiItemStatusFlags_HoveredWindow;
+
+    return dockspace_id;
+}
+
+// Tips: Use with ImGuiDockNodeFlags_PassthruCentralNode!
+// The limitation with this call is that your window won't have a local menu bar, but you can also use BeginMainMenuBar().
+// Even though we could pass window flags, it would also require the user to be able to call BeginMenuBar() somehow meaning we can't Begin/End in a single function.
+// If you really want a menu bar inside the same window as the one hosting the dockspace, you will need to copy this code somewhere and tweak it.
+ImGuiID ImGui::DockSpaceOverViewport(ImGuiID dockspace_id, const ImGuiViewport* viewport, ImGuiDockNodeFlags dockspace_flags, const ImGuiWindowClass* window_class)
+{
+    if (viewport == NULL)
+        viewport = GetMainViewport();
+
+    // Submit a window filling the entire viewport
+    SetNextWindowPos(viewport->WorkPos);
+    SetNextWindowSize(viewport->WorkSize);
+    SetNextWindowViewport(viewport->ID);
+
+    ImGuiWindowFlags host_window_flags = 0;
+    host_window_flags |= ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoCollapse | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoDocking;
+    host_window_flags |= ImGuiWindowFlags_NoBringToFrontOnFocus | ImGuiWindowFlags_NoNavFocus;
+    if (dockspace_flags & ImGuiDockNodeFlags_PassthruCentralNode)
+        host_window_flags |= ImGuiWindowFlags_NoBackground;
+
+    // FIXME-OPT: When using ImGuiDockNodeFlags_KeepAliveOnly with DockSpaceOverViewport() we might be able to spare submitting the window,
+    // since DockSpace() with that flag doesn't need a window. We'd only need to compute the default ID accordingly.
+    if (dockspace_flags & ImGuiDockNodeFlags_KeepAliveOnly)
+        host_window_flags |= ImGuiWindowFlags_NoMouseInputs;
+
+    char label[32];
+    ImFormatString(label, IM_COUNTOF(label), "WindowOverViewport_%08X", viewport->ID);
+
+    PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
+    PushStyleVar(ImGuiStyleVar_WindowBorderSize, 0.0f);
+    PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(0.0f, 0.0f));
+    Begin(label, NULL, host_window_flags);
+    PopStyleVar(3);
+
+    // Submit the dockspace
+    if (dockspace_id == 0)
+        dockspace_id = GetID("DockSpace");
+    DockSpace(dockspace_id, ImVec2(0.0f, 0.0f), dockspace_flags, window_class);
+
+    End();
+
+    return dockspace_id;
+}
+
+//-----------------------------------------------------------------------------
+// Docking: Builder Functions
+//-----------------------------------------------------------------------------
+// Very early end-user API to manipulate dock nodes.
+// Only available in imgui_internal.h. Expect this API to change/break!
+// It is expected that those functions are all called _before_ the dockspace node submission.
+//-----------------------------------------------------------------------------
+// - DockBuilderDockWindow()
+// - DockBuilderGetNode()
+// - DockBuilderSetNodePos()
+// - DockBuilderSetNodeSize()
+// - DockBuilderAddNode()
+// - DockBuilderRemoveNode()
+// - DockBuilderRemoveNodeChildNodes()
+// - DockBuilderRemoveNodeDockedWindows()
+// - DockBuilderSplitNode()
+// - DockBuilderCopyNodeRec()
+// - DockBuilderCopyNode()
+// - DockBuilderCopyWindowSettings()
+// - DockBuilderCopyDockSpace()
+// - DockBuilderFinish()
+//-----------------------------------------------------------------------------
+
+void ImGui::DockBuilderDockWindow(const char* window_name, ImGuiID node_id)
+{
+    // We don't preserve relative order of multiple docked windows (by clearing DockOrder back to -1)
+    ImGuiContext& g = *GImGui; IM_UNUSED(g);
+    IMGUI_DEBUG_LOG_DOCKING("[docking] DockBuilderDockWindow '%s' to node 0x%08X\n", window_name, node_id);
+    ImGuiID window_id = ImHashStr(window_name);
+    if (ImGuiWindow* window = FindWindowByID(window_id))
+    {
+        // Apply to created window
+        ImGuiID prev_node_id = window->DockId;
+        SetWindowDock(window, node_id, ImGuiCond_Always);
+        if (window->DockId != prev_node_id)
+            window->DockOrder = -1;
+    }
+    else
+    {
+        // Apply to settings
+        ImGuiWindowSettings* settings = FindWindowSettingsByID(window_id);
+        if (settings == NULL)
+            settings = CreateNewWindowSettings(window_name);
+        if (settings->DockId != node_id)
+            settings->DockOrder = -1;
+        settings->DockId = node_id;
+    }
+}
+
+ImGuiDockNode* ImGui::DockBuilderGetNode(ImGuiID node_id)
+{
+    ImGuiContext& g = *GImGui;
+    return DockContextFindNodeByID(&g, node_id);
+}
+
+void ImGui::DockBuilderSetNodePos(ImGuiID node_id, ImVec2 pos)
+{
+    ImGuiContext& g = *GImGui;
+    ImGuiDockNode* node = DockContextFindNodeByID(&g, node_id);
+    if (node == NULL)
+        return;
+    node->Pos = pos;
+    node->AuthorityForPos = ImGuiDataAuthority_DockNode;
+}
+
+void ImGui::DockBuilderSetNodeSize(ImGuiID node_id, ImVec2 size)
+{
+    ImGuiContext& g = *GImGui;
+    ImGuiDockNode* node = DockContextFindNodeByID(&g, node_id);
+    if (node == NULL)
+        return;
+    IM_ASSERT(size.x > 0.0f && size.y > 0.0f);
+    node->Size = node->SizeRef = size;
+    node->AuthorityForSize = ImGuiDataAuthority_DockNode;
+}
+
+// Make sure to use the ImGuiDockNodeFlags_DockSpace flag to create a dockspace node! Otherwise this will create a floating node!
+// - Floating node: you can then call DockBuilderSetNodePos()/DockBuilderSetNodeSize() to position and size the floating node.
+// - Dockspace node: calling DockBuilderSetNodePos() is unnecessary.
+// - If you intend to split a node immediately after creation using DockBuilderSplitNode(), make sure to call DockBuilderSetNodeSize() beforehand!
+//   For various reason, the splitting code currently needs a base size otherwise space may not be allocated as precisely as you would expect.
+// - Use (id == 0) to let the system allocate a node identifier.
+// - Existing node with a same id will be removed.
+ImGuiID ImGui::DockBuilderAddNode(ImGuiID node_id, ImGuiDockNodeFlags flags)
+{
+    ImGuiContext& g = *GImGui; IM_UNUSED(g);
+    IMGUI_DEBUG_LOG_DOCKING("[docking] DockBuilderAddNode 0x%08X flags=%08X\n", node_id, flags);
+
+    if (node_id != 0)
+        DockBuilderRemoveNode(node_id);
+
+    ImGuiDockNode* node = NULL;
+    if (flags & ImGuiDockNodeFlags_DockSpace)
+    {
+        DockSpace(node_id, ImVec2(0, 0), (flags & ~ImGuiDockNodeFlags_DockSpace) | ImGuiDockNodeFlags_KeepAliveOnly);
+        node = DockContextFindNodeByID(&g, node_id);
+    }
+    else
+    {
+        node = DockContextAddNode(&g, node_id);
+        node->SetLocalFlags(flags);
+    }
+    node->LastFrameAlive = g.FrameCount;   // Set this otherwise BeginDocked will undock during the same frame.
+    return node->ID;
+}
+
+void ImGui::DockBuilderRemoveNode(ImGuiID node_id)
+{
+    ImGuiContext& g = *GImGui; IM_UNUSED(g);
+    IMGUI_DEBUG_LOG_DOCKING("[docking] DockBuilderRemoveNode 0x%08X\n", node_id);
+
+    ImGuiDockNode* node = DockContextFindNodeByID(&g, node_id);
+    if (node == NULL)
+        return;
+    DockBuilderRemoveNodeDockedWindows(node_id, true);
+    DockBuilderRemoveNodeChildNodes(node_id);
+    // Node may have moved or deleted if e.g. any merge happened
+    node = DockContextFindNodeByID(&g, node_id);
+    if (node == NULL)
+        return;
+    if (node->IsCentralNode() && node->ParentNode)
+        node->ParentNode->SetLocalFlags(node->ParentNode->LocalFlags | ImGuiDockNodeFlags_CentralNode);
+    DockContextRemoveNode(&g, node, true);
+}
+
+// root_id = 0 to remove all, root_id != 0 to remove child of given node.
+void ImGui::DockBuilderRemoveNodeChildNodes(ImGuiID root_id)
+{
+    ImGuiContext& g = *GImGui;
+    ImGuiDockContext* dc = &g.DockContext;
+
+    ImGuiDockNode* root_node = root_id ? DockContextFindNodeByID(&g, root_id) : NULL;
+    if (root_id && root_node == NULL)
+        return;
+    bool has_central_node = false;
+
+    ImGuiDataAuthority backup_root_node_authority_for_pos = root_node ? root_node->AuthorityForPos : ImGuiDataAuthority_Auto;
+    ImGuiDataAuthority backup_root_node_authority_for_size = root_node ? root_node->AuthorityForSize : ImGuiDataAuthority_Auto;
+
+    // Process active windows
+    ImVector<ImGuiDockNode*> nodes_to_remove;
+    for (int n = 0; n < dc->Nodes.Data.Size; n++)
+        if (ImGuiDockNode* node = (ImGuiDockNode*)dc->Nodes.Data[n].val_p)
+        {
+            bool want_removal = (root_id == 0) || (node->ID != root_id && DockNodeGetRootNode(node)->ID == root_id);
+            if (want_removal)
+            {
+                if (node->IsCentralNode())
+                    has_central_node = true;
+                if (root_id != 0)
+                    DockContextQueueNotifyRemovedNode(&g, node);
+                if (root_node)
+                {
+                    DockNodeMoveWindows(root_node, node);
+                    DockSettingsRenameNodeReferences(node->ID, root_node->ID);
+                }
+                nodes_to_remove.push_back(node);
+            }
+        }
+
+    // DockNodeMoveWindows->DockNodeAddWindow will normally set those when reaching two windows (which is only adequate during interactive merge)
+    // Make sure we don't lose our current pos/size. (FIXME-DOCK: Consider tidying up that code in DockNodeAddWindow instead)
+    if (root_node)
+    {
+        root_node->AuthorityForPos = backup_root_node_authority_for_pos;
+        root_node->AuthorityForSize = backup_root_node_authority_for_size;
+    }
+
+    // Apply to settings
+    for (ImGuiWindowSettings* settings = g.SettingsWindows.begin(); settings != NULL; settings = g.SettingsWindows.next_chunk(settings))
+        if (ImGuiID window_settings_dock_id = settings->DockId)
+            for (int n = 0; n < nodes_to_remove.Size; n++)
+                if (nodes_to_remove[n]->ID == window_settings_dock_id)
+                {
+                    settings->DockId = root_id;
+                    break;
+                }
+
+    // Not really efficient, but easier to destroy a whole hierarchy considering DockContextRemoveNode is attempting to merge nodes
+    if (nodes_to_remove.Size > 1)
+        ImQsort(nodes_to_remove.Data, nodes_to_remove.Size, sizeof(ImGuiDockNode*), DockNodeComparerDepthMostFirst);
+    for (int n = 0; n < nodes_to_remove.Size; n++)
+        DockContextRemoveNode(&g, nodes_to_remove[n], false);
+
+    if (root_id == 0)
+    {
+        dc->Nodes.Clear();
+        dc->Requests.clear();
+    }
+    else if (has_central_node)
+    {
+        root_node->CentralNode = root_node;
+        root_node->SetLocalFlags(root_node->LocalFlags | ImGuiDockNodeFlags_CentralNode);
+    }
+}
+
+void ImGui::DockBuilderRemoveNodeDockedWindows(ImGuiID root_id, bool clear_settings_refs)
+{
+    // Clear references in settings
+    ImGuiContext& g = *GImGui;
+    if (clear_settings_refs)
+    {
+        for (ImGuiWindowSettings* settings = g.SettingsWindows.begin(); settings != NULL; settings = g.SettingsWindows.next_chunk(settings))
+        {
+            bool want_removal = (root_id == 0) || (settings->DockId == root_id);
+            if (!want_removal && settings->DockId != 0)
+                if (ImGuiDockNode* node = DockContextFindNodeByID(&g, settings->DockId))
+                    if (DockNodeGetRootNode(node)->ID == root_id)
+                        want_removal = true;
+            if (want_removal)
+                settings->DockId = 0;
+        }
+    }
+
+    // Clear references in windows
+    for (int n = 0; n < g.Windows.Size; n++)
+    {
+        ImGuiWindow* window = g.Windows[n];
+        bool want_removal = (root_id == 0) || (window->DockNode && DockNodeGetRootNode(window->DockNode)->ID == root_id) || (window->DockNodeAsHost && window->DockNodeAsHost->ID == root_id);
+        if (want_removal)
+        {
+            const ImGuiID backup_dock_id = window->DockId;
+            IM_UNUSED(backup_dock_id);
+            DockContextProcessUndockWindow(&g, window, clear_settings_refs);
+            if (!clear_settings_refs)
+                IM_ASSERT(window->DockId == backup_dock_id);
+        }
+    }
+}
+
+// If 'out_id_at_dir' or 'out_id_at_opposite_dir' are non NULL, the function will write out the ID of the two new nodes created.
+// Return value is ID of the node at the specified direction, so same as (*out_id_at_dir) if that pointer is set.
+// FIXME-DOCK: We are not exposing nor using split_outer.
+ImGuiID ImGui::DockBuilderSplitNode(ImGuiID id, ImGuiDir split_dir, float size_ratio_for_node_at_dir, ImGuiID* out_id_at_dir, ImGuiID* out_id_at_opposite_dir)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(split_dir != ImGuiDir_None);
+    IMGUI_DEBUG_LOG_DOCKING("[docking] DockBuilderSplitNode: node 0x%08X, split_dir %d\n", id, split_dir);
+
+    ImGuiDockNode* node = DockContextFindNodeByID(&g, id);
+    if (node == NULL)
+    {
+        IM_ASSERT(node != NULL);
+        return 0;
+    }
+
+    ImGuiDockRequest req;
+    req.Type = ImGuiDockRequestType_Split;
+    req.DockTargetWindow = NULL;
+    req.DockTargetNode = node;
+    req.DockPayload = NULL;
+    req.DockSplitDir = split_dir;
+    req.DockSplitRatio = ImSaturate((split_dir == ImGuiDir_Left || split_dir == ImGuiDir_Up) ? size_ratio_for_node_at_dir : 1.0f - size_ratio_for_node_at_dir);
+    req.DockSplitOuter = false;
+    DockContextProcessDock(&g, &req);
+
+    ImGuiID id_at_dir = node->ChildNodes[(split_dir == ImGuiDir_Left || split_dir == ImGuiDir_Up) ? 0 : 1]->ID;
+    ImGuiID id_at_opposite_dir = node->ChildNodes[(split_dir == ImGuiDir_Left || split_dir == ImGuiDir_Up) ? 1 : 0]->ID;
+    if (out_id_at_dir)
+        *out_id_at_dir = id_at_dir;
+    if (out_id_at_opposite_dir)
+        *out_id_at_opposite_dir = id_at_opposite_dir;
+    return id_at_dir;
+}
+
+static ImGuiDockNode* DockBuilderCopyNodeRec(ImGuiDockNode* src_node, ImGuiID dst_node_id_if_known, ImVector<ImGuiID>* out_node_remap_pairs)
+{
+    ImGuiContext& g = *GImGui;
+    ImGuiDockNode* dst_node = ImGui::DockContextAddNode(&g, dst_node_id_if_known);
+    dst_node->SharedFlags = src_node->SharedFlags;
+    dst_node->LocalFlags = src_node->LocalFlags;
+    dst_node->LocalFlagsInWindows = ImGuiDockNodeFlags_None;
+    dst_node->Pos = src_node->Pos;
+    dst_node->Size = src_node->Size;
+    dst_node->SizeRef = src_node->SizeRef;
+    dst_node->SplitAxis = src_node->SplitAxis;
+    dst_node->UpdateMergedFlags();
+
+    out_node_remap_pairs->push_back(src_node->ID);
+    out_node_remap_pairs->push_back(dst_node->ID);
+
+    for (int child_n = 0; child_n < IM_COUNTOF(src_node->ChildNodes); child_n++)
+        if (src_node->ChildNodes[child_n])
+        {
+            dst_node->ChildNodes[child_n] = DockBuilderCopyNodeRec(src_node->ChildNodes[child_n], 0, out_node_remap_pairs);
+            dst_node->ChildNodes[child_n]->ParentNode = dst_node;
+        }
+
+    IMGUI_DEBUG_LOG_DOCKING("[docking] Fork node %08X -> %08X (%d childs)\n", src_node->ID, dst_node->ID, dst_node->IsSplitNode() ? 2 : 0);
+    return dst_node;
+}
+
+void ImGui::DockBuilderCopyNode(ImGuiID src_node_id, ImGuiID dst_node_id, ImVector<ImGuiID>* out_node_remap_pairs)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(src_node_id != 0);
+    IM_ASSERT(dst_node_id != 0);
+    IM_ASSERT(out_node_remap_pairs != NULL);
+
+    DockBuilderRemoveNode(dst_node_id);
+
+    ImGuiDockNode* src_node = DockContextFindNodeByID(&g, src_node_id);
+    IM_ASSERT(src_node != NULL);
+
+    out_node_remap_pairs->clear();
+    DockBuilderCopyNodeRec(src_node, dst_node_id, out_node_remap_pairs);
+
+    IM_ASSERT((out_node_remap_pairs->Size % 2) == 0);
+}
+
+void ImGui::DockBuilderCopyWindowSettings(const char* src_name, const char* dst_name)
+{
+    ImGuiWindow* src_window = FindWindowByName(src_name);
+    if (src_window == NULL)
+        return;
+    if (ImGuiWindow* dst_window = FindWindowByName(dst_name))
+    {
+        dst_window->Pos = src_window->Pos;
+        dst_window->Size = src_window->Size;
+        dst_window->SizeFull = src_window->SizeFull;
+        dst_window->Collapsed = src_window->Collapsed;
+    }
+    else
+    {
+        ImGuiWindowSettings* dst_settings = FindWindowSettingsByID(ImHashStr(dst_name));
+        if (!dst_settings)
+            dst_settings = CreateNewWindowSettings(dst_name);
+        ImVec2ih window_pos_2ih = ImVec2ih(src_window->Pos);
+        if (src_window->ViewportId != 0 && src_window->ViewportId != IMGUI_VIEWPORT_DEFAULT_ID)
+        {
+            dst_settings->ViewportPos = window_pos_2ih;
+            dst_settings->ViewportId = src_window->ViewportId;
+            dst_settings->Pos = ImVec2ih(0, 0);
+        }
+        else
+        {
+            dst_settings->Pos = window_pos_2ih;
+        }
+        dst_settings->Size = ImVec2ih(src_window->SizeFull);
+        dst_settings->Collapsed = src_window->Collapsed;
+    }
+}
+
+// FIXME: Will probably want to change this signature, in particular how the window remapping pairs are passed.
+void ImGui::DockBuilderCopyDockSpace(ImGuiID src_dockspace_id, ImGuiID dst_dockspace_id, ImVector<const char*>* in_window_remap_pairs)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(src_dockspace_id != 0);
+    IM_ASSERT(dst_dockspace_id != 0);
+    IM_ASSERT(in_window_remap_pairs != NULL);
+    IM_ASSERT((in_window_remap_pairs->Size % 2) == 0);
+
+    // Duplicate entire dock
+    // FIXME: When overwriting dst_dockspace_id, windows that aren't part of our dockspace window class but that are docked in a same node will be split apart,
+    // whereas we could attempt to at least keep them together in a new, same floating node.
+    ImVector<ImGuiID> node_remap_pairs;
+    DockBuilderCopyNode(src_dockspace_id, dst_dockspace_id, &node_remap_pairs);
+
+    // Attempt to transition all the upcoming windows associated to dst_dockspace_id into the newly created hierarchy of dock nodes
+    // (The windows associated to src_dockspace_id are staying in place)
+    ImVector<ImGuiID> src_windows;
+    for (int remap_window_n = 0; remap_window_n < in_window_remap_pairs->Size; remap_window_n += 2)
+    {
+        const char* src_window_name = (*in_window_remap_pairs)[remap_window_n];
+        const char* dst_window_name = (*in_window_remap_pairs)[remap_window_n + 1];
+        ImGuiID src_window_id = ImHashStr(src_window_name);
+        src_windows.push_back(src_window_id);
+
+        // Search in the remapping tables
+        ImGuiID src_dock_id = 0;
+        if (ImGuiWindow* src_window = FindWindowByID(src_window_id))
+            src_dock_id = src_window->DockId;
+        else if (ImGuiWindowSettings* src_window_settings = FindWindowSettingsByID(src_window_id))
+            src_dock_id = src_window_settings->DockId;
+        ImGuiID dst_dock_id = 0;
+        for (int dock_remap_n = 0; dock_remap_n < node_remap_pairs.Size; dock_remap_n += 2)
+            if (node_remap_pairs[dock_remap_n] == src_dock_id)
+            {
+                dst_dock_id = node_remap_pairs[dock_remap_n + 1];
+                //node_remap_pairs[dock_remap_n] = node_remap_pairs[dock_remap_n + 1] = 0; // Clear
+                break;
+            }
+
+        if (dst_dock_id != 0)
+        {
+            // Docked windows gets redocked into the new node hierarchy.
+            IMGUI_DEBUG_LOG_DOCKING("[docking] Remap live window '%s' 0x%08X -> '%s' 0x%08X\n", src_window_name, src_dock_id, dst_window_name, dst_dock_id);
+            DockBuilderDockWindow(dst_window_name, dst_dock_id);
+        }
+        else
+        {
+            // Floating windows gets their settings transferred (regardless of whether the new window already exist or not)
+            // When this is leading to a Copy and not a Move, we would get two overlapping floating windows. Could we possibly dock them together?
+            IMGUI_DEBUG_LOG_DOCKING("[docking] Remap window settings '%s' -> '%s'\n", src_window_name, dst_window_name);
+            DockBuilderCopyWindowSettings(src_window_name, dst_window_name);
+        }
+    }
+
+    // Anything else in the source nodes of 'node_remap_pairs' are windows that are not included in the remapping list.
+    // Find those windows and move to them to the cloned dock node. This may be optional?
+    // Dock those are a second step as undocking would invalidate source dock nodes.
+    struct DockRemainingWindowTask { ImGuiWindow* Window; ImGuiID DockId; DockRemainingWindowTask(ImGuiWindow* window, ImGuiID dock_id) { Window = window; DockId = dock_id; } };
+    ImVector<DockRemainingWindowTask> dock_remaining_windows;
+    for (int dock_remap_n = 0; dock_remap_n < node_remap_pairs.Size; dock_remap_n += 2)
+        if (ImGuiID src_dock_id = node_remap_pairs[dock_remap_n])
+        {
+            ImGuiID dst_dock_id = node_remap_pairs[dock_remap_n + 1];
+            ImGuiDockNode* node = DockBuilderGetNode(src_dock_id);
+            for (int window_n = 0; window_n < node->Windows.Size; window_n++)
+            {
+                ImGuiWindow* window = node->Windows[window_n];
+                if (src_windows.contains(window->ID))
+                    continue;
+
+                // Docked windows gets redocked into the new node hierarchy.
+                IMGUI_DEBUG_LOG_DOCKING("[docking] Remap window '%s' %08X -> %08X\n", window->Name, src_dock_id, dst_dock_id);
+                dock_remaining_windows.push_back(DockRemainingWindowTask(window, dst_dock_id));
+            }
+        }
+    for (const DockRemainingWindowTask& task : dock_remaining_windows)
+        DockBuilderDockWindow(task.Window->Name, task.DockId);
+}
+
+// FIXME-DOCK: This is awkward because in series of split user is likely to loose access to its root node.
+void ImGui::DockBuilderFinish(ImGuiID root_id)
+{
+    ImGuiContext& g = *GImGui;
+    //DockContextRebuild(&g);
+    DockContextBuildAddWindowsToNodes(&g, root_id);
+}
+
+//-----------------------------------------------------------------------------
+// Docking: Begin/End Support Functions (called from Begin/End)
+//-----------------------------------------------------------------------------
+// - GetWindowAlwaysWantOwnTabBar()
+// - DockContextBindNodeToWindow()
+// - BeginDocked()
+// - BeginDockableDragDropSource()
+// - BeginDockableDragDropTarget()
+//-----------------------------------------------------------------------------
+
+bool ImGui::GetWindowAlwaysWantOwnTabBar(ImGuiWindow* window)
+{
+    ImGuiContext& g = *GImGui;
+    if (g.IO.ConfigDockingAlwaysTabBar || window->WindowClass.DockingAlwaysTabBar)
+        if ((window->Flags & (ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoDocking)) == 0)
+            if (!window->IsFallbackWindow)    // We don't support AlwaysTabBar on the fallback/implicit window to avoid unused dock-node overhead/noise
+                return true;
+    return false;
+}
+
+static ImGuiDockNode* ImGui::DockContextBindNodeToWindow(ImGuiContext* ctx, ImGuiWindow* window)
+{
+    ImGuiContext& g = *ctx;
+    ImGuiDockNode* node = DockContextFindNodeByID(ctx, window->DockId);
+    IM_ASSERT(window->DockNode == NULL);
+
+    // We should not be docking into a split node (SetWindowDock should avoid this)
+    if (node && node->IsSplitNode())
+    {
+        DockContextProcessUndockWindow(ctx, window);
+        return NULL;
+    }
+
+    // Create node
+    if (node == NULL)
+    {
+        node = DockContextAddNode(ctx, window->DockId);
+        node->AuthorityForPos = node->AuthorityForSize = node->AuthorityForViewport = ImGuiDataAuthority_Window;
+        node->LastFrameAlive = g.FrameCount;
+    }
+
+    // If the node just turned visible and is part of a hierarchy, it doesn't have a Size assigned by DockNodeTreeUpdatePosSize() yet,
+    // so we're forcing a Pos/Size update from the first ancestor that is already visible (often it will be the root node).
+    // If we don't do this, the window will be assigned a zero-size on its first frame, which won't ideally warm up the layout.
+    // This is a little wonky because we don't normally update the Pos/Size of visible node mid-frame.
+    if (!node->IsVisible)
+    {
+        ImGuiDockNode* ancestor_node = node;
+        while (!ancestor_node->IsVisible && ancestor_node->ParentNode)
+            ancestor_node = ancestor_node->ParentNode;
+        IM_ASSERT(ancestor_node->Size.x > 0.0f && ancestor_node->Size.y > 0.0f);
+        DockNodeUpdateHasCentralNodeChild(DockNodeGetRootNode(ancestor_node));
+        DockNodeTreeUpdatePosSize(ancestor_node, ancestor_node->Pos, ancestor_node->Size, node);
+    }
+
+    // Add window to node
+    bool node_was_visible = node->IsVisible;
+    DockNodeAddWindow(node, window, true);
+    node->IsVisible = node_was_visible; // Don't mark visible right away (so DockContextEndFrame() doesn't render it, maybe other side effects? will see)
+    IM_ASSERT(node == window->DockNode);
+    return node;
+}
+
+static void StoreDockStyleForWindow(ImGuiWindow* window)
+{
+    ImGuiContext& g = *GImGui;
+    for (int color_n = 0; color_n < ImGuiWindowDockStyleCol_COUNT; color_n++)
+        window->DockStyle.Colors[color_n] = ImGui::ColorConvertFloat4ToU32(g.Style.Colors[GWindowDockStyleColors[color_n]]);
+}
+
+void ImGui::BeginDocked(ImGuiWindow* window, bool* p_open)
+{
+    ImGuiContext& g = *GImGui;
+
+    // Specific extra processing for fallback window (#9151), could be in Begin() as well.
+    if (window->IsFallbackWindow && !window->WasActive)
+    {
+        DockNodeHideWindowDuringHostWindowCreation(window);
+        return;
+    }
+
+    const bool auto_dock_node = GetWindowAlwaysWantOwnTabBar(window);
+    if (auto_dock_node)
+    {
+        if (window->DockId == 0)
+        {
+            IM_ASSERT(window->DockNode == NULL);
+            window->DockId = DockContextGenNodeID(&g);
+        }
+    }
+    else
+    {
+        // Calling SetNextWindowPos() undock windows by default (by setting PosUndock)
+        bool want_undock = false;
+        want_undock |= (window->Flags & ImGuiWindowFlags_NoDocking) != 0;
+        want_undock |= (g.NextWindowData.HasFlags & ImGuiNextWindowDataFlags_HasPos) && (window->SetWindowPosAllowFlags & g.NextWindowData.PosCond) && g.NextWindowData.PosUndock;
+        if (want_undock)
+        {
+            DockContextProcessUndockWindow(&g, window);
+            return;
+        }
+    }
+
+    // Bind to our dock node
+    ImGuiDockNode* node = window->DockNode;
+    if (node != NULL)
+        IM_ASSERT(window->DockId == node->ID);
+    if (window->DockId != 0 && node == NULL)
+    {
+        node = DockContextBindNodeToWindow(&g, window);
+        if (node == NULL)
+            return;
+    }
+
+#if 0
+    // Undock if the ImGuiDockNodeFlags_NoDockingInCentralNode got set
+    if (node->IsCentralNode && (node->Flags & ImGuiDockNodeFlags_NoDockingInCentralNode))
+    {
+        DockContextProcessUndockWindow(ctx, window);
+        return;
+    }
+#endif
+
+    // Undock if our dockspace node disappeared
+    // Note how we are testing for LastFrameAlive and NOT LastFrameActive. A DockSpace node can be maintained alive while being inactive with ImGuiDockNodeFlags_KeepAliveOnly.
+    if (node->LastFrameAlive < g.FrameCount)
+    {
+        // If the window has been orphaned, transition the docknode to an implicit node processed in DockContextNewFrameUpdateDocking()
+        ImGuiDockNode* root_node = DockNodeGetRootNode(node);
+        if (root_node->LastFrameAlive < g.FrameCount)
+            DockContextProcessUndockWindow(&g, window);
+        else
+            window->DockIsActive = true;
+        return;
+    }
+
+    // Store style overrides
+    StoreDockStyleForWindow(window);
+
+    // Fast path return. It is common for windows to hold on a persistent DockId but be the only visible window,
+    // and never create neither a host window neither a tab bar.
+    // FIXME-DOCK: replace ->HostWindow NULL compare with something more explicit (~was initially intended as a first frame test)
+    if (node->HostWindow == NULL)
+    {
+        if (node->State == ImGuiDockNodeState_HostWindowHiddenBecauseWindowsAreResizing)
+            window->DockIsActive = true;
+        if (node->Windows.Size > 1 && window->Appearing) // Only hide appearing window
+            DockNodeHideWindowDuringHostWindowCreation(window);
+        return;
+    }
+
+    // We can have zero-sized nodes (e.g. children of a small-size dockspace)
+    IM_ASSERT(node->HostWindow);
+    IM_ASSERT(node->IsLeafNode());
+    IM_ASSERT(node->Size.x >= 0.0f && node->Size.y >= 0.0f);
+    node->State = ImGuiDockNodeState_HostWindowVisible;
+
+    // Undock if we are submitted earlier than the host window
+    if (!(node->MergedFlags & ImGuiDockNodeFlags_KeepAliveOnly) && window->BeginOrderWithinContext < node->HostWindow->BeginOrderWithinContext)
+    {
+        DockContextProcessUndockWindow(&g, window);
+        return;
+    }
+
+    // Position/Size window
+    SetNextWindowPos(node->Pos);
+    SetNextWindowSize(node->Size);
+    g.NextWindowData.PosUndock = false; // Cancel implicit undocking of SetNextWindowPos()
+    window->DockIsActive = true;
+    window->DockNodeIsVisible = true;
+    window->DockTabIsVisible = false;
+    if (node->MergedFlags & ImGuiDockNodeFlags_KeepAliveOnly)
+        return;
+
+    // When the window is selected we mark it as visible.
+    if (node->VisibleWindow == window)
+        window->DockTabIsVisible = true;
+
+    // Update window flag
+    IM_ASSERT((window->Flags & ImGuiWindowFlags_ChildWindow) == 0);
+    window->Flags |= ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_NoResize;
+    window->ChildFlags |= ImGuiChildFlags_AlwaysUseWindowPadding;
+    if (node->IsHiddenTabBar() || node->IsNoTabBar())
+        window->Flags |= ImGuiWindowFlags_NoTitleBar;
+    else
+        window->Flags &= ~ImGuiWindowFlags_NoTitleBar;      // Clear the NoTitleBar flag in case the user set it: confusingly enough we need a title bar height so we are correctly offset, but it won't be displayed!
+
+    // Save new dock order only if the window has been visible once already
+    // This allows multiple windows to be created in the same frame and have their respective dock orders preserved.
+    if (node->TabBar && window->WasActive)
+        window->DockOrder = (short)DockNodeGetTabOrder(window);
+
+    if ((node->WantCloseAll || node->WantCloseTabId == window->TabId) && p_open != NULL)
+        *p_open = false;
+
+    // Update ChildId to allow returning from Child to Parent with Escape
+    ImGuiWindow* parent_window = window->DockNode->HostWindow;
+    window->ChildId = parent_window->GetID(window->Name);
+}
+
+void ImGui::BeginDockableDragDropSource(ImGuiWindow* window)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(g.ActiveId == window->MoveId);
+    IM_ASSERT(g.MovingWindow == window);
+    IM_ASSERT(g.CurrentWindow == window);
+
+    // 0: Hold SHIFT to disable docking, 1: Hold SHIFT to enable docking.
+    if (g.IO.ConfigDockingWithShift != g.IO.KeyShift)
+    {
+        // When ConfigDockingWithShift is set, display a tooltip to increase UI affordance.
+        // We cannot set for HoveredWindowUnderMovingWindow != NULL here, as it is only valid/useful when drag and drop is already active
+        // (because of the 'is_mouse_dragging_with_an_expected_destination' logic in UpdateViewportsNewFrame() function)
+        IM_ASSERT(g.NextWindowData.HasFlags == 0);
+        if (g.IO.ConfigDockingWithShift && g.MouseStationaryTimer >= 1.0f && g.ActiveId >= 1.0f)
+            SetTooltip("%s", LocalizeGetMsg(ImGuiLocKey_DockingHoldShiftToDock));
+        return;
+    }
+
+    g.LastItemData.ID = window->MoveId;
+    window = window->RootWindowDockTree;
+    IM_ASSERT((window->Flags & ImGuiWindowFlags_NoDocking) == 0);
+    bool is_drag_docking = (g.IO.ConfigDockingWithShift) || ImRect(0, 0, window->SizeFull.x, GetFrameHeight()).Contains(g.ActiveIdClickOffset); // FIXME-DOCKING: Need to make this stateful and explicit
+    ImGuiDragDropFlags drag_drop_flags = ImGuiDragDropFlags_SourceNoPreviewTooltip | ImGuiDragDropFlags_SourceNoHoldToOpenOthers | ImGuiDragDropFlags_PayloadAutoExpire | ImGuiDragDropFlags_PayloadNoCrossContext | ImGuiDragDropFlags_PayloadNoCrossProcess;
+    if (is_drag_docking && BeginDragDropSource(drag_drop_flags))
+    {
+        SetDragDropPayload(IMGUI_PAYLOAD_TYPE_WINDOW, &window, sizeof(window));
+        EndDragDropSource();
+        StoreDockStyleForWindow(window); // Store style overrides while dragging (even when not docked) because docking preview may need it.
+    }
+}
+
+void ImGui::BeginDockableDragDropTarget(ImGuiWindow* window)
+{
+    ImGuiContext& g = *GImGui;
+
+    //IM_ASSERT(window->RootWindowDockTree == window); // May also be a DockSpace
+    IM_ASSERT((window->Flags & ImGuiWindowFlags_NoDocking) == 0);
+    if (!g.DragDropActive)
+        return;
+    //GetForegroundDrawList(window)->AddRect(window->Pos, window->Pos + window->Size, IM_COL32(255, 255, 0, 255));
+    if (!BeginDragDropTargetCustom(window->Rect(), window->ID))
+        return;
+
+    // Peek into the payload before calling AcceptDragDropPayload() so we can handle overlapping dock nodes with filtering
+    // (this is a little unusual pattern, normally most code would call AcceptDragDropPayload directly)
+    const ImGuiPayload* payload = &g.DragDropPayload;
+    if (!payload->IsDataType(IMGUI_PAYLOAD_TYPE_WINDOW) || !DockNodeIsDropAllowed(window, *(ImGuiWindow**)payload->Data))
+    {
+        EndDragDropTarget();
+        return;
+    }
+
+    ImGuiWindow* payload_window = *(ImGuiWindow**)payload->Data;
+    if (AcceptDragDropPayload(IMGUI_PAYLOAD_TYPE_WINDOW, ImGuiDragDropFlags_AcceptBeforeDelivery | ImGuiDragDropFlags_AcceptNoDrawDefaultRect))
+    {
+        // Select target node
+        // (Important: we cannot use g.HoveredDockNode here! Because each of our target node have filters based on payload, each candidate drop target will do its own evaluation)
+        bool dock_into_floating_window = false;
+        ImGuiDockNode* node = NULL;
+        if (window->DockNodeAsHost)
+        {
+            // Cannot assume that node will != NULL even though we passed the rectangle test: it depends on padding/spacing handled by DockNodeTreeFindVisibleNodeByPos().
+            node = DockNodeTreeFindVisibleNodeByPos(window->DockNodeAsHost, g.IO.MousePos);
+
+            // There is an edge case when docking into a dockspace which only has _inactive_ nodes (because none of the windows are active)
+            // In this case we need to fallback into any leaf mode, possibly the central node.
+            // FIXME-20181220: We should not have to test for IsLeafNode() here but we have another bug to fix first.
+            if (node && node->IsDockSpace() && node->IsRootNode())
+                node = (node->CentralNode && node->IsLeafNode()) ? node->CentralNode : DockNodeTreeFindFallbackLeafNode(node);
+        }
+        else
+        {
+            if (window->DockNode)
+                node = window->DockNode;
+            else
+                dock_into_floating_window = true; // Dock into a regular window
+        }
+
+        const ImRect explicit_target_rect = (node && node->TabBar && !node->IsHiddenTabBar() && !node->IsNoTabBar()) ? node->TabBar->BarRect : ImRect(window->Pos, window->Pos + ImVec2(window->Size.x, GetFrameHeight()));
+        const bool is_explicit_target = g.IO.ConfigDockingWithShift || IsMouseHoveringRect(explicit_target_rect.Min, explicit_target_rect.Max);
+
+        // Preview docking request and find out split direction/ratio
+        //const bool do_preview = true;     // Ignore testing for payload->IsPreview() which removes one frame of delay, but breaks overlapping drop targets within the same window.
+        const bool do_preview = payload->IsPreview() || payload->IsDelivery();
+        if (do_preview && (node != NULL || dock_into_floating_window))
+        {
+            // If we have a non-leaf node it means we are hovering the border of a parent node, in which case only outer markers will appear.
+            ImGuiDockPreviewData split_inner;
+            ImGuiDockPreviewData split_outer;
+            ImGuiDockPreviewData* split_data = &split_inner;
+            if (node && (node->ParentNode || node->IsCentralNode() || !node->IsLeafNode()))
+                if (ImGuiDockNode* root_node = DockNodeGetRootNode(node))
+                {
+                    DockNodePreviewDockSetup(window, root_node, payload_window, NULL, &split_outer, is_explicit_target, true);
+                    if (split_outer.IsSplitDirExplicit)
+                        split_data = &split_outer;
+                }
+            if (!node || node->IsLeafNode())
+                DockNodePreviewDockSetup(window, node, payload_window, NULL, &split_inner, is_explicit_target, false);
+            if (split_data == &split_outer)
+                split_inner.IsDropAllowed = false;
+
+            // Draw inner then outer, so that previewed tab (in inner data) will be behind the outer drop boxes
+            DockNodePreviewDockRender(window, node, payload_window, &split_inner);
+            DockNodePreviewDockRender(window, node, payload_window, &split_outer);
+
+            // Queue docking request
+            if (split_data->IsDropAllowed && payload->IsDelivery())
+                DockContextQueueDock(&g, window, split_data->SplitNode, payload_window, split_data->SplitDir, split_data->SplitRatio, split_data == &split_outer);
+        }
+    }
+    EndDragDropTarget();
+}
+
+//-----------------------------------------------------------------------------
+// Docking: Settings
+//-----------------------------------------------------------------------------
+// - DockSettingsRenameNodeReferences()
+// - DockSettingsRemoveNodeReferences()
+// - DockSettingsFindNodeSettings()
+// - DockSettingsHandler_ApplyAll()
+// - DockSettingsHandler_ReadOpen()
+// - DockSettingsHandler_ReadLine()
+// - DockSettingsHandler_DockNodeToSettings()
+// - DockSettingsHandler_WriteAll()
+//-----------------------------------------------------------------------------
+
+static void ImGui::DockSettingsRenameNodeReferences(ImGuiID old_node_id, ImGuiID new_node_id)
+{
+    ImGuiContext& g = *GImGui;
+    IMGUI_DEBUG_LOG_DOCKING("[docking] DockSettingsRenameNodeReferences: from 0x%08X -> to 0x%08X\n", old_node_id, new_node_id);
+    for (int window_n = 0; window_n < g.Windows.Size; window_n++)
+    {
+        ImGuiWindow* window = g.Windows[window_n];
+        if (window->DockId == old_node_id && window->DockNode == NULL)
+            window->DockId = new_node_id;
+    }
+    //// FIXME-OPT: We could remove this loop by storing the index in the map
+    for (ImGuiWindowSettings* settings = g.SettingsWindows.begin(); settings != NULL; settings = g.SettingsWindows.next_chunk(settings))
+        if (settings->DockId == old_node_id)
+            settings->DockId = new_node_id;
+}
+
+// Remove references stored in ImGuiWindowSettings to the given ImGuiDockNodeSettings
+static void ImGui::DockSettingsRemoveNodeReferences(ImGuiID* node_ids, int node_ids_count)
+{
+    ImGuiContext& g = *GImGui;
+    int found = 0;
+    //// FIXME-OPT: We could remove this loop by storing the index in the map
+    for (ImGuiWindowSettings* settings = g.SettingsWindows.begin(); settings != NULL; settings = g.SettingsWindows.next_chunk(settings))
+        for (int node_n = 0; node_n < node_ids_count; node_n++)
+            if (settings->DockId == node_ids[node_n])
+            {
+                settings->DockId = 0;
+                settings->DockOrder = -1;
+                if (++found < node_ids_count)
+                    break;
+                return;
+            }
+}
+
+static ImGuiDockNodeSettings* ImGui::DockSettingsFindNodeSettings(ImGuiContext* ctx, ImGuiID id)
+{
+    // FIXME-OPT
+    ImGuiDockContext* dc = &ctx->DockContext;
+    for (int n = 0; n < dc->NodesSettings.Size; n++)
+        if (dc->NodesSettings[n].ID == id)
+            return &dc->NodesSettings[n];
+    return NULL;
+}
+
+// Clear settings data
+static void ImGui::DockSettingsHandler_ClearAll(ImGuiContext* ctx, ImGuiSettingsHandler*)
+{
+    ImGuiDockContext* dc = &ctx->DockContext;
+    dc->NodesSettings.clear();
+    DockContextClearNodes(ctx, 0, true);
+}
+
+// Recreate nodes based on settings data
+static void ImGui::DockSettingsHandler_ApplyAll(ImGuiContext* ctx, ImGuiSettingsHandler*)
+{
+    // Prune settings at boot time only
+    ImGuiDockContext* dc = &ctx->DockContext;
+    if (ctx->Windows.Size == 0)
+        DockContextPruneUnusedSettingsNodes(ctx);
+    DockContextBuildNodesFromSettings(ctx, dc->NodesSettings.Data, dc->NodesSettings.Size);
+    DockContextBuildAddWindowsToNodes(ctx, 0);
+}
+
+static void* ImGui::DockSettingsHandler_ReadOpen(ImGuiContext*, ImGuiSettingsHandler*, const char* name)
+{
+    if (strcmp(name, "Data") != 0)
+        return NULL;
+    return (void*)1;
+}
+
+static void ImGui::DockSettingsHandler_ReadLine(ImGuiContext* ctx, ImGuiSettingsHandler*, void*, const char* line)
+{
+    char c = 0;
+    int x = 0, y = 0;
+    int r = 0;
+
+    // Parsing, e.g.
+    // " DockNode   ID=0x00000001 Pos=383,193 Size=201,322 Split=Y,0.506 "
+    // "   DockNode ID=0x00000002 Parent=0x00000001 "
+    // Important: this code expect currently fields in a fixed order.
+    ImGuiDockNodeSettings node;
+    line = ImStrSkipBlank(line);
+    if      (strncmp(line, "DockNode", 8) == 0)  { line = ImStrSkipBlank(line + strlen("DockNode")); }
+    else if (strncmp(line, "DockSpace", 9) == 0) { line = ImStrSkipBlank(line + strlen("DockSpace")); node.Flags |= ImGuiDockNodeFlags_DockSpace; }
+    else return;
+    if (sscanf(line, "ID=0x%08X%n",      &node.ID, &r) == 1)            { line += r; } else return;
+    if (sscanf(line, " Parent=0x%08X%n", &node.ParentNodeId, &r) == 1)  { line += r; if (node.ParentNodeId == 0) return; }
+    if (sscanf(line, " Window=0x%08X%n", &node.ParentWindowId, &r) ==1) { line += r; if (node.ParentWindowId == 0) return; }
+    if (node.ParentNodeId == 0)
+    {
+        if (sscanf(line, " Pos=%i,%i%n",  &x, &y, &r) == 2)         { line += r; node.Pos = ImVec2ih((short)x, (short)y); } else return;
+        if (sscanf(line, " Size=%i,%i%n", &x, &y, &r) == 2)         { line += r; node.Size = ImVec2ih((short)x, (short)y); } else return;
+    }
+    else
+    {
+        if (sscanf(line, " SizeRef=%i,%i%n", &x, &y, &r) == 2)      { line += r; node.SizeRef = ImVec2ih((short)x, (short)y); }
+    }
+    if (sscanf(line, " Split=%c%n", &c, &r) == 1)                   { line += r; if (c == 'X') node.SplitAxis = ImGuiAxis_X; else if (c == 'Y') node.SplitAxis = ImGuiAxis_Y; }
+    if (sscanf(line, " NoResize=%d%n", &x, &r) == 1)                { line += r; if (x != 0) node.Flags |= ImGuiDockNodeFlags_NoResize; }
+    if (sscanf(line, " CentralNode=%d%n", &x, &r) == 1)             { line += r; if (x != 0) node.Flags |= ImGuiDockNodeFlags_CentralNode; }
+    if (sscanf(line, " NoTabBar=%d%n", &x, &r) == 1)                { line += r; if (x != 0) node.Flags |= ImGuiDockNodeFlags_NoTabBar; }
+    if (sscanf(line, " HiddenTabBar=%d%n", &x, &r) == 1)            { line += r; if (x != 0) node.Flags |= ImGuiDockNodeFlags_HiddenTabBar; }
+    if (sscanf(line, " NoWindowMenuButton=%d%n", &x, &r) == 1)      { line += r; if (x != 0) node.Flags |= ImGuiDockNodeFlags_NoWindowMenuButton; }
+    if (sscanf(line, " NoCloseButton=%d%n", &x, &r) == 1)           { line += r; if (x != 0) node.Flags |= ImGuiDockNodeFlags_NoCloseButton; }
+    if (sscanf(line, " Selected=0x%08X%n", &node.SelectedTabId,&r) == 1) { line += r; }
+    if (node.ParentNodeId != 0)
+        if (ImGuiDockNodeSettings* parent_settings = DockSettingsFindNodeSettings(ctx, node.ParentNodeId))
+            node.Depth = parent_settings->Depth + 1;
+    ctx->DockContext.NodesSettings.push_back(node);
+}
+
+static void DockSettingsHandler_DockNodeToSettings(ImGuiDockContext* dc, ImGuiDockNode* node, int depth)
+{
+    ImGuiDockNodeSettings node_settings;
+    IM_ASSERT(depth < (1 << (sizeof(node_settings.Depth) << 3)));
+    node_settings.ID = node->ID;
+    node_settings.ParentNodeId = node->ParentNode ? node->ParentNode->ID : 0;
+    node_settings.ParentWindowId = (node->IsDockSpace() && node->HostWindow && node->HostWindow->ParentWindow) ? node->HostWindow->ParentWindow->ID : 0;
+    node_settings.SelectedTabId = node->SelectedTabId;
+    node_settings.SplitAxis = (signed char)(node->IsSplitNode() ? node->SplitAxis : ImGuiAxis_None);
+    node_settings.Depth = (char)depth;
+    node_settings.Flags = (node->LocalFlags & ImGuiDockNodeFlags_SavedFlagsMask_);
+    node_settings.Pos = ImVec2ih(node->Pos);
+    node_settings.Size = ImVec2ih(node->Size);
+    node_settings.SizeRef = ImVec2ih(node->SizeRef);
+    dc->NodesSettings.push_back(node_settings);
+    if (node->ChildNodes[0])
+        DockSettingsHandler_DockNodeToSettings(dc, node->ChildNodes[0], depth + 1);
+    if (node->ChildNodes[1])
+        DockSettingsHandler_DockNodeToSettings(dc, node->ChildNodes[1], depth + 1);
+}
+
+static void ImGui::DockSettingsHandler_WriteAll(ImGuiContext* ctx, ImGuiSettingsHandler* handler, ImGuiTextBuffer* buf)
+{
+    ImGuiContext& g = *ctx;
+    ImGuiDockContext* dc = &ctx->DockContext;
+    if (!(g.IO.ConfigFlags & ImGuiConfigFlags_DockingEnable))
+        return;
+
+    // Gather settings data
+    // (unlike our windows settings, because nodes are always built we can do a full rewrite of the SettingsNode buffer)
+    dc->NodesSettings.resize(0);
+    dc->NodesSettings.reserve(dc->Nodes.Data.Size);
+    for (int n = 0; n < dc->Nodes.Data.Size; n++)
+        if (ImGuiDockNode* node = (ImGuiDockNode*)dc->Nodes.Data[n].val_p)
+            if (node->IsRootNode())
+                DockSettingsHandler_DockNodeToSettings(dc, node, 0);
+
+    int max_depth = 0;
+    for (int node_n = 0; node_n < dc->NodesSettings.Size; node_n++)
+        max_depth = ImMax((int)dc->NodesSettings[node_n].Depth, max_depth);
+
+    // Write to text buffer
+    buf->appendf("[%s][Data]\n", handler->TypeName);
+    for (int node_n = 0; node_n < dc->NodesSettings.Size; node_n++)
+    {
+        const int line_start_pos = buf->size(); (void)line_start_pos;
+        const ImGuiDockNodeSettings* node_settings = &dc->NodesSettings[node_n];
+        buf->appendf("%*s%s%*s", node_settings->Depth * 2, "", (node_settings->Flags & ImGuiDockNodeFlags_DockSpace) ? "DockSpace" : "DockNode ", (max_depth - node_settings->Depth) * 2, "");  // Text align nodes to facilitate looking at .ini file
+        buf->appendf(" ID=0x%08X", node_settings->ID);
+        if (node_settings->ParentNodeId)
+        {
+            buf->appendf(" Parent=0x%08X SizeRef=%d,%d", node_settings->ParentNodeId, node_settings->SizeRef.x, node_settings->SizeRef.y);
+        }
+        else
+        {
+            if (node_settings->ParentWindowId)
+                buf->appendf(" Window=0x%08X", node_settings->ParentWindowId);
+            buf->appendf(" Pos=%d,%d Size=%d,%d", node_settings->Pos.x, node_settings->Pos.y, node_settings->Size.x, node_settings->Size.y);
+        }
+        if (node_settings->SplitAxis != ImGuiAxis_None)
+            buf->appendf(" Split=%c", (node_settings->SplitAxis == ImGuiAxis_X) ? 'X' : 'Y');
+        if (node_settings->Flags & ImGuiDockNodeFlags_NoResize)
+            buf->appendf(" NoResize=1");
+        if (node_settings->Flags & ImGuiDockNodeFlags_CentralNode)
+            buf->appendf(" CentralNode=1");
+        if (node_settings->Flags & ImGuiDockNodeFlags_NoTabBar)
+            buf->appendf(" NoTabBar=1");
+        if (node_settings->Flags & ImGuiDockNodeFlags_HiddenTabBar)
+            buf->appendf(" HiddenTabBar=1");
+        if (node_settings->Flags & ImGuiDockNodeFlags_NoWindowMenuButton)
+            buf->appendf(" NoWindowMenuButton=1");
+        if (node_settings->Flags & ImGuiDockNodeFlags_NoCloseButton)
+            buf->appendf(" NoCloseButton=1");
+        if (node_settings->SelectedTabId)
+            buf->appendf(" Selected=0x%08X", node_settings->SelectedTabId);
+
+        // [DEBUG] Include comments in the .ini file to ease debugging (this makes saving slower!)
+        if (g.IO.ConfigDebugIniSettings)
+            if (ImGuiDockNode* node = DockContextFindNodeByID(ctx, node_settings->ID))
+            {
+                buf->appendf("%*s", ImMax(2, (line_start_pos + 92) - buf->size()), "");     // Align everything
+                if (node->IsDockSpace() && node->HostWindow && node->HostWindow->ParentWindow)
+                    buf->appendf(" ; in '%s'", node->HostWindow->ParentWindow->Name);
+                // Iterate settings so we can give info about windows that didn't exist during the session.
+                int contains_window = 0;
+                for (ImGuiWindowSettings* settings = g.SettingsWindows.begin(); settings != NULL; settings = g.SettingsWindows.next_chunk(settings))
+                    if (settings->DockId == node_settings->ID)
+                    {
+                        if (contains_window++ == 0)
+                            buf->appendf(" ; contains ");
+                        buf->appendf("'%s' ", settings->GetName());
+                    }
+            }
+
+        buf->appendf("\n");
+    }
+    buf->appendf("\n");
+}
 
 
 //-----------------------------------------------------------------------------
@@ -15948,14 +21693,14 @@
     if (HIMC himc = ::ImmGetContext(hwnd))
     {
         COMPOSITIONFORM composition_form = {};
-        composition_form.ptCurrentPos.x = (LONG)data->InputPos.x;
-        composition_form.ptCurrentPos.y = (LONG)data->InputPos.y;
+        composition_form.ptCurrentPos.x = (LONG)(data->InputPos.x - viewport->Pos.x);
+        composition_form.ptCurrentPos.y = (LONG)(data->InputPos.y - viewport->Pos.y);
         composition_form.dwStyle = CFS_FORCE_POSITION;
         ::ImmSetCompositionWindow(himc, &composition_form);
         CANDIDATEFORM candidate_form = {};
         candidate_form.dwStyle = CFS_CANDIDATEPOS;
-        candidate_form.ptCurrentPos.x = (LONG)data->InputPos.x;
-        candidate_form.ptCurrentPos.y = (LONG)data->InputPos.y;
+        candidate_form.ptCurrentPos.x = (LONG)(data->InputPos.x - viewport->Pos.x);
+        candidate_form.ptCurrentPos.y = (LONG)(data->InputPos.y - viewport->Pos.y);
         ::ImmSetCandidateWindow(himc, &candidate_form);
         ::ImmReleaseContext(hwnd, himc);
     }
@@ -15982,6 +21727,7 @@
 // - DebugNodeTexture() [Internal]
 // - ShowMetricsWindow()
 // - DebugNodeColumns() [Internal]
+// - DebugNodeDockNode() [Internal]
 // - DebugNodeDrawList() [Internal]
 // - DebugNodeDrawCmdShowMeshAndBoundingBox() [Internal]
 // - DebugNodeFont() [Internal]
@@ -16020,12 +21766,14 @@
 
     ImVec2 scale = bb.GetSize() / viewport->Size;
     ImVec2 off = bb.Min - viewport->Pos * scale;
-    float alpha_mul = 1.0f;
+    float alpha_mul = (viewport->Flags & ImGuiViewportFlags_IsMinimized) ? 0.30f : 1.00f;
     window->DrawList->AddRectFilled(bb.Min, bb.Max, GetColorU32(ImGuiCol_Border, alpha_mul * 0.40f));
     for (ImGuiWindow* thumb_window : g.Windows)
     {
         if (!thumb_window->WasActive || (thumb_window->Flags & ImGuiWindowFlags_ChildWindow))
             continue;
+        if (thumb_window->Viewport != viewport)
+            continue;
 
         ImRect thumb_r = thumb_window->Rect();
         ImRect title_r = thumb_window->TitleBarRect();
@@ -16049,10 +21797,19 @@
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
 
+    // Draw monitor and calculate their boundaries
     float SCALE = 1.0f / 8.0f;
-    ImRect bb_full(g.Viewports[0]->Pos, g.Viewports[0]->Pos + g.Viewports[0]->Size);
+    ImRect bb_full(FLT_MAX, FLT_MAX, -FLT_MAX, -FLT_MAX);
+    for (ImGuiPlatformMonitor& monitor : g.PlatformIO.Monitors)
+        bb_full.Add(ImRect(monitor.MainPos, monitor.MainPos + monitor.MainSize));
     ImVec2 p = window->DC.CursorPos;
     ImVec2 off = p - bb_full.Min * SCALE;
+    for (ImGuiPlatformMonitor& monitor : g.PlatformIO.Monitors)
+    {
+        ImRect monitor_draw_bb(off + (monitor.MainPos) * SCALE, off + (monitor.MainPos + monitor.MainSize) * SCALE);
+        window->DrawList->AddRect(monitor_draw_bb.Min, monitor_draw_bb.Max, (g.DebugMetricsConfig.HighlightMonitorIdx == g.PlatformIO.Monitors.index_from_ptr(&monitor)) ? IM_COL32(255, 255, 0, 255) : ImGui::GetColorU32(ImGuiCol_Border), 4.0f);
+        window->DrawList->AddRectFilled(monitor_draw_bb.Min, monitor_draw_bb.Max, ImGui::GetColorU32(ImGuiCol_Border, 0.10f), 4.0f);
+    }
 
     // Draw viewports
     for (ImGuiViewportP* viewport : g.Viewports)
@@ -16063,6 +21820,13 @@
     ImGui::Dummy(bb_full.GetSize() * SCALE);
 }
 
+static int IMGUI_CDECL ViewportComparerByLastFocusedStampCount(const void* lhs, const void* rhs)
+{
+    const ImGuiViewportP* a = *(const ImGuiViewportP* const*)lhs;
+    const ImGuiViewportP* b = *(const ImGuiViewportP* const*)rhs;
+    return b->LastFocusedStampCount - a->LastFocusedStampCount;
+}
+
 // Draw an arbitrary US keyboard layout to visualize translated keys
 void ImGui::DebugRenderKeyboardPreview(ImDrawList* draw_list)
 {
@@ -16611,14 +22375,38 @@
         Checkbox("Show ImDrawCmd mesh when hovering", &cfg->ShowDrawCmdMesh);
         Checkbox("Show ImDrawCmd bounding boxes when hovering", &cfg->ShowDrawCmdBoundingBoxes);
         for (ImGuiViewportP* viewport : g.Viewports)
+        {
+            bool viewport_has_drawlist = false;
             for (ImDrawList* draw_list : viewport->DrawDataP.CmdLists)
+            {
+                if (!viewport_has_drawlist)
+                    Text("Active DrawLists in Viewport #%d, ID: 0x%08X", viewport->Idx, viewport->ID);
+                viewport_has_drawlist = true;
                 DebugNodeDrawList(NULL, viewport, draw_list, "DrawList");
+            }
+        }
         TreePop();
     }
 
     // Viewports
     if (TreeNode("Viewports", "Viewports (%d)", g.Viewports.Size))
     {
+        cfg->HighlightMonitorIdx = -1;
+        bool open = TreeNode("Monitors", "Monitors (%d)", g.PlatformIO.Monitors.Size);
+        SameLine();
+        MetricsHelpMarker("Dear ImGui uses monitor data:\n- to query DPI settings on a per monitor basis\n- to position popup/tooltips so they don't straddle monitors.");
+        if (open)
+        {
+            for (int i = 0; i < g.PlatformIO.Monitors.Size; i++)
+            {
+                DebugNodePlatformMonitor(&g.PlatformIO.Monitors[i], "Monitor", i);
+                if (IsItemHovered())
+                    cfg->HighlightMonitorIdx = i;
+            }
+            DebugNodePlatformMonitor(&g.FallbackMonitor, "Fallback", 0);
+            TreePop();
+        }
+
         SetNextItemOpen(true, ImGuiCond_Once);
         if (TreeNode("Windows Minimap"))
         {
@@ -16627,6 +22415,26 @@
         }
         cfg->HighlightViewportID = 0;
 
+        BulletText("MouseViewport: 0x%08X (UserHovered 0x%08X, LastHovered 0x%08X)", g.MouseViewport ? g.MouseViewport->ID : 0, g.IO.MouseHoveredViewport, g.MouseLastHoveredViewport ? g.MouseLastHoveredViewport->ID : 0);
+        if (TreeNode("Inferred Z order (front-to-back)"))
+        {
+            static ImVector<ImGuiViewportP*> viewports;
+            viewports.resize(g.Viewports.Size);
+            memcpy(viewports.Data, g.Viewports.Data, g.Viewports.size_in_bytes());
+            if (viewports.Size > 1)
+                ImQsort(viewports.Data, viewports.Size, sizeof(ImGuiViewport*), ViewportComparerByLastFocusedStampCount);
+            for (ImGuiViewportP* viewport : viewports)
+            {
+                BulletText("Viewport #%d, ID: 0x%08X, LastFocused = %08d, PlatformFocused = %s, Window: \"%s\"",
+                    viewport->Idx, viewport->ID, viewport->LastFocusedStampCount,
+                    (g.PlatformIO.Platform_GetWindowFocus && viewport->PlatformWindowCreated) ? (g.PlatformIO.Platform_GetWindowFocus(viewport) ? "1" : "0") : "N/A",
+                    viewport->Window ? viewport->Window->Name : "N/A");
+                if (IsItemHovered())
+                    cfg->HighlightViewportID = viewport->ID;
+            }
+            TreePop();
+        }
+
         for (ImGuiViewportP* viewport : g.Viewports)
             DebugNodeViewport(viewport);
         TreePop();
@@ -16705,6 +22513,17 @@
 #ifdef IMGUI_HAS_DOCK
     if (TreeNode("Docking"))
     {
+        static bool root_nodes_only = true;
+        ImGuiDockContext* dc = &g.DockContext;
+        Checkbox("List root nodes", &root_nodes_only);
+        Checkbox("Ctrl shows window dock info", &cfg->ShowDockingNodes);
+        if (SmallButton("Clear nodes")) { DockContextClearNodes(&g, 0, true); }
+        SameLine();
+        if (SmallButton("Rebuild all")) { dc->WantFullRebuild = true; }
+        for (int n = 0; n < dc->Nodes.Data.Size; n++)
+            if (ImGuiDockNode* node = (ImGuiDockNode*)dc->Nodes.Data[n].val_p)
+                if (!root_nodes_only || node->IsRootNode())
+                    DebugNodeDockNode(node, "Node");
         TreePop();
     }
 #endif // #ifdef IMGUI_HAS_DOCK
@@ -16748,6 +22567,29 @@
         }
 
 #ifdef IMGUI_HAS_DOCK
+        if (TreeNode("SettingsDocking", "Settings packed data: Docking"))
+        {
+            ImGuiDockContext* dc = &g.DockContext;
+            Text("In SettingsWindows:");
+            for (ImGuiWindowSettings* settings = g.SettingsWindows.begin(); settings != NULL; settings = g.SettingsWindows.next_chunk(settings))
+                if (settings->DockId != 0)
+                    BulletText("Window '%s' -> DockId %08X DockOrder=%d", settings->GetName(), settings->DockId, settings->DockOrder);
+            Text("In SettingsNodes:");
+            for (int n = 0; n < dc->NodesSettings.Size; n++)
+            {
+                ImGuiDockNodeSettings* settings = &dc->NodesSettings[n];
+                const char* selected_tab_name = NULL;
+                if (settings->SelectedTabId)
+                {
+                    if (ImGuiWindow* window = FindWindowByID(settings->SelectedTabId))
+                        selected_tab_name = window->Name;
+                    else if (ImGuiWindowSettings* window_settings = FindWindowSettingsByID(settings->SelectedTabId))
+                        selected_tab_name = window_settings->GetName();
+                }
+                BulletText("Node %08X, Parent %08X, SelectedTab %08X ('%s')", settings->ID, settings->ParentNodeId, settings->SelectedTabId, selected_tab_name ? selected_tab_name : settings->SelectedTabId ? "N/A" : "");
+            }
+            TreePop();
+        }
 #endif // #ifdef IMGUI_HAS_DOCK
 
         if (TreeNode("SettingsIniData", "Settings unpacked data (.ini): %d bytes", g.SettingsIniData.size()))
@@ -16874,9 +22716,11 @@
         Text("WINDOWING");
         Indent();
         Text("HoveredWindow: '%s'", g.HoveredWindow ? g.HoveredWindow->Name : "NULL");
-        Text("HoveredWindow->Root: '%s'", g.HoveredWindow ? g.HoveredWindow->RootWindow->Name : "NULL");
+        Text("HoveredWindow->Root: '%s'", g.HoveredWindow ? g.HoveredWindow->RootWindowDockTree->Name : "NULL");
         Text("HoveredWindowUnderMovingWindow: '%s'", g.HoveredWindowUnderMovingWindow ? g.HoveredWindowUnderMovingWindow->Name : "NULL");
+        Text("HoveredDockNode: 0x%08X", g.DebugHoveredDockNode ? g.DebugHoveredDockNode->ID : 0);
         Text("MovingWindow: '%s'", g.MovingWindow ? g.MovingWindow->Name : "NULL");
+        Text("MouseViewport: 0x%08X (UserHovered 0x%08X, LastHovered 0x%08X)", g.MouseViewport->ID, g.IO.MouseHoveredViewport, g.MouseLastHoveredViewport ? g.MouseLastHoveredViewport->ID : 0);
         Unindent();
 
         Text("ITEMS");
@@ -16970,8 +22814,21 @@
 
 #ifdef IMGUI_HAS_DOCK
     // Overlay: Display Docking info
-    if (show_docking_nodes && g.IO.KeyCtrl)
+    if (cfg->ShowDockingNodes && g.IO.KeyCtrl && g.DebugHoveredDockNode)
     {
+        char buf[64] = "";
+        char* p = buf;
+        ImGuiDockNode* node = g.DebugHoveredDockNode;
+        ImDrawList* overlay_draw_list = node->HostWindow ? GetForegroundDrawList(node->HostWindow) : GetForegroundDrawList(GetMainViewport());
+        p += ImFormatString(p, buf + IM_COUNTOF(buf) - p, "DockId: %X%s\n", node->ID, node->IsCentralNode() ? " *CentralNode*" : "");
+        p += ImFormatString(p, buf + IM_COUNTOF(buf) - p, "WindowClass: %08X\n", node->WindowClass.ClassId);
+        p += ImFormatString(p, buf + IM_COUNTOF(buf) - p, "Size: (%.0f, %.0f)\n", node->Size.x, node->Size.y);
+        p += ImFormatString(p, buf + IM_COUNTOF(buf) - p, "SizeRef: (%.0f, %.0f)\n", node->SizeRef.x, node->SizeRef.y);
+        int depth = DockNodeGetDepth(node);
+        overlay_draw_list->AddRect(node->Pos + ImVec2(3, 3) * (float)depth, node->Pos + node->Size - ImVec2(3, 3) * (float)depth, IM_COL32(200, 100, 100, 255));
+        ImVec2 pos = node->Pos + ImVec2(3, 3) * (float)depth;
+        overlay_draw_list->AddRectFilled(pos - ImVec2(1, 1), pos + CalcTextSize(buf) + ImVec2(1, 1), IM_COL32(200, 100, 100, 255));
+        overlay_draw_list->AddText(NULL, 0.0f, pos, IM_COL32(255, 255, 255, 255), buf);
     }
 #endif // #ifdef IMGUI_HAS_DOCK
 
@@ -17047,11 +22904,98 @@
     TreePop();
 }
 
+static void DebugNodeDockNodeFlags(ImGuiDockNodeFlags* p_flags, const char* label, bool enabled)
+{
+    using namespace ImGui;
+    PushID(label);
+    PushStyleVar(ImGuiStyleVar_FramePadding, ImVec2(0.0f, 0.0f));
+    Text("%s:", label);
+    if (!enabled)
+        BeginDisabled();
+    CheckboxFlags("NoResize", p_flags, ImGuiDockNodeFlags_NoResize);
+    CheckboxFlags("NoResizeX", p_flags, ImGuiDockNodeFlags_NoResizeX);
+    CheckboxFlags("NoResizeY",p_flags, ImGuiDockNodeFlags_NoResizeY);
+    CheckboxFlags("NoTabBar", p_flags, ImGuiDockNodeFlags_NoTabBar);
+    CheckboxFlags("HiddenTabBar", p_flags, ImGuiDockNodeFlags_HiddenTabBar);
+    CheckboxFlags("NoWindowMenuButton", p_flags, ImGuiDockNodeFlags_NoWindowMenuButton);
+    CheckboxFlags("NoCloseButton", p_flags, ImGuiDockNodeFlags_NoCloseButton);
+    CheckboxFlags("DockedWindowsInFocusRoute", p_flags, ImGuiDockNodeFlags_DockedWindowsInFocusRoute);
+    CheckboxFlags("NoDocking", p_flags, ImGuiDockNodeFlags_NoDocking); // Multiple flags
+    CheckboxFlags("NoDockingSplit", p_flags, ImGuiDockNodeFlags_NoDockingSplit);
+    CheckboxFlags("NoDockingSplitOther", p_flags, ImGuiDockNodeFlags_NoDockingSplitOther);
+    CheckboxFlags("NoDockingOver", p_flags, ImGuiDockNodeFlags_NoDockingOverMe);
+    CheckboxFlags("NoDockingOverOther", p_flags, ImGuiDockNodeFlags_NoDockingOverOther);
+    CheckboxFlags("NoDockingOverEmpty", p_flags, ImGuiDockNodeFlags_NoDockingOverEmpty);
+    CheckboxFlags("NoUndocking", p_flags, ImGuiDockNodeFlags_NoUndocking);
+    if (!enabled)
+        EndDisabled();
+    PopStyleVar();
+    PopID();
+}
+
+// [DEBUG] Display contents of ImDockNode
+void ImGui::DebugNodeDockNode(ImGuiDockNode* node, const char* label)
+{
+    ImGuiContext& g = *GImGui;
+    const bool is_alive = (g.FrameCount - node->LastFrameAlive < 2);    // Submitted with ImGuiDockNodeFlags_KeepAliveOnly
+    const bool is_active = (g.FrameCount - node->LastFrameActive < 2);  // Submitted
+    if (!is_alive) { PushStyleColor(ImGuiCol_Text, GetStyleColorVec4(ImGuiCol_TextDisabled)); }
+    bool open;
+    ImGuiTreeNodeFlags tree_node_flags = node->IsFocused ? ImGuiTreeNodeFlags_Selected : ImGuiTreeNodeFlags_None;
+    if (node->Windows.Size > 0)
+        open = TreeNodeEx((void*)(intptr_t)node->ID, tree_node_flags, "%s 0x%04X%s: %d windows (vis: '%s')", label, node->ID, node->IsVisible ? "" : " (hidden)", node->Windows.Size, node->VisibleWindow ? node->VisibleWindow->Name : "NULL");
+    else
+        open = TreeNodeEx((void*)(intptr_t)node->ID, tree_node_flags, "%s 0x%04X%s: %s (vis: '%s')", label, node->ID, node->IsVisible ? "" : " (hidden)", (node->SplitAxis == ImGuiAxis_X) ? "horizontal split" : (node->SplitAxis == ImGuiAxis_Y) ? "vertical split" : "empty", node->VisibleWindow ? node->VisibleWindow->Name : "NULL");
+    if (!is_alive) { PopStyleColor(); }
+    if (is_active && IsItemHovered())
+        if (ImGuiWindow* window = node->HostWindow ? node->HostWindow : node->VisibleWindow)
+            GetForegroundDrawList(window)->AddRect(node->Pos, node->Pos + node->Size, IM_COL32(255, 255, 0, 255));
+    if (open)
+    {
+        IM_ASSERT(node->ChildNodes[0] == NULL || node->ChildNodes[0]->ParentNode == node);
+        IM_ASSERT(node->ChildNodes[1] == NULL || node->ChildNodes[1]->ParentNode == node);
+        BulletText("Pos (%.0f,%.0f), Size (%.0f, %.0f) Ref (%.0f, %.0f)",
+            node->Pos.x, node->Pos.y, node->Size.x, node->Size.y, node->SizeRef.x, node->SizeRef.y);
+        DebugNodeWindow(node->HostWindow, "HostWindow");
+        DebugNodeWindow(node->VisibleWindow, "VisibleWindow");
+        BulletText("SelectedTabID: 0x%08X, LastFocusedNodeID: 0x%08X", node->SelectedTabId, node->LastFocusedNodeId);
+        BulletText("Misc:%s%s%s%s%s%s%s",
+            node->IsDockSpace() ? " IsDockSpace" : "",
+            node->IsCentralNode() ? " IsCentralNode" : "",
+            is_alive ? " IsAlive" : "", is_active ? " IsActive" : "", node->IsFocused ? " IsFocused" : "",
+            node->WantLockSizeOnce ? " WantLockSizeOnce" : "",
+            node->HasCentralNodeChild ? " HasCentralNodeChild" : "");
+        if (TreeNode("flags", "Flags Merged: 0x%04X, Local: 0x%04X, InWindows: 0x%04X, Shared: 0x%04X", node->MergedFlags, node->LocalFlags, node->LocalFlagsInWindows, node->SharedFlags))
+        {
+            if (BeginTable("flags", 4))
+            {
+                TableNextColumn(); DebugNodeDockNodeFlags(&node->MergedFlags, "MergedFlags", false);
+                TableNextColumn(); DebugNodeDockNodeFlags(&node->LocalFlags, "LocalFlags", true);
+                TableNextColumn(); DebugNodeDockNodeFlags(&node->LocalFlagsInWindows, "LocalFlagsInWindows", false);
+                TableNextColumn(); DebugNodeDockNodeFlags(&node->SharedFlags, "SharedFlags", true);
+                EndTable();
+            }
+            TreePop();
+        }
+        if (node->ParentNode)
+            DebugNodeDockNode(node->ParentNode, "ParentNode");
+        if (node->ChildNodes[0])
+            DebugNodeDockNode(node->ChildNodes[0], "Child[0]");
+        if (node->ChildNodes[1])
+            DebugNodeDockNode(node->ChildNodes[1], "Child[1]");
+        if (node->TabBar)
+            DebugNodeTabBar(node->TabBar, "TabBar");
+        DebugNodeWindowsList(&node->Windows, "Windows");
+
+        TreePop();
+    }
+}
+
 // [DEBUG] Display contents of ImDrawList
+// Note that both 'window' and 'viewport' may be NULL here. Viewport is generally null of destroyed popups which previously owned a viewport.
 void ImGui::DebugNodeDrawList(ImGuiWindow* window, ImGuiViewportP* viewport, const ImDrawList* draw_list, const char* label)
 {
     ImGuiContext& g = *GImGui;
-    IM_UNUSED(viewport); // Used in docking branch
     ImGuiMetricsConfig* cfg = &g.DebugMetricsConfig;
     int cmd_count = draw_list->CmdBuffer.Size;
     if (cmd_count > 0 && draw_list->CmdBuffer.back().ElemCount == 0 && draw_list->CmdBuffer.back().UserCallback == NULL)
@@ -17066,7 +23010,7 @@
         return;
     }
 
-    ImDrawList* fg_draw_list = GetForegroundDrawList(window); // Render additional visuals into the top-most draw list
+    ImDrawList* fg_draw_list = viewport ? GetForegroundDrawList(viewport) : NULL; // Render additional visuals into the top-most draw list
     if (window && IsItemHovered() && fg_draw_list)
         fg_draw_list->AddRect(window->Pos, window->Pos + window->Size, IM_COL32(255, 255, 0, 255));
     if (!node_open)
@@ -17466,25 +23410,47 @@
 {
     ImGuiContext& g = *GImGui;
     SetNextItemOpen(true, ImGuiCond_Once);
-    bool open = TreeNode("viewport0", "Viewport #%d", 0);
+    bool open = TreeNode((void*)(intptr_t)viewport->ID, "Viewport #%d, ID: 0x%08X, Parent: 0x%08X, Window: \"%s\"", viewport->Idx, viewport->ID, viewport->ParentViewportId, viewport->Window ? viewport->Window->Name : "N/A");
     if (IsItemHovered())
         g.DebugMetricsConfig.HighlightViewportID = viewport->ID;
     if (open)
     {
         ImGuiWindowFlags flags = viewport->Flags;
-        BulletText("Main Pos: (%.0f,%.0f), Size: (%.0f,%.0f)\nWorkArea Inset Left: %.0f Top: %.0f, Right: %.0f, Bottom: %.0f",
+        BulletText("Main Pos: (%.0f,%.0f), Size: (%.0f,%.0f)\nFrameBufferScale: (%.2f,%.2f)\nWorkArea Inset Left: %.0f Top: %.0f, Right: %.0f, Bottom: %.0f\nMonitor: %d, DpiScale: %.0f%%",
             viewport->Pos.x, viewport->Pos.y, viewport->Size.x, viewport->Size.y,
-            viewport->WorkInsetMin.x, viewport->WorkInsetMin.y, viewport->WorkInsetMax.x, viewport->WorkInsetMax.y);
-        BulletText("Flags: 0x%04X =%s%s%s", viewport->Flags,
-            (flags & ImGuiViewportFlags_IsPlatformWindow)  ? " IsPlatformWindow"  : "",
+            viewport->FramebufferScale.x, viewport->FramebufferScale.y,
+            viewport->WorkInsetMin.x, viewport->WorkInsetMin.y, viewport->WorkInsetMax.x, viewport->WorkInsetMax.y,
+            viewport->PlatformMonitor, viewport->DpiScale * 100.0f);
+        if (viewport->Idx > 0) { SameLine(); if (SmallButton("Reset Pos")) { viewport->Pos = ImVec2(200, 200); viewport->UpdateWorkRect(); if (viewport->Window) viewport->Window->Pos = viewport->Pos; } }
+        BulletText("Flags: 0x%04X =%s%s%s%s%s%s%s%s%s%s%s%s%s", viewport->Flags,
+            //(flags & ImGuiViewportFlags_IsPlatformWindow) ? " IsPlatformWindow" : "", // Omitting because it is the standard
             (flags & ImGuiViewportFlags_IsPlatformMonitor) ? " IsPlatformMonitor" : "",
-            (flags & ImGuiViewportFlags_OwnedByApp)        ? " OwnedByApp"        : "");
+            (flags & ImGuiViewportFlags_IsMinimized) ? " IsMinimized" : "",
+            (flags & ImGuiViewportFlags_IsFocused) ? " IsFocused" : "",
+            (flags & ImGuiViewportFlags_OwnedByApp) ? " OwnedByApp" : "",
+            (flags & ImGuiViewportFlags_NoDecoration) ? " NoDecoration" : "",
+            (flags & ImGuiViewportFlags_NoTaskBarIcon) ? " NoTaskBarIcon" : "",
+            (flags & ImGuiViewportFlags_NoFocusOnAppearing) ? " NoFocusOnAppearing" : "",
+            (flags & ImGuiViewportFlags_NoFocusOnClick) ? " NoFocusOnClick" : "",
+            (flags & ImGuiViewportFlags_NoInputs) ? " NoInputs" : "",
+            (flags & ImGuiViewportFlags_NoRendererClear) ? " NoRendererClear" : "",
+            (flags & ImGuiViewportFlags_NoAutoMerge) ? " NoAutoMerge" : "",
+            (flags & ImGuiViewportFlags_TopMost) ? " TopMost" : "",
+            (flags & ImGuiViewportFlags_CanHostOtherWindows) ? " CanHostOtherWindows" : "");
         for (ImDrawList* draw_list : viewport->DrawDataP.CmdLists)
             DebugNodeDrawList(NULL, viewport, draw_list, "DrawList");
         TreePop();
     }
 }
 
+void ImGui::DebugNodePlatformMonitor(ImGuiPlatformMonitor* monitor, const char* label, int idx)
+{
+    BulletText("%s %d: DPI %.0f%%\n MainMin (%.0f,%.0f), MainMax (%.0f,%.0f), MainSize (%.0f,%.0f)\n WorkMin (%.0f,%.0f), WorkMax (%.0f,%.0f), WorkSize (%.0f,%.0f)",
+        label, idx, monitor->DpiScale * 100.0f,
+        monitor->MainPos.x, monitor->MainPos.y, monitor->MainPos.x + monitor->MainSize.x, monitor->MainPos.y + monitor->MainSize.y, monitor->MainSize.x, monitor->MainSize.y,
+        monitor->WorkPos.x, monitor->WorkPos.y, monitor->WorkPos.x + monitor->WorkSize.x, monitor->WorkPos.y + monitor->WorkSize.y, monitor->WorkSize.x, monitor->WorkSize.y);
+}
+
 void ImGui::DebugNodeWindow(ImGuiWindow* window, const char* label)
 {
     if (window == NULL)
@@ -17523,6 +23489,7 @@
             (window->ChildFlags & ImGuiChildFlags_ResizeX) ? "ResizeX " : "",
             (window->ChildFlags & ImGuiChildFlags_ResizeY) ? "ResizeY " : "",
             (window->ChildFlags & ImGuiChildFlags_NavFlattened) ? "NavFlattened " : "");
+    BulletText("WindowClassId: 0x%08X", window->WindowClass.ClassId);
     BulletText("Scroll: (%.2f/%.2f,%.2f/%.2f) Scrollbar:%s%s", window->Scroll.x, window->ScrollMax.x, window->Scroll.y, window->ScrollMax.y, window->ScrollbarX ? "X" : "", window->ScrollbarY ? "Y" : "");
     BulletText("Active: %d/%d, WriteAccessed: %d, BeginOrderWithinContext: %d", window->Active, window->WasActive, window->WriteAccessed, (window->Active || window->WasActive) ? window->BeginOrderWithinContext : -1);
     BulletText("Appearing: %d, Hidden: %d (CanSkip %d Cannot %d), SkipItems: %d", window->Appearing, window->Hidden, window->HiddenFramesCanSkipItems, window->HiddenFramesCannotSkipItems, window->SkipItems);
@@ -17539,7 +23506,15 @@
     for (int layer = 0; layer < ImGuiNavLayer_COUNT; layer++)
         BulletText("NavPreferredScoringPosRel[%d] = (%.1f,%.1f)", layer, (pr[layer].x == FLT_MAX ? -99999.0f : pr[layer].x), (pr[layer].y == FLT_MAX ? -99999.0f : pr[layer].y)); // Display as 99999.0f so it looks neater.
     BulletText("NavLayersActiveMask: %X, NavLastChildNavWindow: %s", window->DC.NavLayersActiveMask, window->NavLastChildNavWindow ? window->NavLastChildNavWindow->Name : "NULL");
+
+    BulletText("Viewport: %d%s, ViewportId: 0x%08X, ViewportPos: (%.1f,%.1f)", window->Viewport ? window->Viewport->Idx : -1, window->ViewportOwned ? " (Owned)" : "", window->ViewportId, window->ViewportPos.x, window->ViewportPos.y);
+    BulletText("ViewportMonitor: %d", window->Viewport ? window->Viewport->PlatformMonitor : -1);
+    BulletText("DockId: 0x%04X, DockOrder: %d, Act: %d, Vis: %d", window->DockId, window->DockOrder, window->DockIsActive, window->DockTabIsVisible);
+    if (window->DockNode || window->DockNodeAsHost)
+        DebugNodeDockNode(window->DockNodeAsHost ? window->DockNodeAsHost : window->DockNode, window->DockNodeAsHost ? "DockNodeAsHost" : "DockNode");
+
     if (window->RootWindow != window)               { DebugNodeWindow(window->RootWindow, "RootWindow"); }
+    if (window->RootWindowDockTree != window->RootWindow) { DebugNodeWindow(window->RootWindowDockTree, "RootWindowDockTree"); }
     if (window->ParentWindow != NULL)               { DebugNodeWindow(window->ParentWindow, "ParentWindow"); }
     if (window->ParentWindowForFocusRoute != NULL)  { DebugNodeWindow(window->ParentWindowForFocusRoute, "ParentWindowForFocusRoute"); }
     if (window->DC.ChildWindows.Size > 0)           { DebugNodeWindowsList(&window->DC.ChildWindows, "ChildWindows"); }
@@ -17689,12 +23664,14 @@
     ShowDebugLogFlag("Errors", ImGuiDebugLogFlags_EventError);
     ShowDebugLogFlag("ActiveId", ImGuiDebugLogFlags_EventActiveId);
     ShowDebugLogFlag("Clipper", ImGuiDebugLogFlags_EventClipper);
+    ShowDebugLogFlag("Docking", ImGuiDebugLogFlags_EventDocking);
     ShowDebugLogFlag("Focus", ImGuiDebugLogFlags_EventFocus);
     ShowDebugLogFlag("IO", ImGuiDebugLogFlags_EventIO);
     ShowDebugLogFlag("Font", ImGuiDebugLogFlags_EventFont);
     ShowDebugLogFlag("Nav", ImGuiDebugLogFlags_EventNav);
     ShowDebugLogFlag("Popup", ImGuiDebugLogFlags_EventPopup);
     ShowDebugLogFlag("Selection", ImGuiDebugLogFlags_EventSelection);
+    ShowDebugLogFlag("Viewport", ImGuiDebugLogFlags_EventViewport);
     ShowDebugLogFlag("InputRouting", ImGuiDebugLogFlags_EventInputRouting);
 
     if (SmallButton("Clear"))

diff --git a/imgui.h b/imgui.h
index e3edac8..e52b124 100644
--- a/imgui.h
+++ b/imgui.h

@@ -33,6 +33,8 @@
 #define IMGUI_VERSION_NUM   19261
 #define IMGUI_HAS_TABLE             // Added BeginTable() - from IMGUI_VERSION_NUM >= 18000
 #define IMGUI_HAS_TEXTURES          // Added ImGuiBackendFlags_RendererHasTextures - from IMGUI_VERSION_NUM >= 19198
+#define IMGUI_HAS_VIEWPORT          // In 'docking' WIP branch.
+#define IMGUI_HAS_DOCK              // In 'docking' WIP branch.
 
 /*
 
@@ -46,14 +48,14 @@
 // [SECTION] Helpers: Debug log, Memory allocations macros, ImVector<>
 // [SECTION] ImGuiStyle
 // [SECTION] ImGuiIO
-// [SECTION] Misc data structures (ImGuiInputTextCallbackData, ImGuiSizeCallbackData, ImGuiPayload)
+// [SECTION] Misc data structures (ImGuiInputTextCallbackData, ImGuiSizeCallbackData, ImGuiWindowClass, ImGuiPayload)
 // [SECTION] Helpers (ImGuiOnceUponAFrame, ImGuiTextFilter, ImGuiTextBuffer, ImGuiStorage, ImGuiListClipper, Math Operators, ImColor)
 // [SECTION] Multi-Select API flags and structures (ImGuiMultiSelectFlags, ImGuiMultiSelectIO, ImGuiSelectionRequest, ImGuiSelectionBasicStorage, ImGuiSelectionExternalStorage)
 // [SECTION] Drawing API (ImDrawCallback, ImDrawCmd, ImDrawIdx, ImDrawVert, ImDrawChannel, ImDrawListSplitter, ImDrawFlags, ImDrawListFlags, ImDrawList, ImDrawData)
 // [SECTION] Texture API (ImTextureFormat, ImTextureStatus, ImTextureRect, ImTextureData)
 // [SECTION] Font API (ImFontConfig, ImFontGlyph, ImFontGlyphRangesBuilder, ImFontAtlasFlags, ImFontAtlas, ImFontBaked, ImFont)
 // [SECTION] Viewports (ImGuiViewportFlags, ImGuiViewport)
-// [SECTION] ImGuiPlatformIO + other Platform Dependent Interfaces (ImGuiPlatformImeData)
+// [SECTION] ImGuiPlatformIO + other Platform Dependent Interfaces (ImGuiPlatformMonitor, ImGuiPlatformImeData)
 // [SECTION] Obsolete functions and types
 
 */
@@ -197,8 +199,9 @@
 struct ImGuiMultiSelectIO;          // Structure to interact with a BeginMultiSelect()/EndMultiSelect() block
 struct ImGuiOnceUponAFrame;         // Helper for running a block of code not more than once a frame
 struct ImGuiPayload;                // User data payload for drag and drop operations
-struct ImGuiPlatformIO;             // Interface between platform/renderer backends and ImGui (e.g. Clipboard, IME hooks). Extends ImGuiIO. In docking branch, this gets extended to support multi-viewports.
+struct ImGuiPlatformIO;             // Interface between platform/renderer backends and ImGui (e.g. Clipboard, IME, Multi-Viewport support). Extends ImGuiIO.
 struct ImGuiPlatformImeData;        // Platform IME data for io.PlatformSetImeDataFn() function.
+struct ImGuiPlatformMonitor;        // Multi-viewport support: user-provided bounds for each connected monitor/display. Used when positioning popups and tooltips to avoid them straddling monitors
 struct ImGuiSelectionBasicStorage;  // Optional helper to store multi-selection state + apply multi-selection requests.
 struct ImGuiSelectionExternalStorage;//Optional helper to apply multi-selection requests to existing randomly accessible storage.
 struct ImGuiSelectionRequest;       // A selection request (stored in ImGuiMultiSelectIO)
@@ -210,7 +213,8 @@
 struct ImGuiTableColumnSortSpecs;   // Sorting specification for one column of a table
 struct ImGuiTextBuffer;             // Helper to hold and append into a text buffer (~string builder)
 struct ImGuiTextFilter;             // Helper to parse and apply text filters (e.g. "aaaaa[,bbbbb][,ccccc]")
-struct ImGuiViewport;               // A Platform Window (always only one in 'master' branch), in the future may represent Platform Monitor
+struct ImGuiViewport;               // A Platform Window (always 1 unless multi-viewport are enabled. One per platform window to output to). In the future may represent Platform Monitor
+struct ImGuiWindowClass;            // Window class (rare/advanced uses: provide hints to the platform backend via altered viewport flags and parent/child info)
 
 // Enumerations
 // - We don't use strongly typed enums much because they add constraints (can't extend in private code, can't store typed in bit fields, extra casting on iteration)
@@ -246,6 +250,7 @@
 typedef int ImGuiColorEditFlags;    // -> enum ImGuiColorEditFlags_  // Flags: for ColorEdit4(), ColorPicker4() etc.
 typedef int ImGuiConfigFlags;       // -> enum ImGuiConfigFlags_     // Flags: for io.ConfigFlags
 typedef int ImGuiComboFlags;        // -> enum ImGuiComboFlags_      // Flags: for BeginCombo()
+typedef int ImGuiDockNodeFlags;     // -> enum ImGuiDockNodeFlags_   // Flags: for DockSpace()
 typedef int ImGuiDragDropFlags;     // -> enum ImGuiDragDropFlags_   // Flags: for BeginDragDropSource(), AcceptDragDropPayload()
 typedef int ImGuiFocusedFlags;      // -> enum ImGuiFocusedFlags_    // Flags: for IsWindowFocused()
 typedef int ImGuiHoveredFlags;      // -> enum ImGuiHoveredFlags_    // Flags: for IsItemHovered(), IsWindowHovered() etc.
@@ -464,10 +469,12 @@
     IMGUI_API bool          IsWindowFocused(ImGuiFocusedFlags flags=0); // is current window focused? or its root/child, depending on flags. see flags for options.
     IMGUI_API bool          IsWindowHovered(ImGuiHoveredFlags flags=0); // is current window hovered and hoverable (e.g. not blocked by a popup/modal)? See ImGuiHoveredFlags_ for options. IMPORTANT: If you are trying to check whether your mouse should be dispatched to Dear ImGui or to your underlying app, you should not use this function! Use the 'io.WantCaptureMouse' boolean for that! Refer to FAQ entry "How can I tell whether to dispatch mouse/keyboard to Dear ImGui or my application?" for details.
     IMGUI_API ImDrawList*   GetWindowDrawList();                        // get draw list associated to the current window, to append your own drawing primitives
+    IMGUI_API float         GetWindowDpiScale();                        // get DPI scale currently associated to the current window's viewport.
     IMGUI_API ImVec2        GetWindowPos();                             // get current window position in screen space (IT IS UNLIKELY YOU EVER NEED TO USE THIS. Consider always using GetCursorScreenPos() and GetContentRegionAvail() instead)
     IMGUI_API ImVec2        GetWindowSize();                            // get current window size (IT IS UNLIKELY YOU EVER NEED TO USE THIS. Consider always using GetCursorScreenPos() and GetContentRegionAvail() instead)
     IMGUI_API float         GetWindowWidth();                           // get current window width (IT IS UNLIKELY YOU EVER NEED TO USE THIS). Shortcut for GetWindowSize().x.
     IMGUI_API float         GetWindowHeight();                          // get current window height (IT IS UNLIKELY YOU EVER NEED TO USE THIS). Shortcut for GetWindowSize().y.
+    IMGUI_API ImGuiViewport*GetWindowViewport();                        // get viewport currently associated to the current window.
 
     // Window manipulation
     // - Prefer using SetNextXXX functions (before Begin) rather that SetXXX functions (after Begin).
@@ -479,6 +486,7 @@
     IMGUI_API void          SetNextWindowFocus();                                                       // set next window to be focused / top-most. call before Begin()
     IMGUI_API void          SetNextWindowScroll(const ImVec2& scroll);                                  // set next window scrolling value (use < 0.0f to not affect a given axis).
     IMGUI_API void          SetNextWindowBgAlpha(float alpha);                                          // set next window background color alpha. helper to easily override the Alpha component of ImGuiCol_WindowBg/ChildBg/PopupBg. you may also use ImGuiWindowFlags_NoBackground.
+    IMGUI_API void          SetNextWindowViewport(ImGuiID viewport_id);                                 // set next window viewport
     IMGUI_API void          SetWindowPos(const ImVec2& pos, ImGuiCond cond = 0);                        // (not recommended) set current window position - call within Begin()/End(). prefer using SetNextWindowPos(), as this may incur tearing and side-effects.
     IMGUI_API void          SetWindowSize(const ImVec2& size, ImGuiCond cond = 0);                      // (not recommended) set current window size - call within Begin()/End(). set to ImVec2(0, 0) to force an auto-fit. prefer using SetNextWindowSize(), as this may incur tearing and minor side-effects.
     IMGUI_API void          SetWindowCollapsed(bool collapsed, ImGuiCond cond = 0);                     // (not recommended) set current window collapsed state. prefer using SetNextWindowCollapsed().
@@ -954,6 +962,34 @@
     IMGUI_API bool          TabItemButton(const char* label, ImGuiTabItemFlags flags = 0);      // create a Tab behaving like a button. return true when clicked. cannot be selected in the tab bar.
     IMGUI_API void          SetTabItemClosed(const char* tab_or_docked_window_label);           // notify TabBar or Docking system of a closed tab/window ahead (useful to reduce visual flicker on reorderable tab bars). For tab-bar: call after BeginTabBar() and before Tab submissions. Otherwise call with a window name.
 
+    // Docking
+    // - Read https://github.com/ocornut/imgui/wiki/Docking for details.
+    // - Enable with io.ConfigFlags |= ImGuiConfigFlags_DockingEnable.
+    // - You can use many Docking facilities without calling any API.
+    //   - Drag from window title bar or their tab to dock/undock. Hold SHIFT to disable docking.
+    //   - Drag from window menu button (upper-left button) to undock an entire node (all windows).
+    //   - When io.ConfigDockingWithShift == true, you instead need to hold SHIFT to enable docking.
+    // - DockSpaceOverViewport:
+    //   - This is a helper to create an invisible window covering a viewport, then submit a DockSpace() into it.
+    //   - Most applications can simply call DockSpaceOverViewport() once to allow docking windows into e.g. the edge of your screen.
+    //     e.g. ImGui::NewFrame(); ImGui::DockSpaceOverViewport();                                                   // Create a dockspace in main viewport.
+    //      or: ImGui::NewFrame(); ImGui::DockSpaceOverViewport(0, nullptr, ImGuiDockNodeFlags_PassthruCentralNode); // Create a dockspace in main viewport, central node is transparent.
+    // - Dockspaces:
+    //   - A dockspace is an explicit dock node within an existing window.
+    //   - IMPORTANT: Dockspaces need to be submitted _before_ any window they can host. Submit them early in your frame!
+    //   - IMPORTANT: Dockspaces need to be kept alive if hidden, otherwise windows docked into it will be undocked.
+    //     If you have e.g. multiple tabs with a dockspace inside each tab: submit the non-visible dockspaces with ImGuiDockNodeFlags_KeepAliveOnly.
+    //   - See 'Demo->Examples->Dockspace' or 'Demo->Examples->Documents' for more detailed demos.
+    // - Programmatic docking:
+    //   - There is no public API yet other than the very limited SetNextWindowDockID() function. Sorry for that!
+    //   - Read https://github.com/ocornut/imgui/wiki/Docking for examples of how to use current internal API.
+    IMGUI_API ImGuiID       DockSpace(ImGuiID dockspace_id, const ImVec2& size = ImVec2(0, 0), ImGuiDockNodeFlags flags = 0, const ImGuiWindowClass* window_class = NULL);
+    IMGUI_API ImGuiID       DockSpaceOverViewport(ImGuiID dockspace_id = 0, const ImGuiViewport* viewport = NULL, ImGuiDockNodeFlags flags = 0, const ImGuiWindowClass* window_class = NULL);
+    IMGUI_API void          SetNextWindowDockID(ImGuiID dock_id, ImGuiCond cond = 0);           // set next window dock id
+    IMGUI_API void          SetNextWindowClass(const ImGuiWindowClass* window_class);           // set next window class (control docking compatibility + provide hints to platform backend via custom viewport flags and platform parent/child relationship)
+    IMGUI_API ImGuiID       GetWindowDockID();                                                  // get dock id of current window, or 0 if not associated to any docking node.
+    IMGUI_API bool          IsWindowDocked();                                                   // is current window docked into another window?
+
     // Logging/Capture
     // - All text output from the interface can be captured into tty/file/clipboard. By default, tree nodes are automatically opened during logging.
     IMGUI_API void          LogToTTY(int auto_open_depth = -1);                                 // start logging to tty (stdout)
@@ -1029,8 +1065,8 @@
     IMGUI_API ImGuiViewport* GetMainViewport();                                                 // return primary/default viewport. This can never be NULL.
 
     // Background/Foreground Draw Lists
-    IMGUI_API ImDrawList*   GetBackgroundDrawList();                                            // this draw list will be the first rendered one. Useful to quickly draw shapes/text behind dear imgui contents.
-    IMGUI_API ImDrawList*   GetForegroundDrawList();                                            // this draw list will be the last rendered one. Useful to quickly draw shapes/text over dear imgui contents.
+    IMGUI_API ImDrawList*   GetBackgroundDrawList(ImGuiViewport* viewport = NULL);              // get background draw list for the given viewport or viewport associated to the current window. this draw list will be the first rendering one. Useful to quickly draw shapes/text behind dear imgui contents.
+    IMGUI_API ImDrawList*   GetForegroundDrawList(ImGuiViewport* viewport = NULL);              // get foreground draw list for the given viewport or viewport associated to the current window. this draw list will be the top-most rendered one. Useful to quickly draw shapes/text over dear imgui contents.
 
     // Miscellaneous Utilities
     IMGUI_API bool          IsRectVisible(const ImVec2& size);                                  // test if rectangle (of given size, starting from cursor position) is visible / not clipped.
@@ -1152,6 +1188,15 @@
     IMGUI_API void*         MemAlloc(size_t size);
     IMGUI_API void          MemFree(void* ptr);
 
+    // (Optional) Platform/OS interface for multi-viewport support
+    // Read comments around the ImGuiPlatformIO structure for more details.
+    // Note: You may use GetWindowViewport() to get the current viewport of the current window.
+    IMGUI_API void          UpdatePlatformWindows();                                // call in main loop. will call CreateWindow/ResizeWindow/etc. platform functions for each secondary viewport, and DestroyWindow for each inactive viewport.
+    IMGUI_API void          RenderPlatformWindowsDefault(void* platform_render_arg = NULL, void* renderer_render_arg = NULL); // call in main loop. will call RenderWindow/SwapBuffers platform functions for each secondary viewport which doesn't have the ImGuiViewportFlags_Minimized flag set. May be reimplemented by user for custom rendering needs.
+    IMGUI_API void          DestroyPlatformWindows();                               // call DestroyWindow platform functions for all viewports. call from backend Shutdown() if you need to close platform windows before imgui shutdown. otherwise will be called by DestroyContext().
+    IMGUI_API ImGuiViewport* FindViewportByID(ImGuiID viewport_id);                 // this is a helper for backends.
+    IMGUI_API ImGuiViewport* FindViewportByPlatformHandle(void* platform_handle);   // this is a helper for backends. the type platform_handle is decided by the backend (e.g. HWND, MyWindow*, GLFWwindow* etc.)
+
 } // namespace ImGui
 
 //-----------------------------------------------------------------------------
@@ -1182,11 +1227,13 @@
     ImGuiWindowFlags_NoNavInputs            = 1 << 16,  // No keyboard/gamepad navigation within the window
     ImGuiWindowFlags_NoNavFocus             = 1 << 17,  // No focusing toward this window with keyboard/gamepad navigation (e.g. skipped by Ctrl+Tab)
     ImGuiWindowFlags_UnsavedDocument        = 1 << 18,  // Display a dot next to the title. When used in a tab/docking context, tab is selected when clicking the X + closure is not assumed (will wait for user to stop submitting the tab). Otherwise closure is assumed when pressing the X, so if you keep submitting the tab may reappear at end of tab bar.
+    ImGuiWindowFlags_NoDocking              = 1 << 19,  // Disable docking of this window
     ImGuiWindowFlags_NoNav                  = ImGuiWindowFlags_NoNavInputs | ImGuiWindowFlags_NoNavFocus,
     ImGuiWindowFlags_NoDecoration           = ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoScrollbar | ImGuiWindowFlags_NoCollapse,
     ImGuiWindowFlags_NoInputs               = ImGuiWindowFlags_NoMouseInputs | ImGuiWindowFlags_NoNavInputs | ImGuiWindowFlags_NoNavFocus,
 
     // [Internal]
+    ImGuiWindowFlags_DockNodeHost           = 1 << 23,  // Don't use! For internal use by Begin()/NewFrame()
     ImGuiWindowFlags_ChildWindow            = 1 << 24,  // Don't use! For internal use by BeginChild()
     ImGuiWindowFlags_Tooltip                = 1 << 25,  // Don't use! For internal use by BeginTooltip()
     ImGuiWindowFlags_Popup                  = 1 << 26,  // Don't use! For internal use by BeginPopup()
@@ -1432,7 +1479,7 @@
     ImGuiFocusedFlags_RootWindow                    = 1 << 1,   // Test from root window (top most parent of the current hierarchy)
     ImGuiFocusedFlags_AnyWindow                     = 1 << 2,   // Return true if any window is focused. Important: If you are trying to tell how to dispatch your low-level inputs, do NOT use this. Use 'io.WantCaptureMouse' instead! Please read the FAQ!
     ImGuiFocusedFlags_NoPopupHierarchy              = 1 << 3,   // Do not consider popup hierarchy (do not treat popup emitter as parent of popup) (when used with _ChildWindows or _RootWindow)
-    //ImGuiFocusedFlags_DockHierarchy               = 1 << 4,   // Consider docking hierarchy (treat dockspace host as parent of docked window) (when used with _ChildWindows or _RootWindow)
+    ImGuiFocusedFlags_DockHierarchy                 = 1 << 4,   // Consider docking hierarchy (treat dockspace host as parent of docked window) (when used with _ChildWindows or _RootWindow)
     ImGuiFocusedFlags_RootAndChildWindows           = ImGuiFocusedFlags_RootWindow | ImGuiFocusedFlags_ChildWindows,
 };
 
@@ -1446,7 +1493,7 @@
     ImGuiHoveredFlags_RootWindow                    = 1 << 1,   // IsWindowHovered() only: Test from root window (top most parent of the current hierarchy)
     ImGuiHoveredFlags_AnyWindow                     = 1 << 2,   // IsWindowHovered() only: Return true if any window is hovered
     ImGuiHoveredFlags_NoPopupHierarchy              = 1 << 3,   // IsWindowHovered() only: Do not consider popup hierarchy (do not treat popup emitter as parent of popup) (when used with _ChildWindows or _RootWindow)
-    //ImGuiHoveredFlags_DockHierarchy               = 1 << 4,   // IsWindowHovered() only: Consider docking hierarchy (treat dockspace host as parent of docked window) (when used with _ChildWindows or _RootWindow)
+    ImGuiHoveredFlags_DockHierarchy                 = 1 << 4,   // IsWindowHovered() only: Consider docking hierarchy (treat dockspace host as parent of docked window) (when used with _ChildWindows or _RootWindow)
     ImGuiHoveredFlags_AllowWhenBlockedByPopup       = 1 << 5,   // Return true even if a popup window is normally blocking access to this item/window
     //ImGuiHoveredFlags_AllowWhenBlockedByModal     = 1 << 6,   // Return true even if a modal popup window is normally blocking access to this item/window. FIXME-TODO: Unavailable yet.
     ImGuiHoveredFlags_AllowWhenBlockedByActiveItem  = 1 << 7,   // Return true even if an active item is blocking access to this item/window. Useful for Drag and Drop patterns.
@@ -1476,6 +1523,27 @@
     ImGuiHoveredFlags_NoSharedDelay                 = 1 << 17,  // IsItemHovered() only: Disable shared delay system where moving from one item to the next keeps the previous timer for a short time (standard for tooltips with long delays)
 };
 
+// Flags for ImGui::DockSpace(), shared/inherited by child nodes.
+// (Some flags can be applied to individual nodes directly)
+// FIXME-DOCK: Also see ImGuiDockNodeFlagsPrivate_ which may involve using the WIP and internal DockBuilder api.
+enum ImGuiDockNodeFlags_
+{
+    ImGuiDockNodeFlags_None                         = 0,
+    ImGuiDockNodeFlags_KeepAliveOnly                = 1 << 0,   //       // Don't display the dockspace node but keep it alive. Windows docked into this dockspace node won't be undocked.
+    //ImGuiDockNodeFlags_NoCentralNode              = 1 << 1,   //       // Disable Central Node (the node which can stay empty)
+    ImGuiDockNodeFlags_NoDockingOverCentralNode     = 1 << 2,   //       // Disable docking over the Central Node, which will be always kept empty.
+    ImGuiDockNodeFlags_PassthruCentralNode          = 1 << 3,   //       // Enable passthru dockspace: 1) DockSpace() will render a ImGuiCol_WindowBg background covering everything excepted the Central Node when empty. Meaning the host window should probably use SetNextWindowBgAlpha(0.0f) prior to Begin() when using this. 2) When Central Node is empty: let inputs pass-through + won't display a DockingEmptyBg background. See demo for details.
+    ImGuiDockNodeFlags_NoDockingSplit               = 1 << 4,   //       // Disable other windows/nodes from splitting this node.
+    ImGuiDockNodeFlags_NoResize                     = 1 << 5,   // Saved // Disable resizing node using the splitter/separators. Useful with programmatically setup dockspaces.
+    ImGuiDockNodeFlags_AutoHideTabBar               = 1 << 6,   //       // Tab bar will automatically hide when there is a single window in the dock node.
+    ImGuiDockNodeFlags_NoUndocking                  = 1 << 7,   //       // Disable undocking this node.
+
+#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
+    ImGuiDockNodeFlags_NoSplit                      = ImGuiDockNodeFlags_NoDockingSplit, // Renamed in 1.90
+    ImGuiDockNodeFlags_NoDockingInCentralNode       = ImGuiDockNodeFlags_NoDockingOverCentralNode, // Renamed in 1.90
+#endif
+};
+
 // Flags for ImGui::BeginDragDropSource(), ImGui::AcceptDragDropPayload()
 enum ImGuiDragDropFlags_
 {
@@ -1709,6 +1777,13 @@
     ImGuiConfigFlags_NoMouseCursorChange    = 1 << 5,   // Instruct backend to not alter mouse cursor shape and visibility. Use if the backend cursor changes are interfering with yours and you don't want to use SetMouseCursor() to change mouse cursor. You may want to honor requests from imgui by reading GetMouseCursor() yourself instead.
     ImGuiConfigFlags_NoKeyboard             = 1 << 6,   // Instruct dear imgui to disable keyboard inputs and interactions. This is done by ignoring keyboard events and clearing existing states.
 
+    // [BETA] Docking
+    ImGuiConfigFlags_DockingEnable          = 1 << 7,   // Docking enable flags.
+
+    // [BETA] Viewports
+    // When using viewports it is recommended that your default value for ImGuiCol_WindowBg is opaque (Alpha=1.0) so transition to a viewport won't be noticeable.
+    ImGuiConfigFlags_ViewportsEnable        = 1 << 10,  // Viewport enable flags (require both ImGuiBackendFlags_PlatformHasViewports + ImGuiBackendFlags_RendererHasViewports set by the respective backends)
+
     // User storage (to allow your backend/engine to communicate to code that may be shared between multiple projects. Those flags are NOT used by core Dear ImGui)
     ImGuiConfigFlags_IsSRGB                 = 1 << 20,  // Application is SRGB-aware.
     ImGuiConfigFlags_IsTouchScreen          = 1 << 21,  // Application is using a touch screen instead of a mouse.
@@ -1716,6 +1791,8 @@
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
     ImGuiConfigFlags_NavEnableSetMousePos   = 1 << 2,   // [moved/renamed in 1.91.4] -> use bool io.ConfigNavMoveSetMousePos
     ImGuiConfigFlags_NavNoCaptureKeyboard   = 1 << 3,   // [moved/renamed in 1.91.4] -> use bool io.ConfigNavCaptureKeyboard
+    ImGuiConfigFlags_DpiEnableScaleFonts    = 1 << 14,  // [moved/renamed in 1.92.0] -> use bool io.ConfigDpiScaleFonts
+    ImGuiConfigFlags_DpiEnableScaleViewports= 1 << 15,  // [moved/renamed in 1.92.0] -> use bool io.ConfigDpiScaleViewports
 #endif
 };
 
@@ -1728,6 +1805,12 @@
     ImGuiBackendFlags_HasSetMousePos        = 1 << 2,   // Backend Platform supports io.WantSetMousePos requests to reposition the OS mouse position (only used if io.ConfigNavMoveSetMousePos is set).
     ImGuiBackendFlags_RendererHasVtxOffset  = 1 << 3,   // Backend Renderer supports ImDrawCmd::VtxOffset. This enables output of large meshes (64K+ vertices) while still using 16-bit indices.
     ImGuiBackendFlags_RendererHasTextures   = 1 << 4,   // Backend Renderer supports ImTextureData requests to create/update/destroy textures. This enables incremental texture updates and texture reloads. See https://github.com/ocornut/imgui/blob/master/docs/BACKENDS.md for instructions on how to upgrade your custom backend.
+
+    // [BETA] Multi-Viewports
+    ImGuiBackendFlags_RendererHasViewports  = 1 << 10,  // Backend Renderer supports multiple viewports.
+    ImGuiBackendFlags_PlatformHasViewports  = 1 << 11,  // Backend Platform supports multiple viewports.
+    ImGuiBackendFlags_HasMouseHoveredViewport=1 << 12,  // Backend Platform supports calling io.AddMouseViewportEvent() with the viewport under the mouse. IF POSSIBLE, ignore viewports with the ImGuiViewportFlags_NoInputs flag (Win32 backend, GLFW 3.30+ backend can do this, SDL backend cannot). If this cannot be done, Dear ImGui needs to use a flawed heuristic to find the viewport under.
+    ImGuiBackendFlags_HasParentViewport     = 1 << 13,  // Backend Platform supports honoring viewport->ParentViewport/ParentViewportId value, by applying the corresponding parent/child relation at the Platform level.
 };
 
 // Enumeration for PushStyleColor() / PopStyleColor()
@@ -1774,6 +1857,8 @@
     ImGuiCol_TabDimmed,             // Tab background, when tab-bar is unfocused & tab is unselected
     ImGuiCol_TabDimmedSelected,     // Tab background, when tab-bar is unfocused & tab is selected
     ImGuiCol_TabDimmedSelectedOverline,//..horizontal overline, when tab-bar is unfocused & tab is selected
+    ImGuiCol_DockingPreview,        // Preview overlay color when about to docking something
+    ImGuiCol_DockingEmptyBg,        // Background color for empty node (e.g. CentralNode with no window docked into it)
     ImGuiCol_PlotLines,
     ImGuiCol_PlotLinesHovered,
     ImGuiCol_PlotHistogram,
@@ -1854,6 +1939,7 @@
     ImGuiStyleVar_SeparatorTextBorderSize,  // float     SeparatorTextBorderSize
     ImGuiStyleVar_SeparatorTextAlign,       // ImVec2    SeparatorTextAlign
     ImGuiStyleVar_SeparatorTextPadding,     // ImVec2    SeparatorTextPadding
+    ImGuiStyleVar_DockingSeparatorSize,     // float     DockingSeparatorSize
     ImGuiStyleVar_COUNT
 };
 
@@ -2335,6 +2421,8 @@
     ImVec2      SeparatorTextPadding;       // Horizontal offset of text from each edge of the separator + spacing on other axis. Generally small values. .y is recommended to be == FramePadding.y.
     ImVec2      DisplayWindowPadding;       // Apply to regular windows: amount which we enforce to keep visible when moving near edges of your screen.
     ImVec2      DisplaySafeAreaPadding;     // Apply to every windows, menus, popups, tooltips: amount where we avoid displaying contents. Adjust if you cannot see the edges of your screen (e.g. on a TV where scaling has not been configured).
+    bool        DockingNodeHasCloseButton;  // Docking node has their own CloseButton() to close all docked windows.
+    float       DockingSeparatorSize;       // Thickness of resizing border between docked windows
     float       MouseCursorScale;           // Scale software rendered mouse cursor (when io.MouseDrawCursor is enabled). We apply per-monitor DPI scaling over this scale. May be removed later.
     bool        AntiAliasedLines;           // Enable anti-aliased lines/borders. Disable if you are really tight on CPU/GPU. Latched at the beginning of the frame (copied to ImDrawList).
     bool        AntiAliasedLinesUseTex;     // Enable anti-aliased lines/borders using textures where possible. Require backend to render with bilinear filtering (NOT point/nearest filtering). Latched at the beginning of the frame (copied to ImDrawList).
@@ -2419,6 +2507,25 @@
     bool        ConfigNavCursorVisibleAuto;     // = true           // Using directional navigation key makes the cursor visible. Mouse click hides the cursor.
     bool        ConfigNavCursorVisibleAlways;   // = false          // Navigation cursor is always visible.
 
+    // Docking options (when ImGuiConfigFlags_DockingEnable is set)
+    bool        ConfigDockingNoSplit;           // = false          // Simplified docking mode: disable window splitting, so docking is limited to merging multiple windows together into tab-bars.
+    bool        ConfigDockingNoDockingOver;     // = false          // Simplified docking mode: disable window merging into a same tab-bar, so docking is limited to splitting windows.
+    bool        ConfigDockingWithShift;         // = false          // Enable docking with holding Shift key (reduce visual noise, allows dropping in wider space)
+    bool        ConfigDockingAlwaysTabBar;      // = false          // [BETA] [FIXME: This currently creates regression with auto-sizing and general overhead] Make every single floating window display within a docking node.
+    bool        ConfigDockingTransparentPayload;// = false          // [BETA] Make window or viewport transparent when docking and only display docking boxes on the target viewport. Useful if rendering of multiple viewport cannot be synced. Best used with ConfigViewportsNoAutoMerge.
+
+    // Viewport options (when ImGuiConfigFlags_ViewportsEnable is set)
+    bool        ConfigViewportsNoAutoMerge;     // = false;         // Set to make all floating imgui windows always create their own viewport. Otherwise, they are merged into the main host viewports when overlapping it. May also set ImGuiViewportFlags_NoAutoMerge on individual viewport.
+    bool        ConfigViewportsNoTaskBarIcon;   // = false          // Disable default OS task bar icon flag for secondary viewports. When a viewport doesn't want a task bar icon, ImGuiViewportFlags_NoTaskBarIcon will be set on it.
+    bool        ConfigViewportsNoDecoration;    // = true           // Disable default OS window decoration flag for secondary viewports. When a viewport doesn't want window decorations, ImGuiViewportFlags_NoDecoration will be set on it. Enabling decoration can create subsequent issues at OS levels (e.g. minimum window size).
+    bool        ConfigViewportsNoDefaultParent; // = true           // When false: set secondary viewports' ParentViewportId to main viewport ID by default. Expects the platform backend to setup a parent/child relationship between the OS windows based on this value. Some backend may ignore this. Set to true if you want viewports to automatically be parent of main viewport, otherwise all viewports will be top-level OS windows.
+    bool        ConfigViewportsPlatformFocusSetsImGuiFocus;//= true // When a platform window is focused (e.g. using Alt+Tab, clicking Platform Title Bar), apply corresponding focus on imgui windows (may clear focus/active id from imgui windows location in other platform windows). In principle this is better enabled but we provide an opt-out, because some Linux window managers tend to eagerly focus windows (e.g. on mouse hover, or even a simple window pos/size change).
+
+    // DPI/Scaling options
+    // This may keep evolving during 1.92.x releases. Expect some turbulence.
+    bool        ConfigDpiScaleFonts;            // = false          // [EXPERIMENTAL] Automatically overwrite style.FontScaleDpi when Monitor DPI changes. This will scale fonts but _NOT_ scale sizes/padding for now.
+    bool        ConfigDpiScaleViewports;        // = false          // [EXPERIMENTAL] Scale Dear ImGui and Platform Windows when Monitor DPI changes.
+
     // Miscellaneous options
     // (you can visualize and interact with all options in 'Demo->Configuration')
     bool        MouseDrawCursor;                // = false          // Request ImGui to draw a mouse cursor for you (if you are on a platform without a mouse cursor). Cannot be easily renamed to 'io.ConfigXXX' because this is frequently used by backend implementations.
@@ -2516,6 +2623,7 @@
     IMGUI_API void  AddMouseButtonEvent(int button, bool down);             // Queue a mouse button change
     IMGUI_API void  AddMouseWheelEvent(float wheel_x, float wheel_y);       // Queue a mouse wheel update. wheel_y<0: scroll down, wheel_y>0: scroll up, wheel_x<0: scroll right, wheel_x>0: scroll left.
     IMGUI_API void  AddMouseSourceEvent(ImGuiMouseSource source);           // Queue a mouse source change (Mouse/TouchScreen/Pen)
+    IMGUI_API void  AddMouseViewportEvent(ImGuiID id);                      // Queue a mouse hovered viewport. Requires backend to set ImGuiBackendFlags_HasMouseHoveredViewport to call this (for multi-viewport support).
     IMGUI_API void  AddFocusEvent(bool focused);                            // Queue a gain/loss of focus for the application (generally based on OS/platform focus of your window)
     IMGUI_API void  AddInputCharacter(unsigned int c);                      // Queue a new character input
     IMGUI_API void  AddInputCharacterUTF16(ImWchar16 c);                    // Queue a new character input from a UTF-16 character, it can be a surrogate
@@ -2561,6 +2669,7 @@
     float       MouseWheel;                         // Mouse wheel Vertical: 1 unit scrolls about 5 lines text. >0 scrolls Up, <0 scrolls Down. Hold Shift to turn vertical scroll into horizontal scroll.
     float       MouseWheelH;                        // Mouse wheel Horizontal. >0 scrolls Left, <0 scrolls Right. Most users don't have a mouse with a horizontal wheel, may not be filled by all backends.
     ImGuiMouseSource MouseSource;                   // Mouse actual input peripheral (Mouse/TouchScreen/Pen).
+    ImGuiID     MouseHoveredViewport;               // (Optional) Modify using io.AddMouseViewportEvent(). With multi-viewports: viewport the OS mouse is hovering. If possible _IGNORING_ viewports with the ImGuiViewportFlags_NoInputs flag is much better (few backends can handle that). Set io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport if you can provide this info. If you don't imgui will infer the value using the rectangles and last focused time of the viewports it knows about (ignoring other OS windows).
     bool        KeyCtrl;                            // Keyboard modifier down: Ctrl (non-macOS), Cmd (macOS)
     bool        KeyShift;                           // Keyboard modifier down: Shift
     bool        KeyAlt;                             // Keyboard modifier down: Alt
@@ -2585,6 +2694,7 @@
     bool        MouseCtrlLeftAsRightClick;          // (OSX) Set to true when the current click was a Ctrl+Click that spawned a simulated right click
     float       MouseDownDuration[5];               // Duration the mouse button has been down (0.0f == just clicked)
     float       MouseDownDurationPrev[5];           // Previous time the mouse button has been down
+    ImVec2      MouseDragMaxDistanceAbs[5];         // Maximum distance, absolute, on each axis, of how much mouse has traveled from the clicking point
     float       MouseDragMaxDistanceSqr[5];         // Squared maximum distance of how much mouse has traveled from the clicking point (used for moving thresholds)
     float       PenPressure;                        // Touch/Pen pressure (0.0f to 1.0f, should be >0.0f only when MouseDown[0] == true). Helper storage currently unused by Dear ImGui.
     bool        AppFocusLost;                       // Only modify via AddFocusEvent()
@@ -2675,6 +2785,28 @@
     ImVec2  DesiredSize;    // Read-write.  Desired size, based on user's mouse position. Write to this field to restrain resizing.
 };
 
+// [ALPHA] Rarely used / very advanced uses only. Use with SetNextWindowClass() and DockSpace() functions.
+// Important: the content of this class is still highly WIP and likely to change and be refactored
+// before we stabilize Docking features. Please be mindful if using this.
+// Provide hints:
+// - To the platform backend via altered viewport flags (enable/disable OS decoration, OS task bar icons, etc.)
+// - To the platform backend for OS level parent/child relationships of viewport.
+// - To the docking system for various options and filtering.
+struct ImGuiWindowClass
+{
+    ImGuiID             ClassId;                    // User data. 0 = Default class (unclassed). Windows of different classes cannot be docked with each others.
+    ImGuiID             ParentViewportId;           // Hint for the platform backend. -1: use default. 0: request platform backend to not parent the platform. != 0: request platform backend to create a parent<>child relationship between the platform windows. Not conforming backends are free to e.g. parent every viewport to the main viewport or not.
+    ImGuiID             FocusRouteParentWindowId;   // ID of parent window for shortcut focus route evaluation, e.g. Shortcut() call from Parent Window will succeed when this window is focused.
+    ImGuiViewportFlags  ViewportFlagsOverrideSet;   // Viewport flags to set when a window of this class owns a viewport. This allows you to enforce OS decoration or task bar icon, override the defaults on a per-window basis.
+    ImGuiViewportFlags  ViewportFlagsOverrideClear; // Viewport flags to clear when a window of this class owns a viewport. This allows you to enforce OS decoration or task bar icon, override the defaults on a per-window basis.
+    ImGuiTabItemFlags   TabItemFlagsOverrideSet;    // [EXPERIMENTAL] TabItem flags to set when a window of this class gets submitted into a dock node tab bar. May use with ImGuiTabItemFlags_Leading or ImGuiTabItemFlags_Trailing.
+    ImGuiDockNodeFlags  DockNodeFlagsOverrideSet;   // [EXPERIMENTAL] Dock node flags to set when a window of this class is hosted by a dock node (it doesn't have to be selected!)
+    bool                DockingAlwaysTabBar;        // Set to true to enforce single floating windows of this class always having their own docking node (equivalent of setting the global io.ConfigDockingAlwaysTabBar)
+    bool                DockingAllowUnclassed;      // Set to true to allow windows of this class to be docked/merged with an unclassed window. // FIXME-DOCK: Move to DockNodeFlags override?
+
+    ImGuiWindowClass() { memset((void*)this, 0, sizeof(*this)); ParentViewportId = (ImGuiID)-1; DockingAllowUnclassed = true; }
+};
+
 // Data payload for Drag and Drop operations: AcceptDragDropPayload(), GetDragDropPayload()
 struct ImGuiPayload
 {
@@ -3920,11 +4052,24 @@
     ImGuiViewportFlags_None                     = 0,
     ImGuiViewportFlags_IsPlatformWindow         = 1 << 0,   // Represent a Platform Window
     ImGuiViewportFlags_IsPlatformMonitor        = 1 << 1,   // Represent a Platform Monitor (unused yet)
-    ImGuiViewportFlags_OwnedByApp               = 1 << 2,   // Platform Window: Is created/managed by the application (rather than a dear imgui backend)
+    ImGuiViewportFlags_OwnedByApp               = 1 << 2,   // Platform Window: Is created/managed by the user application? (rather than our backend)
+    ImGuiViewportFlags_NoDecoration             = 1 << 3,   // Platform Window: Disable platform decorations: title bar, borders, etc. (generally set all windows, but if ImGuiConfigFlags_ViewportsDecoration is set we only set this on popups/tooltips)
+    ImGuiViewportFlags_NoTaskBarIcon            = 1 << 4,   // Platform Window: Disable platform task bar icon (generally set on popups/tooltips, or all windows if ImGuiConfigFlags_ViewportsNoTaskBarIcon is set)
+    ImGuiViewportFlags_NoFocusOnAppearing       = 1 << 5,   // Platform Window: Don't take focus when created.
+    ImGuiViewportFlags_NoFocusOnClick           = 1 << 6,   // Platform Window: Don't take focus when clicked on.
+    ImGuiViewportFlags_NoInputs                 = 1 << 7,   // Platform Window: Make mouse pass through so we can drag this window while peaking behind it.
+    ImGuiViewportFlags_NoRendererClear          = 1 << 8,   // Platform Window: Renderer doesn't need to clear the framebuffer ahead (because we will fill it entirely).
+    ImGuiViewportFlags_NoAutoMerge              = 1 << 9,   // Platform Window: Avoid merging this window into another host window. This can only be set via ImGuiWindowClass viewport flags override (because we need to now ahead if we are going to create a viewport in the first place!).
+    ImGuiViewportFlags_TopMost                  = 1 << 10,  // Platform Window: Display on top (for tooltips only).
+    ImGuiViewportFlags_CanHostOtherWindows      = 1 << 11,  // Viewport can host multiple imgui windows (secondary viewports are associated to a single window). // FIXME: In practice there's still probably code making the assumption that this is always and only on the MainViewport. Will fix once we add support for "no main viewport".
+
+    // Output status flags (from Platform)
+    ImGuiViewportFlags_IsMinimized              = 1 << 12,  // Platform Window: Window is minimized, can skip render. When minimized we tend to avoid using the viewport pos/size for clipping window or testing if they are contained in the viewport.
+    ImGuiViewportFlags_IsFocused                = 1 << 13,  // Platform Window: Window is focused (last call to Platform_GetWindowFocus() returned true)
 };
 
 // - Currently represents the Platform Window created by the application which is hosting our Dear ImGui windows.
-// - In 'docking' branch with multi-viewport enabled, we extend this concept to have multiple active viewports.
+// - With multi-viewport enabled, we extend this concept to have multiple active viewports.
 // - In the future we will extend this concept further to also represent Platform Monitor and support a "no main platform window" operation mode.
 // - About Main Area vs Work Area:
 //   - Main Area = entire viewport.
@@ -3939,12 +4084,27 @@
     ImVec2              FramebufferScale;       // Density of the viewport for Retina display (always 1,1 on Windows, may be 2,2 etc on macOS/iOS). This will affect font rasterizer density.
     ImVec2              WorkPos;                // Work Area: Position of the viewport minus task bars, menus bars, status bars (>= Pos)
     ImVec2              WorkSize;               // Work Area: Size of the viewport minus task bars, menu bars, status bars (<= Size)
+    float               DpiScale;               // 1.0f = 96 DPI = No extra scale.
+    ImGuiID             ParentViewportId;       // (Advanced) 0: no parent. Instruct the platform backend to setup a parent/child relationship between platform windows.
+    ImGuiViewport*      ParentViewport;         // (Advanced) Direct shortcut to ImGui::FindViewportByID(ParentViewportId). NULL: no parent.
+    ImDrawData*         DrawData;               // The ImDrawData corresponding to this viewport. Valid after Render() and until the next call to NewFrame().
 
     // Platform/Backend Dependent Data
-    void*               PlatformHandle;         // void* to hold higher-level, platform window handle (e.g. HWND, GLFWWindow*, SDL_Window*)
-    void*               PlatformHandleRaw;      // void* to hold lower-level, platform-native window handle (under Win32 this is expected to be a HWND, unused for other platforms)
+    // Our design separate the Renderer and Platform backends to facilitate combining default backends with each others.
+    // When our create your own backend for a custom engine, it is possible that both Renderer and Platform will be handled
+    // by the same system and you may not need to use all the UserData/Handle fields.
+    // The library never uses those fields, they are merely storage to facilitate backend implementation.
+    void*               RendererUserData;       // void* to hold custom data structure for the renderer (e.g. swap chain, framebuffers etc.). generally set by your Renderer_CreateWindow function.
+    void*               PlatformUserData;       // void* to hold custom data structure for the OS / platform (e.g. windowing info, render context). generally set by your Platform_CreateWindow function.
+    void*               PlatformHandle;         // void* to hold higher-level, platform window handle (e.g. HWND for Win32 backend, Uint32 WindowID for SDL, GLFWWindow* for GLFW), for FindViewportByPlatformHandle().
+    void*               PlatformHandleRaw;      // void* to hold lower-level, platform-native window handle (always HWND on Win32 platform, unused for other platforms).
+    bool                PlatformWindowCreated;  // Platform window has been created (Platform_CreateWindow() has been called). This is false during the first frame where a viewport is being created.
+    bool                PlatformRequestMove;    // Platform window requested move (e.g. window was moved by the OS / host window manager, authoritative position will be OS window position)
+    bool                PlatformRequestResize;  // Platform window requested resize (e.g. window was resized by the OS / host window manager, authoritative size will be OS window size)
+    bool                PlatformRequestClose;   // Platform window requested closure (e.g. window was moved by the OS / host window manager, e.g. pressing ALT-F4)
 
     ImGuiViewport()     { memset((void*)this, 0, sizeof(*this)); }
+    ~ImGuiViewport()    { IM_ASSERT(PlatformUserData == NULL && RendererUserData == NULL); }
 
     // Helpers
     ImVec2              GetCenter() const       { return ImVec2(Pos.x + Size.x * 0.5f, Pos.y + Size.y * 0.5f); }
@@ -3952,7 +4112,53 @@
 };
 
 //-----------------------------------------------------------------------------
-// [SECTION] Platform Dependent Interfaces
+// [SECTION] ImGuiPlatformIO + other Platform Dependent Interfaces (ImGuiPlatformMonitor, ImGuiPlatformImeData)
+//-----------------------------------------------------------------------------
+
+// [BETA] (Optional) Multi-Viewport Support!
+// If you are new to Dear ImGui and trying to integrate it into your engine, you can probably ignore this for now.
+//
+// This feature allows you to seamlessly drag Dear ImGui windows outside of your application viewport.
+// This is achieved by creating new Platform/OS windows on the fly, and rendering into them.
+// Dear ImGui manages the viewport structures, and the backend create and maintain one Platform/OS window for each of those viewports.
+//
+// See Recap:   https://github.com/ocornut/imgui/wiki/Multi-Viewports
+// See Glossary https://github.com/ocornut/imgui/wiki/Glossary for details about some of the terminology.
+//
+// About the coordinates system:
+// - When multi-viewports are enabled, all Dear ImGui coordinates become absolute coordinates (same as OS coordinates!)
+// - So e.g. ImGui::SetNextWindowPos(ImVec2(0,0)) will position a window relative to your primary monitor!
+// - If you want to position windows relative to your main application viewport, use ImGui::GetMainViewport()->Pos as a base position.
+//
+// Steps to use multi-viewports in your application, when using a default backend from the examples/ folder:
+// - Application:  Enable feature with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
+// - Backend:      The backend initialization will setup all necessary ImGuiPlatformIO's functions and update monitors info every frame.
+// - Application:  In your main loop, call ImGui::UpdatePlatformWindows(), ImGui::RenderPlatformWindowsDefault() after EndFrame() or Render().
+// - Application:  Fix absolute coordinates used in ImGui::SetWindowPos() or ImGui::SetNextWindowPos() calls.
+//
+// Steps to use multi-viewports in your application, when using a custom backend:
+// - Important:    THIS IS NOT EASY TO DO and comes with many subtleties not described here!
+//                 It's also an experimental feature, so some of the requirements may evolve.
+//                 Consider using default backends if you can. Either way, carefully follow and refer to examples/ backends for details.
+// - Application:  Enable feature with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
+// - Backend:      Hook ImGuiPlatformIO's Platform_* and Renderer_* callbacks (see below).
+//                 Set 'io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports' and 'io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports'.
+//                 Update ImGuiPlatformIO's Monitors list every frame.
+//                 Update MousePos every frame, in absolute coordinates.
+// - Application:  In your main loop, call ImGui::UpdatePlatformWindows(), ImGui::RenderPlatformWindowsDefault() after EndFrame() or Render().
+//                 You may skip calling RenderPlatformWindowsDefault() if its API is not convenient for your needs. Read comments below.
+// - Application:  Fix absolute coordinates used in ImGui::SetWindowPos() or ImGui::SetNextWindowPos() calls.
+//
+// About ImGui::RenderPlatformWindowsDefault():
+// - This function is a mostly a _helper_ for the common-most cases, and to facilitate using default backends.
+// - You can check its simple source code to understand what it does.
+//   It basically iterates secondary viewports and call 4 functions that are setup in ImGuiPlatformIO, if available:
+//     Platform_RenderWindow(), Renderer_RenderWindow(), Platform_SwapBuffers(), Renderer_SwapBuffers()
+//   Those functions pointers exists only for the benefit of RenderPlatformWindowsDefault().
+// - If you have very specific rendering needs (e.g. flipping multiple swap-chain simultaneously, unusual sync/threading issues, etc.),
+//   you may be tempted to ignore RenderPlatformWindowsDefault() and write customized code to perform your renderingg.
+//   You may decide to setup the platform_io's *RenderWindow and *SwapBuffers pointers and call your functions through those pointers,
+//   or you may decide to never setup those pointers and call your code directly. They are a convenience, not an obligatory interface.
 //-----------------------------------------------------------------------------
 
 // Access via ImGui::GetPlatformIO()
@@ -3997,6 +4203,56 @@
     void*       Renderer_RenderState;
 
     //------------------------------------------------------------------
+    // Input - Interface with Platform & Renderer backends for Multi-Viewport support
+    //------------------------------------------------------------------
+
+    // For reference, the second column shows which function are generally calling the Platform Functions:
+    //   N = ImGui::NewFrame()                        ~ beginning of the dear imgui frame: read info from platform/OS windows (latest size/position)
+    //   F = ImGui::Begin(), ImGui::EndFrame()        ~ during the dear imgui frame
+    //   U = ImGui::UpdatePlatformWindows()           ~ after the dear imgui frame: create and update all platform/OS windows
+    //   R = ImGui::RenderPlatformWindowsDefault()    ~ render
+    //   D = ImGui::DestroyPlatformWindows()          ~ shutdown
+    // The general idea is that NewFrame() we will read the current Platform/OS state, and UpdatePlatformWindows() will write to it.
+
+    // The handlers are designed so we can mix and match two imgui_impl_xxxx files, one Platform backend and one Renderer backend.
+    // Custom engine backends will often provide both Platform and Renderer interfaces together and so may not need to use all functions.
+    // Platform functions are typically called _before_ their Renderer counterpart, apart from Destroy which are called the other way.
+
+    // Platform Backend functions (e.g. Win32, GLFW, SDL) ------------------- Called by -----
+    void    (*Platform_CreateWindow)(ImGuiViewport* vp);                    // . . U . .  // Create a new platform window for the given viewport
+    void    (*Platform_DestroyWindow)(ImGuiViewport* vp);                   // N . U . D  //
+    void    (*Platform_ShowWindow)(ImGuiViewport* vp);                      // . . U . .  // Newly created windows are initially hidden so SetWindowPos/Size/Title can be called on them before showing the window
+    void    (*Platform_SetWindowPos)(ImGuiViewport* vp, ImVec2 pos);        // . . U . .  // Set platform window position (given the upper-left corner of client area)
+    ImVec2  (*Platform_GetWindowPos)(ImGuiViewport* vp);                    // N . . . .  //
+    void    (*Platform_SetWindowSize)(ImGuiViewport* vp, ImVec2 size);      // . . U . .  // Set platform window client area size (ignoring OS decorations such as OS title bar etc.)
+    ImVec2  (*Platform_GetWindowSize)(ImGuiViewport* vp);                   // N . . . .  // Get platform window client area size
+    ImVec2  (*Platform_GetWindowFramebufferScale)(ImGuiViewport* vp);       // N . . . .  // Return viewport density. Always 1,1 on Windows, often 2,2 on Retina display on macOS/iOS. MUST BE INTEGER VALUES.
+    void    (*Platform_SetWindowFocus)(ImGuiViewport* vp);                  // N . . . .  // Move window to front and set input focus
+    bool    (*Platform_GetWindowFocus)(ImGuiViewport* vp);                  // . . U . .  //
+    bool    (*Platform_GetWindowMinimized)(ImGuiViewport* vp);              // N . . . .  // Get platform window minimized state. When minimized, we generally won't attempt to get/set size and contents will be culled more easily
+    void    (*Platform_SetWindowTitle)(ImGuiViewport* vp, const char* str); // . . U . .  // Set platform window title (given an UTF-8 string)
+    void    (*Platform_SetWindowAlpha)(ImGuiViewport* vp, float alpha);     // . . U . .  // (Optional) Setup global transparency (not per-pixel transparency)
+    void    (*Platform_UpdateWindow)(ImGuiViewport* vp);                    // . . U . .  // (Optional) Called by UpdatePlatformWindows(). Optional hook to allow the platform backend from doing general book-keeping every frame.
+    void    (*Platform_RenderWindow)(ImGuiViewport* vp, void* render_arg);  // . . . R .  // (Optional) Main rendering (platform side! This is often unused, or just setting a "current" context for OpenGL bindings). 'render_arg' is the value passed to RenderPlatformWindowsDefault().
+    void    (*Platform_SwapBuffers)(ImGuiViewport* vp, void* render_arg);   // . . . R .  // (Optional) Call Present/SwapBuffers (platform side! This is often unused!). 'render_arg' is the value passed to RenderPlatformWindowsDefault().
+    float   (*Platform_GetWindowDpiScale)(ImGuiViewport* vp);               // N . . . .  // (Optional) [BETA] FIXME-DPI: DPI handling: Return DPI scale for this viewport. 1.0f = 96 DPI.
+    void    (*Platform_OnChangedViewport)(ImGuiViewport* vp);               // . F . . .  // (Optional) [BETA] FIXME-DPI: DPI handling: Called during Begin() every time the viewport we are outputting into changes, so backend has a chance to swap fonts to adjust style.
+    ImVec4  (*Platform_GetWindowWorkAreaInsets)(ImGuiViewport* vp);         // N . . . .  // (Optional) [BETA] Get initial work area inset for the viewport (won't be covered by main menu bar, dockspace over viewport etc.). Default to (0,0),(0,0). 'safeAreaInsets' in iOS land, 'DisplayCutout' in Android land.
+    int     (*Platform_CreateVkSurface)(ImGuiViewport* vp, ImU64 vk_inst, const void* vk_allocators, ImU64* out_vk_surface); // (Optional) For a Vulkan Renderer to call into Platform code (since the surface creation needs to tie them both).
+
+    // Renderer Backend functions (e.g. DirectX, OpenGL, Vulkan) ------------ Called by -----
+    void    (*Renderer_CreateWindow)(ImGuiViewport* vp);                    // . . U . .  // Create swap chain, frame buffers etc. (called after Platform_CreateWindow)
+    void    (*Renderer_DestroyWindow)(ImGuiViewport* vp);                   // N . U . D  // Destroy swap chain, frame buffers etc. (called before Platform_DestroyWindow)
+    void    (*Renderer_SetWindowSize)(ImGuiViewport* vp, ImVec2 size);      // . . U . .  // Resize swap chain, frame buffers etc. (called after Platform_SetWindowSize)
+    void    (*Renderer_RenderWindow)(ImGuiViewport* vp, void* render_arg);  // . . . R .  // (Optional) Clear framebuffer, setup render target, then render the viewport->DrawData. 'render_arg' is the value passed to RenderPlatformWindowsDefault().
+    void    (*Renderer_SwapBuffers)(ImGuiViewport* vp, void* render_arg);   // . . . R .  // (Optional) Call Present/SwapBuffers. 'render_arg' is the value passed to RenderPlatformWindowsDefault().
+
+    // (Optional) Monitor list
+    // - Updated by: app/backend. Update every frame to dynamically support changing monitor or DPI configuration.
+    // - Used by: dear imgui to query DPI info, clamp popups/tooltips within same monitor and not have them straddle monitors.
+    ImVector<ImGuiPlatformMonitor>  Monitors;
+
+    //------------------------------------------------------------------
     // Output
     //------------------------------------------------------------------
 
@@ -4004,6 +4260,10 @@
     // The ImGui_ImplXXXX_RenderDrawData() function of each backend generally access this via ImDrawData::Textures which points to this. The array is available here mostly because backends will want to destroy textures on shutdown.
     ImVector<ImTextureData*>        Textures;           // List of textures used by Dear ImGui (most often 1) + contents of external texture list is automatically appended into this.
 
+    // Viewports list (the list is updated by calling ImGui::EndFrame or ImGui::Render)
+    // (in the future we will attempt to organize this feature to remove the need for a "main viewport")
+    ImVector<ImGuiViewport*>        Viewports;          // Main viewports, followed by all secondary viewports.
+
     //------------------------------------------------------------------
     // Functions
     //------------------------------------------------------------------
@@ -4012,6 +4272,17 @@
     IMGUI_API void ClearRendererHandlers();    // Clear all Renderer_XXX fields. Typically called on Renderer Backend shutdown.
 };
 
+// (Optional) This is required when enabling multi-viewport. Represent the bounds of each connected monitor/display and their DPI.
+// We use this information for multiple DPI support + clamping the position of popups and tooltips so they don't straddle multiple monitors.
+struct ImGuiPlatformMonitor
+{
+    ImVec2  MainPos, MainSize;      // Coordinates of the area displayed on this monitor (Min = upper left, Max = bottom right)
+    ImVec2  WorkPos, WorkSize;      // Coordinates without task bars / side bars / menu bars. Used to avoid positioning popups/tooltips inside this region. If you don't have this info, please copy the value for MainPos/MainSize.
+    float   DpiScale;               // 1.0f = 96 DPI
+    void*   PlatformHandle;         // Backend dependant data (e.g. HMONITOR, GLFWmonitor*, SDL Display Index, NSScreen*)
+    ImGuiPlatformMonitor()          { MainPos = MainSize = WorkPos = WorkSize = ImVec2(0, 0); DpiScale = 1.0f; PlatformHandle = NULL; }
+};
+
 // (Optional) Support for IME (Input Method Editor) via the platform_io.Platform_SetImeDataFn() function. Handler is called during EndFrame().
 struct ImGuiPlatformImeData
 {

diff --git a/imgui_demo.cpp b/imgui_demo.cpp
index c0c4de9..d74a8db 100644
--- a/imgui_demo.cpp
+++ b/imgui_demo.cpp

@@ -118,6 +118,7 @@
 // [SECTION] Example App: Fullscreen window / ShowExampleAppFullscreen()
 // [SECTION] Example App: Manipulating window titles / ShowExampleAppWindowTitles()
 // [SECTION] Example App: Custom Rendering using ImDrawList API / ShowExampleAppCustomRendering()
+// [SECTION] Example App: Docking, DockSpace / ShowExampleAppDockSpace()
 // [SECTION] Example App: Documents Handling / ShowExampleAppDocuments()
 // [SECTION] Example App: Assets Browser / ShowExampleAppAssetsBrowser()
 
@@ -237,6 +238,7 @@
 static void ShowExampleAppAssetsBrowser(bool* p_open);
 static void ShowExampleAppConsole(bool* p_open);
 static void ShowExampleAppCustomRendering(bool* p_open);
+static void ShowExampleAppDockSpace(bool* p_open);
 static void ShowExampleAppDocuments(bool* p_open);
 static void ShowExampleAppLog(bool* p_open);
 static void ShowExampleAppLayout(bool* p_open);
@@ -282,6 +284,16 @@
     }
 }
 
+static void ShowDockingDisabledMessage()
+{
+    ImGuiIO& io = ImGui::GetIO();
+    ImGui::Text("ERROR: Docking is not enabled! See Demo > Configuration.");
+    ImGui::Text("Set io.ConfigFlags |= ImGuiConfigFlags_DockingEnable in your code, or ");
+    ImGui::SameLine(0.0f, 0.0f);
+    if (ImGui::SmallButton("click here"))
+        io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;
+}
+
 // Helper to wire demo markers located in code to an interactive browser
 typedef void (*ImGuiDemoMarkerCallback)(const char* file, int line, const char* section, void* user_data);
 extern ImGuiDemoMarkerCallback      GImGuiDemoMarkerCallback;
@@ -303,6 +315,7 @@
     bool ShowAppConsole = false;
     bool ShowAppCustomRendering = false;
     bool ShowAppDocuments = false;
+    bool ShowAppDockSpace = false;
     bool ShowAppLog = false;
     bool ShowAppLayout = false;
     bool ShowAppPropertyEditor = false;
@@ -344,7 +357,8 @@
 
     // Examples Apps (accessible from the "Examples" menu)
     if (demo_data.ShowMainMenuBar)          { ShowExampleAppMainMenuBar(); }
-    if (demo_data.ShowAppDocuments)         { ShowExampleAppDocuments(&demo_data.ShowAppDocuments); }
+    if (demo_data.ShowAppDockSpace)         { ShowExampleAppDockSpace(&demo_data.ShowAppDockSpace); } // Important: Process the Docking app first, as explicit DockSpace() nodes needs to be submitted early (read comments near the DockSpace function)
+    if (demo_data.ShowAppDocuments)         { ShowExampleAppDocuments(&demo_data.ShowAppDocuments); } // ...process the Document app next, as it may also use a DockSpace()
     if (demo_data.ShowAppAssetsBrowser)     { ShowExampleAppAssetsBrowser(&demo_data.ShowAppAssetsBrowser); }
     if (demo_data.ShowAppConsole)           { ShowExampleAppConsole(&demo_data.ShowAppConsole); }
     if (demo_data.ShowAppCustomRendering)   { ShowExampleAppCustomRendering(&demo_data.ShowAppCustomRendering); }
@@ -381,6 +395,7 @@
     static bool no_nav = false;
     static bool no_background = false;
     static bool no_bring_to_front = false;
+    static bool no_docking = false;
     static bool unsaved_document = false;
 
     ImGuiWindowFlags window_flags = 0;
@@ -393,6 +408,7 @@
     if (no_nav)             window_flags |= ImGuiWindowFlags_NoNav;
     if (no_background)      window_flags |= ImGuiWindowFlags_NoBackground;
     if (no_bring_to_front)  window_flags |= ImGuiWindowFlags_NoBringToFrontOnFocus;
+    if (no_docking)         window_flags |= ImGuiWindowFlags_NoDocking;
     if (unsaved_document)   window_flags |= ImGuiWindowFlags_UnsavedDocument;
     if (no_close)           p_open = NULL; // Don't pass our bool* to Begin
 
@@ -505,6 +521,54 @@
             ImGui::Checkbox("io.ConfigNavCursorVisibleAlways", &io.ConfigNavCursorVisibleAlways);
             ImGui::SameLine(); HelpMarker("Navigation cursor is always visible.");
 
+            ImGui::SeparatorText("Docking");
+            ImGui::CheckboxFlags("io.ConfigFlags: DockingEnable", &io.ConfigFlags, ImGuiConfigFlags_DockingEnable);
+            ImGui::SameLine();
+            if (io.ConfigDockingWithShift)
+                HelpMarker("Drag from window title bar or their tab to dock/undock. Hold SHIFT to enable docking.\n\nDrag from window menu button (upper-left button) to undock an entire node (all windows).");
+            else
+                HelpMarker("Drag from window title bar or their tab to dock/undock. Hold SHIFT to disable docking.\n\nDrag from window menu button (upper-left button) to undock an entire node (all windows).");
+            if (io.ConfigFlags & ImGuiConfigFlags_DockingEnable)
+            {
+                ImGui::Indent();
+                ImGui::Checkbox("io.ConfigDockingNoSplit", &io.ConfigDockingNoSplit);
+                ImGui::SameLine(); HelpMarker("Simplified docking mode: disable window splitting, so docking is limited to merging multiple windows together into tab-bars.");
+                ImGui::Checkbox("io.ConfigDockingNoDockingOver", &io.ConfigDockingNoDockingOver);
+                ImGui::SameLine(); HelpMarker("Simplified docking mode: disable window merging into a same tab-bar, so docking is limited to splitting windows.");
+                ImGui::Checkbox("io.ConfigDockingWithShift", &io.ConfigDockingWithShift);
+                ImGui::SameLine(); HelpMarker("Enable docking when holding Shift only (allow to drop in wider space, reduce visual noise)");
+                ImGui::Checkbox("io.ConfigDockingAlwaysTabBar", &io.ConfigDockingAlwaysTabBar);
+                ImGui::SameLine(); HelpMarker("Create a docking node and tab-bar on single floating windows.");
+                ImGui::Checkbox("io.ConfigDockingTransparentPayload", &io.ConfigDockingTransparentPayload);
+                ImGui::SameLine(); HelpMarker("Make window or viewport transparent when docking and only display docking boxes on the target viewport. Useful if rendering of multiple viewport cannot be synced. Best used with ConfigViewportsNoAutoMerge.");
+                ImGui::Unindent();
+            }
+
+            ImGui::SeparatorText("Multi-viewports");
+            ImGui::CheckboxFlags("io.ConfigFlags: ViewportsEnable", &io.ConfigFlags, ImGuiConfigFlags_ViewportsEnable);
+            ImGui::SameLine(); HelpMarker("[beta] Enable beta multi-viewports support. See ImGuiPlatformIO for details.");
+            if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
+            {
+                ImGui::Indent();
+                ImGui::Checkbox("io.ConfigViewportsNoAutoMerge", &io.ConfigViewportsNoAutoMerge);
+                ImGui::SameLine(); HelpMarker("Set to make all floating imgui windows always create their own viewport. Otherwise, they are merged into the main host viewports when overlapping it.");
+                ImGui::Checkbox("io.ConfigViewportsNoTaskBarIcon", &io.ConfigViewportsNoTaskBarIcon);
+                ImGui::SameLine(); HelpMarker("(note: some platform backends may not reflect a change of this value for existing viewports, and may need the viewport to be recreated)");
+                ImGui::Checkbox("io.ConfigViewportsNoDecoration", &io.ConfigViewportsNoDecoration);
+                ImGui::SameLine(); HelpMarker("(note: some platform backends may not reflect a change of this value for existing viewports, and may need the viewport to be recreated)");
+                ImGui::Checkbox("io.ConfigViewportsNoDefaultParent", &io.ConfigViewportsNoDefaultParent);
+                ImGui::SameLine(); HelpMarker("(note: some platform backends may not reflect a change of this value for existing viewports, and may need the viewport to be recreated)");
+                ImGui::Checkbox("io.ConfigViewportsPlatformFocusSetsImGuiFocus", &io.ConfigViewportsPlatformFocusSetsImGuiFocus);
+                ImGui::SameLine(); HelpMarker("When a platform window is focused (e.g. using Alt+Tab, clicking Platform Title Bar), apply corresponding focus on imgui windows (may clear focus/active id from imgui windows location in other platform windows). In principle this is better enabled but we provide an opt-out, because some Linux window managers tend to eagerly focus windows (e.g. on mouse hover, or even a simple window pos/size change).");
+                ImGui::Unindent();
+            }
+
+            //ImGui::SeparatorText("DPI/Scaling");
+            //ImGui::Checkbox("io.ConfigDpiScaleFonts", &io.ConfigDpiScaleFonts);
+            //ImGui::SameLine(); HelpMarker("Experimental: Automatically update style.FontScaleDpi when Monitor DPI changes. This will scale fonts but NOT style sizes/padding for now.");
+            //ImGui::Checkbox("io.ConfigDpiScaleViewports", &io.ConfigDpiScaleViewports);
+            //ImGui::SameLine(); HelpMarker("Experimental: Scale Dear ImGui and Platform Windows when Monitor DPI changes.");
+
             ImGui::SeparatorText("Windows");
             ImGui::Checkbox("io.ConfigWindowsResizeFromEdges", &io.ConfigWindowsResizeFromEdges);
             ImGui::SameLine(); HelpMarker("Enable resizing of windows from their edges and from the lower-left corner.\nThis requires ImGuiBackendFlags_HasMouseCursors for better mouse cursor feedback.");
@@ -570,13 +634,18 @@
                 "Those flags are set by the backends (imgui_impl_xxx files) to specify their capabilities.\n"
                 "Here we expose them as read-only fields to avoid breaking interactions with your backend.");
 
+            // Make a local copy to avoid modifying actual backend flags.
             // FIXME: Maybe we need a BeginReadonly() equivalent to keep label bright?
             ImGui::BeginDisabled();
-            ImGui::CheckboxFlags("io.BackendFlags: HasGamepad",           &io.BackendFlags, ImGuiBackendFlags_HasGamepad);
-            ImGui::CheckboxFlags("io.BackendFlags: HasMouseCursors",      &io.BackendFlags, ImGuiBackendFlags_HasMouseCursors);
-            ImGui::CheckboxFlags("io.BackendFlags: HasSetMousePos",       &io.BackendFlags, ImGuiBackendFlags_HasSetMousePos);
-            ImGui::CheckboxFlags("io.BackendFlags: RendererHasVtxOffset", &io.BackendFlags, ImGuiBackendFlags_RendererHasVtxOffset);
-            ImGui::CheckboxFlags("io.BackendFlags: RendererHasTextures",  &io.BackendFlags, ImGuiBackendFlags_RendererHasTextures);
+            ImGui::CheckboxFlags("io.BackendFlags: HasGamepad",             &io.BackendFlags, ImGuiBackendFlags_HasGamepad);
+            ImGui::CheckboxFlags("io.BackendFlags: HasMouseCursors",        &io.BackendFlags, ImGuiBackendFlags_HasMouseCursors);
+            ImGui::CheckboxFlags("io.BackendFlags: HasSetMousePos",         &io.BackendFlags, ImGuiBackendFlags_HasSetMousePos);
+            ImGui::CheckboxFlags("io.BackendFlags: PlatformHasViewports",   &io.BackendFlags, ImGuiBackendFlags_PlatformHasViewports);
+            ImGui::CheckboxFlags("io.BackendFlags: HasMouseHoveredViewport",&io.BackendFlags, ImGuiBackendFlags_HasMouseHoveredViewport);
+            ImGui::CheckboxFlags("io.BackendFlags: HasParentViewport",      &io.BackendFlags, ImGuiBackendFlags_HasParentViewport);
+            ImGui::CheckboxFlags("io.BackendFlags: RendererHasVtxOffset",   &io.BackendFlags, ImGuiBackendFlags_RendererHasVtxOffset);
+            ImGui::CheckboxFlags("io.BackendFlags: RendererHasTextures",    &io.BackendFlags, ImGuiBackendFlags_RendererHasTextures);
+            ImGui::CheckboxFlags("io.BackendFlags: RendererHasViewports",   &io.BackendFlags, ImGuiBackendFlags_RendererHasViewports);
             ImGui::EndDisabled();
 
             ImGui::TreePop();
@@ -628,6 +697,7 @@
             ImGui::TableNextColumn(); ImGui::Checkbox("No nav", &no_nav);
             ImGui::TableNextColumn(); ImGui::Checkbox("No background", &no_background);
             ImGui::TableNextColumn(); ImGui::Checkbox("No bring to front", &no_bring_to_front);
+            ImGui::TableNextColumn(); ImGui::Checkbox("No docking", &no_docking);
             ImGui::TableNextColumn(); ImGui::Checkbox("Unsaved document", &unsaved_document);
             ImGui::EndTable();
         }
@@ -670,6 +740,7 @@
             ImGui::MenuItem("Console", NULL, &demo_data->ShowAppConsole);
             ImGui::MenuItem("Custom rendering", NULL, &demo_data->ShowAppCustomRendering);
             ImGui::MenuItem("Documents", NULL, &demo_data->ShowAppDocuments);
+            ImGui::MenuItem("Dockspace", NULL, &demo_data->ShowAppDockSpace);
             ImGui::MenuItem("Log", NULL, &demo_data->ShowAppLog);
             ImGui::MenuItem("Property editor", NULL, &demo_data->ShowAppPropertyEditor);
             ImGui::MenuItem("Simple layout", NULL, &demo_data->ShowAppLayout);
@@ -2210,18 +2281,24 @@
             "IsWindowFocused() = %d\n"
             "IsWindowFocused(_ChildWindows) = %d\n"
             "IsWindowFocused(_ChildWindows|_NoPopupHierarchy) = %d\n"
+            "IsWindowFocused(_ChildWindows|_DockHierarchy) = %d\n"
             "IsWindowFocused(_ChildWindows|_RootWindow) = %d\n"
             "IsWindowFocused(_ChildWindows|_RootWindow|_NoPopupHierarchy) = %d\n"
+            "IsWindowFocused(_ChildWindows|_RootWindow|_DockHierarchy) = %d\n"
             "IsWindowFocused(_RootWindow) = %d\n"
             "IsWindowFocused(_RootWindow|_NoPopupHierarchy) = %d\n"
+            "IsWindowFocused(_RootWindow|_DockHierarchy) = %d\n"
             "IsWindowFocused(_AnyWindow) = %d\n",
             ImGui::IsWindowFocused(),
             ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows),
             ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows | ImGuiFocusedFlags_NoPopupHierarchy),
+            ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows | ImGuiFocusedFlags_DockHierarchy),
             ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows | ImGuiFocusedFlags_RootWindow),
             ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows | ImGuiFocusedFlags_RootWindow | ImGuiFocusedFlags_NoPopupHierarchy),
+            ImGui::IsWindowFocused(ImGuiFocusedFlags_ChildWindows | ImGuiFocusedFlags_RootWindow | ImGuiFocusedFlags_DockHierarchy),
             ImGui::IsWindowFocused(ImGuiFocusedFlags_RootWindow),
             ImGui::IsWindowFocused(ImGuiFocusedFlags_RootWindow | ImGuiFocusedFlags_NoPopupHierarchy),
+            ImGui::IsWindowFocused(ImGuiFocusedFlags_RootWindow | ImGuiFocusedFlags_DockHierarchy),
             ImGui::IsWindowFocused(ImGuiFocusedFlags_AnyWindow));
 
         // Testing IsWindowHovered() function with its various flags.
@@ -2231,10 +2308,13 @@
             "IsWindowHovered(_AllowWhenBlockedByActiveItem) = %d\n"
             "IsWindowHovered(_ChildWindows) = %d\n"
             "IsWindowHovered(_ChildWindows|_NoPopupHierarchy) = %d\n"
+            "IsWindowHovered(_ChildWindows|_DockHierarchy) = %d\n"
             "IsWindowHovered(_ChildWindows|_RootWindow) = %d\n"
             "IsWindowHovered(_ChildWindows|_RootWindow|_NoPopupHierarchy) = %d\n"
+            "IsWindowHovered(_ChildWindows|_RootWindow|_DockHierarchy) = %d\n"
             "IsWindowHovered(_RootWindow) = %d\n"
             "IsWindowHovered(_RootWindow|_NoPopupHierarchy) = %d\n"
+            "IsWindowHovered(_RootWindow|_DockHierarchy) = %d\n"
             "IsWindowHovered(_ChildWindows|_AllowWhenBlockedByPopup) = %d\n"
             "IsWindowHovered(_AnyWindow) = %d\n"
             "IsWindowHovered(_Stationary) = %d\n",
@@ -2243,10 +2323,13 @@
             ImGui::IsWindowHovered(ImGuiHoveredFlags_AllowWhenBlockedByActiveItem),
             ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows),
             ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_NoPopupHierarchy),
+            ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_DockHierarchy),
             ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_RootWindow),
             ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_RootWindow | ImGuiHoveredFlags_NoPopupHierarchy),
+            ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_RootWindow | ImGuiHoveredFlags_DockHierarchy),
             ImGui::IsWindowHovered(ImGuiHoveredFlags_RootWindow),
             ImGui::IsWindowHovered(ImGuiHoveredFlags_RootWindow | ImGuiHoveredFlags_NoPopupHierarchy),
+            ImGui::IsWindowHovered(ImGuiHoveredFlags_RootWindow | ImGuiHoveredFlags_DockHierarchy),
             ImGui::IsWindowHovered(ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_AllowWhenBlockedByPopup),
             ImGui::IsWindowHovered(ImGuiHoveredFlags_AnyWindow),
             ImGui::IsWindowHovered(ImGuiHoveredFlags_Stationary));
@@ -2259,10 +2342,13 @@
 
         // Calling IsItemHovered() after begin returns the hovered status of the title bar.
         // This is useful in particular if you want to create a context menu associated to the title bar of a window.
+        // This will also work when docked into a Tab (the Tab replace the Title Bar and guarantee the same properties).
         static bool test_window = false;
         ImGui::Checkbox("Hovered/Active tests after Begin() for title bar testing", &test_window);
         if (test_window)
         {
+            // FIXME-DOCK: This window cannot be docked within the ImGui Demo window, this will cause a feedback loop and get them stuck.
+            // Could we fix this through an ImGuiWindowClass feature? Or an API call to tag our parent as "don't skip items"?
             ImGui::Begin("Title bar Hovered/Active tests", &test_window);
             if (ImGui::BeginPopupContextItem()) // <-- This is using IsItemHovered()
             {
@@ -8245,6 +8331,12 @@
         ImGui::Text("Emscripten: %d.%d.%d", __EMSCRIPTEN_major__, __EMSCRIPTEN_minor__, __EMSCRIPTEN_tiny__);
 #endif
 #endif
+#ifdef IMGUI_HAS_VIEWPORT
+        ImGui::Text("define: IMGUI_HAS_VIEWPORT");
+#endif
+#ifdef IMGUI_HAS_DOCK
+        ImGui::Text("define: IMGUI_HAS_DOCK");
+#endif
 #ifdef NDEBUG
         ImGui::Text("define: NDEBUG");
 #endif
@@ -8273,7 +8365,20 @@
         if (io.ConfigFlags & ImGuiConfigFlags_NoMouse)                  ImGui::Text(" NoMouse");
         if (io.ConfigFlags & ImGuiConfigFlags_NoMouseCursorChange)      ImGui::Text(" NoMouseCursorChange");
         if (io.ConfigFlags & ImGuiConfigFlags_NoKeyboard)               ImGui::Text(" NoKeyboard");
+        if (io.ConfigFlags & ImGuiConfigFlags_DockingEnable)            ImGui::Text(" DockingEnable");
+        if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)          ImGui::Text(" ViewportsEnable");
         if (io.MouseDrawCursor)                                         ImGui::Text("io.MouseDrawCursor");
+        if (io.ConfigDpiScaleFonts)                                     ImGui::Text("io.ConfigDpiScaleFonts");
+        if (io.ConfigDpiScaleViewports)                                 ImGui::Text("io.ConfigDpiScaleViewports");
+        if (io.ConfigViewportsNoAutoMerge)                              ImGui::Text("io.ConfigViewportsNoAutoMerge");
+        if (io.ConfigViewportsNoTaskBarIcon)                            ImGui::Text("io.ConfigViewportsNoTaskBarIcon");
+        if (io.ConfigViewportsNoDecoration)                             ImGui::Text("io.ConfigViewportsNoDecoration");
+        if (io.ConfigViewportsNoDefaultParent)                          ImGui::Text("io.ConfigViewportsNoDefaultParent");
+        if (io.ConfigDockingNoSplit)                                    ImGui::Text("io.ConfigDockingNoSplit");
+        if (io.ConfigDockingNoDockingOver)                              ImGui::Text("io.ConfigDockingNoDockingOver");
+        if (io.ConfigDockingWithShift)                                  ImGui::Text("io.ConfigDockingWithShift");
+        if (io.ConfigDockingAlwaysTabBar)                               ImGui::Text("io.ConfigDockingAlwaysTabBar");
+        if (io.ConfigDockingTransparentPayload)                         ImGui::Text("io.ConfigDockingTransparentPayload");
         if (io.ConfigMacOSXBehaviors)                                   ImGui::Text("io.ConfigMacOSXBehaviors");
         if (io.ConfigNavMoveSetMousePos)                                ImGui::Text("io.ConfigNavMoveSetMousePos");
         if (io.ConfigNavCaptureKeyboard)                                ImGui::Text("io.ConfigNavCaptureKeyboard");
@@ -8285,8 +8390,12 @@
         if (io.BackendFlags & ImGuiBackendFlags_HasGamepad)             ImGui::Text(" HasGamepad");
         if (io.BackendFlags & ImGuiBackendFlags_HasMouseCursors)        ImGui::Text(" HasMouseCursors");
         if (io.BackendFlags & ImGuiBackendFlags_HasSetMousePos)         ImGui::Text(" HasSetMousePos");
+        if (io.BackendFlags & ImGuiBackendFlags_PlatformHasViewports)   ImGui::Text(" PlatformHasViewports");
+        if (io.BackendFlags & ImGuiBackendFlags_HasMouseHoveredViewport)ImGui::Text(" HasMouseHoveredViewport");
+        if (io.BackendFlags & ImGuiBackendFlags_HasParentViewport)      ImGui::Text(" HasParentViewport");
         if (io.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset)   ImGui::Text(" RendererHasVtxOffset");
         if (io.BackendFlags & ImGuiBackendFlags_RendererHasTextures)    ImGui::Text(" RendererHasTextures");
+        if (io.BackendFlags & ImGuiBackendFlags_RendererHasViewports)   ImGui::Text(" RendererHasViewports");
         ImGui::Separator();
         ImGui::Text("io.Fonts: %d fonts, Flags: 0x%08X, TexSize: %d,%d", io.Fonts->Fonts.Size, io.Fonts->Flags, io.Fonts->TexData->Width, io.Fonts->TexData->Height);
         ImGui::Text("io.Fonts->FontLoaderName: %s", io.Fonts->FontLoaderName ? io.Fonts->FontLoaderName : "NULL");
@@ -8394,10 +8503,10 @@
             style._NextFrameFontSizeBase = style.FontSizeBase; // FIXME: Temporary hack until we finish remaining work.
         SameLine(0.0f, 0.0f); Text(" (out %.2f)", GetFontSize());
         DragFloat("FontScaleMain", &style.FontScaleMain, 0.02f, 0.5f, 4.0f);
-        //BeginDisabled(GetIO().ConfigDpiScaleFonts);
+        BeginDisabled(GetIO().ConfigDpiScaleFonts);
         DragFloat("FontScaleDpi", &style.FontScaleDpi, 0.02f, 0.5f, 4.0f);
-        //SetItemTooltip("When io.ConfigDpiScaleFonts is set, this value is automatically overwritten.");
-        //EndDisabled();
+        SetItemTooltip("When io.ConfigDpiScaleFonts is set, this value is automatically overwritten.");
+        EndDisabled();
 
         // Simplified Settings (expose floating-pointer border sizes as boolean representing 0.0f or 1.0f)
         if (SliderFloat("FrameRounding", &style.FrameRounding, 0.0f, 12.0f, "%.0f"))
@@ -8504,6 +8613,11 @@
             SliderFloat("ImageRounding", &style.ImageRounding, 0.0f, 12.0f, "%.0f");
             SliderFloat("ImageBorderSize", &style.ImageBorderSize, 0.0f, 1.0f, "%.0f");
 
+            SeparatorText("Docking");
+            //SetCursorPosX(GetCursorPosX() + CalcItemWidth() - GetFrameHeight());
+            Checkbox("DockingNodeHasCloseButton", &style.DockingNodeHasCloseButton);
+            SliderFloat("DockingSeparatorSize", &style.DockingSeparatorSize, 0.0f, 12.0f, "%.0f");
+
             SeparatorText("Tooltips");
             for (int n = 0; n < 2; n++)
                 if (TreeNodeEx(n == 0 ? "HoverFlagsForTooltipMouse" : "HoverFlagsForTooltipNav"))
@@ -9761,6 +9875,8 @@
         else
         {
             ImGui::Text("(Hold Shift to display a dummy viewport)");
+            if (ImGui::IsWindowDocked())
+                ImGui::Text("Warning: Sizing Constraints won't work if the window is docked!");
             if (ImGui::Button("Set 200x200")) { ImGui::SetWindowSize(ImVec2(200, 200)); } ImGui::SameLine();
             if (ImGui::Button("Set 500x500")) { ImGui::SetWindowSize(ImVec2(500, 500)); } ImGui::SameLine();
             if (ImGui::Button("Set 800x200")) { ImGui::SetWindowSize(ImVec2(800, 200)); }
@@ -9787,7 +9903,7 @@
 {
     static int location = 0;
     ImGuiIO& io = ImGui::GetIO();
-    ImGuiWindowFlags window_flags = ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoFocusOnAppearing | ImGuiWindowFlags_NoNav;
+    ImGuiWindowFlags window_flags = ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_NoDocking | ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoFocusOnAppearing | ImGuiWindowFlags_NoNav;
     if (location >= 0)
     {
         const float PAD = 10.0f;
@@ -9800,6 +9916,7 @@
         window_pos_pivot.x = (location & 1) ? 1.0f : 0.0f;
         window_pos_pivot.y = (location & 2) ? 1.0f : 0.0f;
         ImGui::SetNextWindowPos(window_pos, ImGuiCond_Always, window_pos_pivot);
+        ImGui::SetNextWindowViewport(viewport->ID);
         window_flags |= ImGuiWindowFlags_NoMove;
     }
     else if (location == -2)
@@ -10220,6 +10337,164 @@
 }
 
 //-----------------------------------------------------------------------------
+// [SECTION] Example App: Docking, DockSpace / ShowExampleAppDockSpace()
+//-----------------------------------------------------------------------------
+
+struct ImGuiDemoDockspaceArgs
+{
+    bool                IsFullscreen = true;
+    bool                KeepWindowPadding = false; // Keep WindowPadding to help understand that DockSpace() is a widget inside the window.
+    ImGuiDockNodeFlags  DockSpaceFlags  = ImGuiDockNodeFlags_None;
+};
+
+// THIS IS A DEMO FOR ADVANCED USAGE OF DockSpace().
+// MOST REGULAR APPLICATIONS WANTING TO ALLOW DOCKING WINDOWS ON THE EDGE OF YOUR SCREEN CAN SIMPLY USE:
+//    ImGui::NewFrame(); + ImGui::DockSpaceOverViewport();                                                   // Create a dockspace in main viewport
+// OR:
+//    ImGui::NewFrame(); + ImGui::DockSpaceOverViewport(0, nullptr, ImGuiDockNodeFlags_PassthruCentralNode); // Create a dockspace in main viewport, where central node is transparent.
+// Demonstrate using DockSpace() to create an explicit docking node within an existing window, with various options.
+// Read https://github.com/ocornut/imgui/wiki/Docking for details.
+// The reasons we do not use DockSpaceOverViewport() in this demo is because:
+// - (1) we allow the host window to be floating/moveable instead of filling the viewport (when args->IsFullscreen == false)
+//       which is mostly to showcase the idea that DockSpace() may be submitted anywhere.
+//       Also see 'Demo->Examples->Documents' for a less abstract version of this.
+// - (2) we allow the host window to have padding (when args->UsePadding == true)
+// - (3) we expose variety of other flags.
+static void ShowExampleAppDockSpaceAdvanced(ImGuiDemoDockspaceArgs* args, bool* p_open)
+{
+    ImGuiDockNodeFlags dockspace_flags = args->DockSpaceFlags;
+
+    // We are using the ImGuiWindowFlags_NoDocking flag to make the parent window not dockable into,
+    // because it would be confusing to have two docking targets within each others.
+    ImGuiWindowFlags window_flags = ImGuiWindowFlags_NoDocking;
+    if (args->IsFullscreen)
+    {
+        // Fullscreen dockspace: practically the same as calling DockSpaceOverViewport();
+        const ImGuiViewport* viewport = ImGui::GetMainViewport();
+        ImGui::SetNextWindowPos(viewport->WorkPos);
+        ImGui::SetNextWindowSize(viewport->WorkSize);
+        ImGui::SetNextWindowViewport(viewport->ID);
+        ImGui::PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
+        ImGui::PushStyleVar(ImGuiStyleVar_WindowBorderSize, 0.0f);
+        window_flags |= ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoCollapse | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoMove;
+        window_flags |= ImGuiWindowFlags_NoBringToFrontOnFocus | ImGuiWindowFlags_NoNavFocus;
+        window_flags |= ImGuiWindowFlags_NoBackground;
+    }
+    else
+    {
+        // Floating dockspace
+        dockspace_flags &= ~ImGuiDockNodeFlags_PassthruCentralNode;
+    }
+
+    // Important: note that we proceed even if Begin() returns false (aka window is collapsed).
+    // This is because we want to keep our DockSpace() active. If a DockSpace() is inactive,
+    // all active windows docked into it will lose their parent and become undocked.
+    // We cannot preserve the docking relationship between an active window and an inactive docking, otherwise
+    // any change of dockspace/settings would lead to windows being stuck in limbo and never being visible.
+    if (!args->KeepWindowPadding)
+        ImGui::PushStyleVar(ImGuiStyleVar_WindowPadding, ImVec2(0.0f, 0.0f));
+    ImGui::Begin("Window with a DockSpace", p_open, window_flags);
+    if (!args->KeepWindowPadding)
+        ImGui::PopStyleVar();
+
+    if (args->IsFullscreen)
+        ImGui::PopStyleVar(2);
+
+    // Submit the DockSpace widget inside our window
+    // - Note that the id here is different from the one used by DockSpaceOverViewport(), so docking state won't get transfered between "Basic" and "Advanced" demos.
+    // - If we made the ShowExampleAppDockSpaceBasic() calculate its own ID and pass it to DockSpaceOverViewport() the ID could easily match.
+    ImGuiID dockspace_id = ImGui::GetID("MyDockSpace");
+    ImGui::DockSpace(dockspace_id, ImVec2(0.0f, 0.0f), dockspace_flags);
+
+    ImGui::End();
+}
+
+static void ShowExampleAppDockSpaceBasic(ImGuiDockNodeFlags flags)
+{
+    // Basic version which you can use in many apps:
+    // e.g:
+    //   ImGui::DockSpaceOverViewport();
+    // or:
+    //   ImGui::DockSpaceOverViewport(0, nullptr, ImGuiDockNodeFlags_PassthruCentralNode); // Central node will be transparent
+    // or:
+    //   ImGuiViewport* viewport = ImGui::GetMainViewport();
+    //   ImGui::DockSpaceOverViewport(0, viewport, ImGuiDockNodeFlags_None);
+
+    ImGui::DockSpaceOverViewport(0, nullptr, flags);
+}
+
+void ShowExampleAppDockSpace(bool* p_open)
+{
+    static int opt_demo_mode = 0;
+    static bool opt_demo_mode_changed = false;
+    static ImGuiDemoDockspaceArgs args;
+
+    if (opt_demo_mode == 0)
+        ShowExampleAppDockSpaceBasic(args.DockSpaceFlags);
+    else
+        ShowExampleAppDockSpaceAdvanced(&args, p_open);
+
+    // Refocus our window to minimize perceived loss of focus when changing mode (caused by the fact that each use a different window, which would not happen in a real app)
+    if (opt_demo_mode_changed)
+        ImGui::SetNextWindowFocus();
+    ImGui::Begin("Examples: Dockspace", p_open, ImGuiWindowFlags_MenuBar);
+    opt_demo_mode_changed = false;
+    opt_demo_mode_changed |= ImGui::RadioButton("Basic demo mode", &opt_demo_mode, 0);
+    opt_demo_mode_changed |= ImGui::RadioButton("Advanced demo mode", &opt_demo_mode, 1);
+
+    ImGui::SeparatorText("Options");
+
+    if ((ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_DockingEnable) == 0)
+    {
+        ShowDockingDisabledMessage();
+    }
+    else if (opt_demo_mode == 0)
+    {
+        args.DockSpaceFlags &= ImGuiDockNodeFlags_PassthruCentralNode; // Allowed flags
+        ImGui::CheckboxFlags("Flag: PassthruCentralNode", &args.DockSpaceFlags, ImGuiDockNodeFlags_PassthruCentralNode);
+    }
+    else if (opt_demo_mode == 1)
+    {
+        ImGui::Checkbox("Fullscreen", &args.IsFullscreen);
+        ImGui::Checkbox("Keep Window Padding", &args.KeepWindowPadding);
+        ImGui::SameLine();
+        HelpMarker("This is mostly exposed to facilitate understanding that a DockSpace() is _inside_ a window.");
+        ImGui::BeginDisabled(args.IsFullscreen == false);
+        ImGui::CheckboxFlags("Flag: PassthruCentralNode",      &args.DockSpaceFlags, ImGuiDockNodeFlags_PassthruCentralNode);
+        ImGui::EndDisabled();
+        ImGui::CheckboxFlags("Flag: NoDockingOverCentralNode", &args.DockSpaceFlags, ImGuiDockNodeFlags_NoDockingOverCentralNode);
+        ImGui::CheckboxFlags("Flag: NoDockingSplit",           &args.DockSpaceFlags, ImGuiDockNodeFlags_NoDockingSplit);
+        ImGui::CheckboxFlags("Flag: NoUndocking",              &args.DockSpaceFlags, ImGuiDockNodeFlags_NoUndocking);
+        ImGui::CheckboxFlags("Flag: NoResize",                 &args.DockSpaceFlags, ImGuiDockNodeFlags_NoResize);
+        ImGui::CheckboxFlags("Flag: AutoHideTabBar",           &args.DockSpaceFlags, ImGuiDockNodeFlags_AutoHideTabBar);
+    }
+
+    // Show demo options and help
+    if (ImGui::BeginMenuBar())
+    {
+        if (ImGui::BeginMenu("Help"))
+        {
+            ImGui::TextUnformatted(
+                "This demonstrates the use of ImGui::DockSpace() which allows you to manually\ncreate a docking node _within_ another window." "\n"
+                "The \"Basic\" version uses the ImGui::DockSpaceOverViewport() helper. Most applications can probably use this.");
+            ImGui::Separator();
+            ImGui::TextUnformatted("When docking is enabled, you can ALWAYS dock MOST window into another! Try it now!" "\n"
+                "- Drag from window title bar or their tab to dock/undock." "\n"
+                "- Drag from window menu button (upper-left button) to undock an entire node (all windows)." "\n"
+                "- Hold SHIFT to disable docking (if io.ConfigDockingWithShift == false, default)" "\n"
+                "- Hold SHIFT to enable docking (if io.ConfigDockingWithShift == true)");
+            ImGui::Separator();
+            ImGui::TextUnformatted("More details:"); ImGui::Bullet(); ImGui::SameLine(); ImGui::TextLinkOpenURL("Docking Wiki page", "https://github.com/ocornut/imgui/wiki/Docking");
+            ImGui::BulletText("Read comments in ShowExampleAppDockSpace()");
+            ImGui::EndMenu();
+        }
+        ImGui::EndMenuBar();
+    }
+
+    ImGui::End();
+}
+
+//-----------------------------------------------------------------------------
 // [SECTION] Example App: Documents Handling / ShowExampleAppDocuments()
 //-----------------------------------------------------------------------------
 
@@ -10344,11 +10619,25 @@
     static ExampleAppDocuments app;
 
     // Options
+    enum Target
+    {
+        Target_None,
+        Target_Tab,                 // Create documents as local tab into a local tab bar
+        Target_DockSpaceAndWindow   // Create documents as regular windows, and create an embedded dockspace
+    };
+    static Target opt_target = Target_Tab;
     static bool opt_reorderable = true;
     static ImGuiTabBarFlags opt_fitting_flags = ImGuiTabBarFlags_FittingPolicyDefault_;
 
+    // When (opt_target == Target_DockSpaceAndWindow) there is the possibily that one of our child Document window (e.g. "Eggplant")
+    // that we emit gets docked into the same spot as the parent window ("Example: Documents").
+    // This would create a problematic feedback loop because selecting the "Eggplant" tab would make the "Example: Documents" tab
+    // not visible, which in turn would stop submitting the "Eggplant" window.
+    // We avoid this problem by submitting our documents window even if our parent window is not currently visible.
+    // Another solution may be to make the "Example: Documents" window use the ImGuiWindowFlags_NoDocking.
+
     bool window_contents_visible = ImGui::Begin("Example: Documents", p_open, ImGuiWindowFlags_MenuBar);
-    if (!window_contents_visible)
+    if (!window_contents_visible && opt_target != Target_DockSpaceAndWindow)
     {
         ImGui::End();
         return;
@@ -10392,6 +10681,12 @@
                 doc.DoForceClose();
         ImGui::PopID();
     }
+    ImGui::PushItemWidth(ImGui::GetFontSize() * 12);
+    ImGui::Combo("Output", (int*)&opt_target, "None\0TabBar+Tabs\0DockSpace+Window\0");
+    ImGui::PopItemWidth();
+    bool redock_all = false;
+    if (opt_target == Target_Tab)                { ImGui::SameLine(); ImGui::Checkbox("Reorderable Tabs", &opt_reorderable); }
+    if (opt_target == Target_DockSpaceAndWindow) { ImGui::SameLine(); redock_all = ImGui::Button("Redock all"); }
 
     ImGui::Separator();
 
@@ -10405,7 +10700,8 @@
     //   hole for one-frame, both in the tab-bar and in tab-contents when closing a tab/window.
     //   The rarely used SetTabItemClosed() function is a way to notify of programmatic closure to avoid the one-frame hole.
 
-    // Submit Tab Bar and Tabs
+    // Tabs
+    if (opt_target == Target_Tab)
     {
         ImGuiTabBarFlags tab_bar_flags = (opt_fitting_flags) | (opt_reorderable ? ImGuiTabBarFlags_Reorderable : 0);
         tab_bar_flags |= ImGuiTabBarFlags_DrawSelectedOverline;
@@ -10448,6 +10744,53 @@
             ImGui::EndTabBar();
         }
     }
+    else if (opt_target == Target_DockSpaceAndWindow)
+    {
+        if (ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_DockingEnable)
+        {
+            app.NotifyOfDocumentsClosedElsewhere();
+
+            // Create a DockSpace node where any window can be docked
+            ImGuiID dockspace_id = ImGui::GetID("MyDockSpace");
+            ImGui::DockSpace(dockspace_id);
+
+            // Create Windows
+            for (int doc_n = 0; doc_n < app.Documents.Size; doc_n++)
+            {
+                MyDocument* doc = &app.Documents[doc_n];
+                if (!doc->Open)
+                    continue;
+
+                ImGui::SetNextWindowDockID(dockspace_id, redock_all ? ImGuiCond_Always : ImGuiCond_FirstUseEver);
+                ImGuiWindowFlags window_flags = (doc->Dirty ? ImGuiWindowFlags_UnsavedDocument : 0);
+                bool visible = ImGui::Begin(doc->Name, &doc->Open, window_flags);
+
+                // Cancel attempt to close when unsaved add to save queue so we can display a popup.
+                if (!doc->Open && doc->Dirty)
+                {
+                    doc->Open = true;
+                    app.CloseQueue.push_back(doc);
+                }
+
+                app.DisplayDocContextMenu(doc);
+                if (visible)
+                    app.DisplayDocContents(doc);
+
+                ImGui::End();
+            }
+        }
+        else
+        {
+            ShowDockingDisabledMessage();
+        }
+    }
+
+    // Early out other contents
+    if (!window_contents_visible)
+    {
+        ImGui::End();
+        return;
+    }
 
     // Display renaming UI
     if (app.RenamingDoc != NULL)

diff --git a/imgui_draw.cpp b/imgui_draw.cpp
index 20a24a9..9c0af09 100644
--- a/imgui_draw.cpp
+++ b/imgui_draw.cpp

@@ -230,6 +230,8 @@
     colors[ImGuiCol_TabDimmed]              = ImLerp(colors[ImGuiCol_Tab],          colors[ImGuiCol_TitleBg], 0.80f);
     colors[ImGuiCol_TabDimmedSelected]      = ImLerp(colors[ImGuiCol_TabSelected],  colors[ImGuiCol_TitleBg], 0.40f);
     colors[ImGuiCol_TabDimmedSelectedOverline] = ImVec4(0.50f, 0.50f, 0.50f, 0.00f);
+    colors[ImGuiCol_DockingPreview]         = colors[ImGuiCol_HeaderActive] * ImVec4(1.0f, 1.0f, 1.0f, 0.7f);
+    colors[ImGuiCol_DockingEmptyBg]         = ImVec4(0.20f, 0.20f, 0.20f, 1.00f);
     colors[ImGuiCol_PlotLines]              = ImVec4(0.61f, 0.61f, 0.61f, 1.00f);
     colors[ImGuiCol_PlotLinesHovered]       = ImVec4(1.00f, 0.43f, 0.35f, 1.00f);
     colors[ImGuiCol_PlotHistogram]          = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
@@ -297,6 +299,8 @@
     colors[ImGuiCol_TabDimmed]              = ImLerp(colors[ImGuiCol_Tab],          colors[ImGuiCol_TitleBg], 0.80f);
     colors[ImGuiCol_TabDimmedSelected]      = ImLerp(colors[ImGuiCol_TabSelected],  colors[ImGuiCol_TitleBg], 0.40f);
     colors[ImGuiCol_TabDimmedSelectedOverline] = ImVec4(0.53f, 0.53f, 0.87f, 0.00f);
+    colors[ImGuiCol_DockingPreview]         = colors[ImGuiCol_Header] * ImVec4(1.0f, 1.0f, 1.0f, 0.7f);
+    colors[ImGuiCol_DockingEmptyBg]         = ImVec4(0.20f, 0.20f, 0.20f, 1.00f);
     colors[ImGuiCol_PlotLines]              = ImVec4(1.00f, 1.00f, 1.00f, 1.00f);
     colors[ImGuiCol_PlotLinesHovered]       = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
     colors[ImGuiCol_PlotHistogram]          = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
@@ -365,6 +369,8 @@
     colors[ImGuiCol_TabDimmed]              = ImLerp(colors[ImGuiCol_Tab],          colors[ImGuiCol_TitleBg], 0.80f);
     colors[ImGuiCol_TabDimmedSelected]      = ImLerp(colors[ImGuiCol_TabSelected],  colors[ImGuiCol_TitleBg], 0.40f);
     colors[ImGuiCol_TabDimmedSelectedOverline] = ImVec4(0.26f, 0.59f, 1.00f, 0.00f);
+    colors[ImGuiCol_DockingPreview]         = colors[ImGuiCol_Header] * ImVec4(1.0f, 1.0f, 1.0f, 0.7f);
+    colors[ImGuiCol_DockingEmptyBg]         = ImVec4(0.20f, 0.20f, 0.20f, 1.00f);
     colors[ImGuiCol_PlotLines]              = ImVec4(0.39f, 0.39f, 0.39f, 1.00f);
     colors[ImGuiCol_PlotLinesHovered]       = ImVec4(1.00f, 0.43f, 0.35f, 1.00f);
     colors[ImGuiCol_PlotHistogram]          = ImVec4(0.90f, 0.70f, 0.00f, 1.00f);
@@ -5953,6 +5959,7 @@
 // - RenderArrow()
 // - RenderBullet()
 // - RenderCheckMark()
+// - RenderArrowDockMenu()
 // - RenderArrowPointingAt()
 // - RenderRectFilledInRangeH()
 // - RenderRectFilledWithHole()
@@ -6028,6 +6035,14 @@
     }
 }
 
+// This is less wide than RenderArrow() and we use in dock nodes instead of the regular RenderArrow() to denote a change of functionality,
+// and because the saved space means that the left-most tab label can stay at exactly the same position as the label of a loose window.
+void ImGui::RenderArrowDockMenu(ImDrawList* draw_list, ImVec2 p_min, float sz, ImU32 col)
+{
+    draw_list->AddRectFilled(p_min + ImVec2(sz * 0.20f, sz * 0.15f), p_min + ImVec2(sz * 0.80f, sz * 0.30f), col);
+    RenderArrowPointingAt(draw_list, p_min + ImVec2(sz * 0.50f, sz * 0.85f), ImVec2(sz * 0.30f, sz * 0.40f), ImGuiDir_Down, col);
+}
+
 static inline float ImAcos01(float x)
 {
     if (x <= 0.0f) return IM_PI * 0.5f;

diff --git a/imgui_internal.h b/imgui_internal.h
index c574575..2a71e0f 100644
--- a/imgui_internal.h
+++ b/imgui_internal.h

@@ -153,6 +153,10 @@
 struct ImGuiContextHook;            // Hook for extensions like ImGuiTestEngine
 struct ImGuiDataTypeInfo;           // Type information associated to a ImGuiDataType enum
 struct ImGuiDeactivatedItemData;    // Data for IsItemDeactivated()/IsItemDeactivatedAfterEdit() function.
+struct ImGuiDockContext;            // Docking system context
+struct ImGuiDockRequest;            // Docking system dock/undock queued request
+struct ImGuiDockNode;               // Docking system node (hold a list of Windows OR two child dock nodes)
+struct ImGuiDockNodeSettings;       // Storage for a dock node in .ini file (we preserve those even if the associated dock node isn't active during the session)
 struct ImGuiErrorRecoveryState;     // Storage of stack sizes for error handling and recovery
 struct ImGuiGroupData;              // Stacked storage data for BeginGroup()/EndGroup()
 struct ImGuiInputTextState;         // Internal state of the currently focused/edited text input box
@@ -185,12 +189,14 @@
 struct ImGuiTypingSelectState;      // Storage for GetTypingSelectRequest()
 struct ImGuiTypingSelectRequest;    // Storage for GetTypingSelectRequest() (aimed to be public)
 struct ImGuiWindow;                 // Storage for one window
+struct ImGuiWindowDockStyle;        // Storage for window-style data which needs to be stored for docking purpose
 struct ImGuiWindowTempData;         // Temporary storage for one window (that's the data which in theory we could ditch at the end of the frame, in practice we currently keep it for each window)
 struct ImGuiWindowSettings;         // Storage for a window .ini settings (we keep one of those even if the actual window wasn't instanced during this session)
 
 // Enumerations
 // Use your programming IDE "Go to definition" facility on the names of the center columns to find the actual flags/enum lists.
 enum ImGuiLocKey : int;                 // -> enum ImGuiLocKey              // Enum: a localization entry for translation.
+typedef int ImGuiDataAuthority;         // -> enum ImGuiDataAuthority_      // Enum: for storing the source authority (dock node vs window) of a field
 typedef int ImGuiLayoutType;            // -> enum ImGuiLayoutType_         // Enum: Horizontal or vertical
 
 // Flags
@@ -230,6 +236,9 @@
 // [SECTION] Macros
 //-----------------------------------------------------------------------------
 
+// Internal Drag and Drop payload types. String starting with '_' are reserved for Dear ImGui.
+#define IMGUI_PAYLOAD_TYPE_WINDOW       "_IMWINDOW"     // Payload == ImGuiWindow*
+
 // Debug Printing Into TTY
 // (since IMGUI_VERSION_NUM >= 18729: IMGUI_DEBUG_LOG was reworked into IMGUI_DEBUG_PRINTF (and removed framecount from it). If you were using a #define IMGUI_DEBUG_LOG please rename)
 #ifndef IMGUI_DEBUG_PRINTF
@@ -251,6 +260,8 @@
 #define IMGUI_DEBUG_LOG_IO(...)         do { if (g.DebugLogFlags & ImGuiDebugLogFlags_EventIO)          IMGUI_DEBUG_LOG(__VA_ARGS__); } while (0)
 #define IMGUI_DEBUG_LOG_FONT(...)       do { ImGuiContext* g2 = GImGui; if (g2 && g2->DebugLogFlags & ImGuiDebugLogFlags_EventFont) IMGUI_DEBUG_LOG(__VA_ARGS__); } while (0) // Called from ImFontAtlas function which may operate without a context.
 #define IMGUI_DEBUG_LOG_INPUTROUTING(...) do{if (g.DebugLogFlags & ImGuiDebugLogFlags_EventInputRouting)IMGUI_DEBUG_LOG(__VA_ARGS__); } while (0)
+#define IMGUI_DEBUG_LOG_DOCKING(...)    do { if (g.DebugLogFlags & ImGuiDebugLogFlags_EventDocking)     IMGUI_DEBUG_LOG(__VA_ARGS__); } while (0)
+#define IMGUI_DEBUG_LOG_VIEWPORT(...)   do { if (g.DebugLogFlags & ImGuiDebugLogFlags_EventViewport)    IMGUI_DEBUG_LOG(__VA_ARGS__); } while (0)
 
 // Static Asserts
 #define IM_STATIC_ASSERT(_COND)         static_assert(_COND, "")
@@ -1014,7 +1025,7 @@
 enum ImGuiHoveredFlagsPrivate_
 {
     ImGuiHoveredFlags_DelayMask_                    = ImGuiHoveredFlags_DelayNone | ImGuiHoveredFlags_DelayShort | ImGuiHoveredFlags_DelayNormal | ImGuiHoveredFlags_NoSharedDelay,
-    ImGuiHoveredFlags_AllowedMaskForIsWindowHovered = ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_RootWindow | ImGuiHoveredFlags_AnyWindow | ImGuiHoveredFlags_NoPopupHierarchy | ImGuiHoveredFlags_AllowWhenBlockedByPopup | ImGuiHoveredFlags_AllowWhenBlockedByActiveItem | ImGuiHoveredFlags_ForTooltip | ImGuiHoveredFlags_Stationary,
+    ImGuiHoveredFlags_AllowedMaskForIsWindowHovered = ImGuiHoveredFlags_ChildWindows | ImGuiHoveredFlags_RootWindow | ImGuiHoveredFlags_AnyWindow | ImGuiHoveredFlags_NoPopupHierarchy | ImGuiHoveredFlags_DockHierarchy | ImGuiHoveredFlags_AllowWhenBlockedByPopup | ImGuiHoveredFlags_AllowWhenBlockedByActiveItem | ImGuiHoveredFlags_ForTooltip | ImGuiHoveredFlags_Stationary,
     ImGuiHoveredFlags_AllowedMaskForIsItemHovered   = ImGuiHoveredFlags_AllowWhenBlockedByPopup | ImGuiHoveredFlags_AllowWhenBlockedByActiveItem | ImGuiHoveredFlags_AllowWhenOverlapped | ImGuiHoveredFlags_AllowWhenDisabled | ImGuiHoveredFlags_NoNavOverride | ImGuiHoveredFlags_ForTooltip | ImGuiHoveredFlags_Stationary | ImGuiHoveredFlags_DelayMask_,
 };
 
@@ -1310,6 +1321,9 @@
     ImGuiNextWindowDataFlags_HasWindowFlags     = 1 << 8,
     ImGuiNextWindowDataFlags_HasChildFlags      = 1 << 9,
     ImGuiNextWindowDataFlags_HasRefreshPolicy   = 1 << 10,
+    ImGuiNextWindowDataFlags_HasViewport        = 1 << 11,
+    ImGuiNextWindowDataFlags_HasDock            = 1 << 12,
+    ImGuiNextWindowDataFlags_HasWindowClass     = 1 << 13,
 };
 
 // Storage for SetNexWindow** functions
@@ -1321,6 +1335,7 @@
     ImGuiCond                   PosCond;
     ImGuiCond                   SizeCond;
     ImGuiCond                   CollapsedCond;
+    ImGuiCond                   DockCond;
     ImVec2                      PosVal;
     ImVec2                      PosPivotVal;
     ImVec2                      SizeVal;
@@ -1328,11 +1343,15 @@
     ImVec2                      ScrollVal;
     ImGuiWindowFlags            WindowFlags;            // Only honored by BeginTable()
     ImGuiChildFlags             ChildFlags;
+    bool                        PosUndock;
     bool                        CollapsedVal;
     ImRect                      SizeConstraintRect;
     ImGuiSizeCallback           SizeCallback;
     void*                       SizeCallbackUserData;
     float                       BgAlphaVal;             // Override background alpha
+    ImGuiID                     ViewportId;
+    ImGuiID                     DockId;
+    ImGuiWindowClass            WindowClass;
     ImVec2                      MenuBarOffsetMinVal;    // (Always on) This is not exposed publicly, so we don't clear it and it doesn't have a corresponding flag (could we? for consistency?)
     ImGuiWindowRefreshFlags     RefreshFlagsVal;
 
@@ -1517,6 +1536,7 @@
     ImGuiInputEventType_MousePos,
     ImGuiInputEventType_MouseWheel,
     ImGuiInputEventType_MouseButton,
+    ImGuiInputEventType_MouseViewport,
     ImGuiInputEventType_Key,
     ImGuiInputEventType_Text,
     ImGuiInputEventType_Focus,
@@ -1537,6 +1557,7 @@
 struct ImGuiInputEventMousePos      { float PosX, PosY; ImGuiMouseSource MouseSource; };
 struct ImGuiInputEventMouseWheel    { float WheelX, WheelY; ImGuiMouseSource MouseSource; };
 struct ImGuiInputEventMouseButton   { int Button; bool Down; ImGuiMouseSource MouseSource; };
+struct ImGuiInputEventMouseViewport { ImGuiID HoveredViewportID; };
 struct ImGuiInputEventKey           { ImGuiKey Key; bool Down; float AnalogValue; };
 struct ImGuiInputEventText          { unsigned int Char; };
 struct ImGuiInputEventAppFocused    { bool Focused; };
@@ -1551,6 +1572,7 @@
         ImGuiInputEventMousePos     MousePos;       // if Type == ImGuiInputEventType_MousePos
         ImGuiInputEventMouseWheel   MouseWheel;     // if Type == ImGuiInputEventType_MouseWheel
         ImGuiInputEventMouseButton  MouseButton;    // if Type == ImGuiInputEventType_MouseButton
+        ImGuiInputEventMouseViewport MouseViewport; // if Type == ImGuiInputEventType_MouseViewport
         ImGuiInputEventKey          Key;            // if Type == ImGuiInputEventType_Key
         ImGuiInputEventText         Text;           // if Type == ImGuiInputEventType_Text
         ImGuiInputEventAppFocused   AppFocused;     // if Type == ImGuiInputEventType_Focus
@@ -1946,8 +1968,156 @@
 // [SECTION] Docking support
 //-----------------------------------------------------------------------------
 
+#define DOCKING_HOST_DRAW_CHANNEL_BG 0  // Dock host: background fill
+#define DOCKING_HOST_DRAW_CHANNEL_FG 1  // Dock host: decorations and contents
+
 #ifdef IMGUI_HAS_DOCK
-// <this is filled in 'docking' branch>
+
+// Extend ImGuiDockNodeFlags_
+enum ImGuiDockNodeFlagsPrivate_
+{
+    // [Internal]
+    ImGuiDockNodeFlags_DockSpace                = 1 << 10,  // Saved // A dockspace is a node that occupy space within an existing user window. Otherwise the node is floating and create its own window.
+    ImGuiDockNodeFlags_CentralNode              = 1 << 11,  // Saved // The central node has 2 main properties: stay visible when empty, only use "remaining" spaces from its neighbor.
+    ImGuiDockNodeFlags_NoTabBar                 = 1 << 12,  // Saved // Tab bar is completely unavailable. No triangle in the corner to enable it back.
+    ImGuiDockNodeFlags_HiddenTabBar             = 1 << 13,  // Saved // Tab bar is hidden, with a triangle in the corner to show it again (NB: actual tab-bar instance may be destroyed as this is only used for single-window tab bar)
+    ImGuiDockNodeFlags_NoWindowMenuButton       = 1 << 14,  // Saved // Disable window/docking menu (that one that appears instead of the collapse button)
+    ImGuiDockNodeFlags_NoCloseButton            = 1 << 15,  // Saved // Disable close button
+    ImGuiDockNodeFlags_NoResizeX                = 1 << 16,  //       //
+    ImGuiDockNodeFlags_NoResizeY                = 1 << 17,  //       //
+    ImGuiDockNodeFlags_DockedWindowsInFocusRoute= 1 << 18,  //       // Any docked window will be automatically be focus-route chained (window->ParentWindowForFocusRoute set to this) so Shortcut() in this window can run when any docked window is focused.
+
+    // Disable docking/undocking actions in this dockspace or individual node (existing docked nodes will be preserved)
+    // Those are not exposed in public because the desirable sharing/inheriting/copy-flag-on-split behaviors are quite difficult to design and understand.
+    // The two public flags ImGuiDockNodeFlags_NoDockingOverCentralNode/ImGuiDockNodeFlags_NoDockingSplit don't have those issues.
+    ImGuiDockNodeFlags_NoDockingSplitOther      = 1 << 19,  //       // Disable this node from splitting other windows/nodes.
+    ImGuiDockNodeFlags_NoDockingOverMe          = 1 << 20,  //       // Disable other windows/nodes from being docked over this node.
+    ImGuiDockNodeFlags_NoDockingOverOther       = 1 << 21,  //       // Disable this node from being docked over another window or non-empty node.
+    ImGuiDockNodeFlags_NoDockingOverEmpty       = 1 << 22,  //       // Disable this node from being docked over an empty node (e.g. DockSpace with no other windows)
+    ImGuiDockNodeFlags_NoDocking                = ImGuiDockNodeFlags_NoDockingOverMe | ImGuiDockNodeFlags_NoDockingOverOther | ImGuiDockNodeFlags_NoDockingOverEmpty | ImGuiDockNodeFlags_NoDockingSplit | ImGuiDockNodeFlags_NoDockingSplitOther,
+
+    // Masks
+    ImGuiDockNodeFlags_SharedFlagsInheritMask_  = ~0,
+    ImGuiDockNodeFlags_NoResizeFlagsMask_       = (int)ImGuiDockNodeFlags_NoResize | ImGuiDockNodeFlags_NoResizeX | ImGuiDockNodeFlags_NoResizeY,
+
+    // When splitting, those local flags are moved to the inheriting child, never duplicated
+    ImGuiDockNodeFlags_LocalFlagsTransferMask_  = (int)ImGuiDockNodeFlags_NoDockingSplit | ImGuiDockNodeFlags_NoResizeFlagsMask_ | (int)ImGuiDockNodeFlags_AutoHideTabBar | ImGuiDockNodeFlags_CentralNode | ImGuiDockNodeFlags_NoTabBar | ImGuiDockNodeFlags_HiddenTabBar | ImGuiDockNodeFlags_NoWindowMenuButton | ImGuiDockNodeFlags_NoCloseButton,
+    ImGuiDockNodeFlags_SavedFlagsMask_          = ImGuiDockNodeFlags_NoResizeFlagsMask_ | ImGuiDockNodeFlags_DockSpace | ImGuiDockNodeFlags_CentralNode | ImGuiDockNodeFlags_NoTabBar | ImGuiDockNodeFlags_HiddenTabBar | ImGuiDockNodeFlags_NoWindowMenuButton | ImGuiDockNodeFlags_NoCloseButton,
+};
+
+// Store the source authority (dock node vs window) of a field
+enum ImGuiDataAuthority_
+{
+    ImGuiDataAuthority_Auto,
+    ImGuiDataAuthority_DockNode,
+    ImGuiDataAuthority_Window,
+};
+
+enum ImGuiDockNodeState
+{
+    ImGuiDockNodeState_Unknown,
+    ImGuiDockNodeState_HostWindowHiddenBecauseSingleWindow,
+    ImGuiDockNodeState_HostWindowHiddenBecauseWindowsAreResizing,
+    ImGuiDockNodeState_HostWindowVisible,
+};
+
+// sizeof() 156~192
+struct IMGUI_API ImGuiDockNode
+{
+    ImGuiID                 ID;
+    ImGuiDockNodeFlags      SharedFlags;                // (Write) Flags shared by all nodes of a same dockspace hierarchy (inherited from the root node)
+    ImGuiDockNodeFlags      LocalFlags;                 // (Write) Flags specific to this node
+    ImGuiDockNodeFlags      LocalFlagsInWindows;        // (Write) Flags specific to this node, applied from windows
+    ImGuiDockNodeFlags      MergedFlags;                // (Read)  Effective flags (== SharedFlags | LocalFlagsInNode | LocalFlagsInWindows)
+    ImGuiDockNodeState      State;
+    ImGuiDockNode*          ParentNode;
+    ImGuiDockNode*          ChildNodes[2];              // [Split node only] Child nodes (left/right or top/bottom). Consider switching to an array.
+    ImVector<ImGuiWindow*>  Windows;                    // Note: unordered list! Iterate TabBar->Tabs for user-order.
+    ImGuiTabBar*            TabBar;
+    ImVec2                  Pos;                        // Current position
+    ImVec2                  Size;                       // Current size
+    ImVec2                  SizeRef;                    // [Split node only] Last explicitly written-to size (overridden when using a splitter affecting the node), used to calculate Size.
+    ImGuiAxis               SplitAxis;                  // [Split node only] Split axis (X or Y)
+    ImGuiWindowClass        WindowClass;                // [Root node only]
+    ImU32                   LastBgColor;
+
+    ImGuiWindow*            HostWindow;
+    ImGuiWindow*            VisibleWindow;              // Generally point to window which is ID is == SelectedTabID, but when CTRL+Tabbing this can be a different window.
+    ImGuiDockNode*          CentralNode;                // [Root node only] Pointer to central node.
+    ImGuiDockNode*          OnlyNodeWithWindows;        // [Root node only] Set when there is a single visible node within the hierarchy.
+    int                     CountNodeWithWindows;       // [Root node only]
+    int                     LastFrameAlive;             // Last frame number the node was updated or kept alive explicitly with DockSpace() + ImGuiDockNodeFlags_KeepAliveOnly
+    int                     LastFrameActive;            // Last frame number the node was updated.
+    int                     LastFrameFocused;           // Last frame number the node was focused.
+    ImGuiID                 LastFocusedNodeId;          // [Root node only] Which of our child docking node (any ancestor in the hierarchy) was last focused.
+    ImGuiID                 SelectedTabId;              // [Leaf node only] Which of our tab/window is selected.
+    ImGuiID                 WantCloseTabId;             // [Leaf node only] Set when closing a specific tab/window.
+    ImGuiID                 RefViewportId;              // Reference viewport ID from visible window when HostWindow == NULL.
+    ImGuiDataAuthority      AuthorityForPos         :3;
+    ImGuiDataAuthority      AuthorityForSize        :3;
+    ImGuiDataAuthority      AuthorityForViewport    :3;
+    bool                    IsVisible               :1; // Set to false when the node is hidden (usually disabled as it has no active window)
+    bool                    IsFocused               :1;
+    bool                    IsBgDrawnThisFrame      :1;
+    bool                    HasCloseButton          :1; // Provide space for a close button (if any of the docked window has one). Note that button may be hidden on window without one.
+    bool                    HasWindowMenuButton     :1;
+    bool                    HasCentralNodeChild     :1;
+    bool                    WantCloseAll            :1; // Set when closing all tabs at once.
+    bool                    WantLockSizeOnce        :1;
+    bool                    WantMouseMove           :1; // After a node extraction we need to transition toward moving the newly created host window
+    bool                    WantHiddenTabBarUpdate  :1;
+    bool                    WantHiddenTabBarToggle  :1;
+
+    ImGuiDockNode(ImGuiID id);
+    ~ImGuiDockNode();
+    bool                    IsRootNode() const      { return ParentNode == NULL; }
+    bool                    IsDockSpace() const     { return (MergedFlags & ImGuiDockNodeFlags_DockSpace) != 0; }
+    bool                    IsFloatingNode() const  { return ParentNode == NULL && (MergedFlags & ImGuiDockNodeFlags_DockSpace) == 0; }
+    bool                    IsCentralNode() const   { return (MergedFlags & ImGuiDockNodeFlags_CentralNode) != 0; }
+    bool                    IsHiddenTabBar() const  { return (MergedFlags & ImGuiDockNodeFlags_HiddenTabBar) != 0; } // Hidden tab bar can be shown back by clicking the small triangle
+    bool                    IsNoTabBar() const      { return (MergedFlags & ImGuiDockNodeFlags_NoTabBar) != 0; }     // Never show a tab bar
+    bool                    IsSplitNode() const     { return ChildNodes[0] != NULL; }
+    bool                    IsLeafNode() const      { return ChildNodes[0] == NULL; }
+    bool                    IsEmpty() const         { return ChildNodes[0] == NULL && Windows.Size == 0; }
+    ImRect                  Rect() const            { return ImRect(Pos.x, Pos.y, Pos.x + Size.x, Pos.y + Size.y); }
+
+    void                    SetLocalFlags(ImGuiDockNodeFlags flags) { LocalFlags = flags; UpdateMergedFlags(); }
+    void                    UpdateMergedFlags()     { MergedFlags = SharedFlags | LocalFlags | LocalFlagsInWindows; }
+};
+
+// List of colors that are stored at the time of Begin() into Docked Windows.
+// We currently store the packed colors in a simple array window->DockStyle.Colors[].
+// A better solution may involve appending into a log of colors in ImGuiContext + store offsets into those arrays in ImGuiWindow,
+// but it would be more complex as we'd need to double-buffer both as e.g. drop target may refer to window from last frame.
+enum ImGuiWindowDockStyleCol
+{
+    ImGuiWindowDockStyleCol_Text,
+    ImGuiWindowDockStyleCol_TabHovered,
+    ImGuiWindowDockStyleCol_TabFocused,
+    ImGuiWindowDockStyleCol_TabSelected,
+    ImGuiWindowDockStyleCol_TabSelectedOverline,
+    ImGuiWindowDockStyleCol_TabDimmed,
+    ImGuiWindowDockStyleCol_TabDimmedSelected,
+    ImGuiWindowDockStyleCol_TabDimmedSelectedOverline,
+    ImGuiWindowDockStyleCol_UnsavedMarker,
+    ImGuiWindowDockStyleCol_COUNT
+};
+
+// We don't store style.Alpha: dock_node->LastBgColor embeds it and otherwise it would only affect the docking tab, which intuitively I would say we don't want to.
+struct ImGuiWindowDockStyle
+{
+    ImU32 Colors[ImGuiWindowDockStyleCol_COUNT];
+};
+
+struct ImGuiDockContext
+{
+    ImGuiStorage                    Nodes;          // Map ID -> ImGuiDockNode*: Active nodes
+    ImVector<ImGuiDockRequest>      Requests;
+    ImVector<ImGuiDockNodeSettings> NodesSettings;
+    bool                            WantFullRebuild;
+    ImGuiDockContext()              { memset((void*)this, 0, sizeof(*this)); }
+};
+
 #endif // #ifdef IMGUI_HAS_DOCK
 
 //-----------------------------------------------------------------------------
@@ -1958,10 +2128,24 @@
 // Every instance of ImGuiViewport is in fact a ImGuiViewportP.
 struct ImGuiViewportP : public ImGuiViewport
 {
+    ImGuiWindow*        Window;                 // Set when the viewport is owned by a window (and ImGuiViewportFlags_CanHostOtherWindows is NOT set)
+    int                 Idx;
+    int                 LastFrameActive;        // Last frame number this viewport was activated by a window
+    int                 LastFocusedStampCount;  // Last stamp number from when a window hosted by this viewport was focused (by comparing this value between two viewport we have an implicit viewport z-order we use as fallback)
+    ImGuiID             LastNameHash;
+    ImVec2              LastPos;
+    ImVec2              LastSize;
+    float               Alpha;                  // Window opacity (when dragging dockable windows/viewports we make them transparent)
+    float               LastAlpha;
+    bool                LastFocusedHadNavWindow;// Instead of maintaining a LastFocusedWindow (which may harder to correctly maintain), we merely store weither NavWindow != NULL last time the viewport was focused.
+    short               PlatformMonitor;
     int                 BgFgDrawListsLastFrame[2]; // Last frame number the background (0) and foreground (1) draw lists were used
     ImDrawList*         BgFgDrawLists[2];       // Convenience background (0) and foreground (1) draw lists. We use them to draw software mouser cursor when io.MouseDrawCursor is set and to draw most debug overlays.
     ImDrawData          DrawDataP;
     ImDrawDataBuilder   DrawDataBuilder;        // Temporary data while building final ImDrawData
+    ImVec2              LastPlatformPos;
+    ImVec2              LastPlatformSize;
+    ImVec2              LastRendererSize;
 
     // Per-viewport work area
     // - Insets are >= 0.0f values, distance from viewport corners to work area.
@@ -1972,8 +2156,9 @@
     ImVec2              BuildWorkInsetMin;      // Work Area inset accumulator for current frame, to become next frame's WorkInset
     ImVec2              BuildWorkInsetMax;      // "
 
-    ImGuiViewportP()    { BgFgDrawListsLastFrame[0] = BgFgDrawListsLastFrame[1] = -1; BgFgDrawLists[0] = BgFgDrawLists[1] = NULL; }
-    ~ImGuiViewportP()   { if (BgFgDrawLists[0]) IM_DELETE(BgFgDrawLists[0]); if (BgFgDrawLists[1]) IM_DELETE(BgFgDrawLists[1]); }
+    ImGuiViewportP()                    { Window = NULL; Idx = -1; LastFrameActive = BgFgDrawListsLastFrame[0] = BgFgDrawListsLastFrame[1] = LastFocusedStampCount = -1; LastNameHash = 0; Alpha = LastAlpha = 1.0f; LastFocusedHadNavWindow = false; PlatformMonitor = -1; BgFgDrawLists[0] = BgFgDrawLists[1] = NULL; LastPlatformPos = LastPlatformSize = LastRendererSize = ImVec2(FLT_MAX, FLT_MAX); }
+    ~ImGuiViewportP()                   { if (BgFgDrawLists[0]) IM_DELETE(BgFgDrawLists[0]); if (BgFgDrawLists[1]) IM_DELETE(BgFgDrawLists[1]); }
+    void    ClearRequestFlags()         { PlatformRequestClose = PlatformRequestMove = PlatformRequestResize = false; }
 
     // Calculate work rect pos/size given a set of offset (we have 1 pair of offset for rect locked from last frame data, and 1 pair for currently building rect)
     ImVec2  CalcWorkRectPos(const ImVec2& inset_min) const                           { return ImVec2(Pos.x + inset_min.x, Pos.y + inset_min.y); }
@@ -1996,14 +2181,19 @@
 struct ImGuiWindowSettings
 {
     ImGuiID     ID;
-    ImVec2ih    Pos;
+    ImVec2ih    Pos;            // NB: Settings position are stored RELATIVE to the viewport! Whereas runtime ones are absolute positions.
     ImVec2ih    Size;
+    ImVec2ih    ViewportPos;
+    ImGuiID     ViewportId;
+    ImGuiID     DockId;         // ID of last known DockNode (even if the DockNode is invisible because it has only 1 active window), or 0 if none.
+    ImGuiID     ClassId;        // ID of window class if specified
+    short       DockOrder;      // Order of the last time the window was visible within its DockNode. This is used to reorder windows that are reappearing on the same frame. Same value between windows that were active and windows that were none are possible.
     bool        Collapsed;
     bool        IsChild;
     bool        WantApply;      // Set when loaded from .ini data (to enable merging/loading .ini data into an already running context)
     bool        WantDelete;     // Set to invalidate/delete the settings entry
 
-    ImGuiWindowSettings()       { memset((void*)this, 0, sizeof(*this)); }
+    ImGuiWindowSettings()       { memset((void*)this, 0, sizeof(*this)); DockOrder = -1; }
     char* GetName()             { return (char*)(this + 1); }
 };
 
@@ -2039,6 +2229,9 @@
     ImGuiLocKey_WindowingUntitled,
     ImGuiLocKey_OpenLink_s,
     ImGuiLocKey_CopyLink,
+    ImGuiLocKey_DockingHideTabBar,
+    ImGuiLocKey_DockingHoldShiftToDock,
+    ImGuiLocKey_DockingDragToUndockOrMoveNode,
     ImGuiLocKey_COUNT
 };
 
@@ -2085,8 +2278,8 @@
     ImGuiDebugLogFlags_EventIO              = 1 << 7,
     ImGuiDebugLogFlags_EventFont            = 1 << 8,
     ImGuiDebugLogFlags_EventInputRouting    = 1 << 9,
-    ImGuiDebugLogFlags_EventDocking         = 1 << 10,  // Unused in this branch
-    ImGuiDebugLogFlags_EventViewport        = 1 << 11,  // Unused in this branch
+    ImGuiDebugLogFlags_EventDocking         = 1 << 10,
+    ImGuiDebugLogFlags_EventViewport        = 1 << 11,
 
     ImGuiDebugLogFlags_EventMask_           = ImGuiDebugLogFlags_EventError | ImGuiDebugLogFlags_EventActiveId | ImGuiDebugLogFlags_EventFocus | ImGuiDebugLogFlags_EventPopup | ImGuiDebugLogFlags_EventNav | ImGuiDebugLogFlags_EventClipper | ImGuiDebugLogFlags_EventSelection | ImGuiDebugLogFlags_EventIO | ImGuiDebugLogFlags_EventFont | ImGuiDebugLogFlags_EventInputRouting | ImGuiDebugLogFlags_EventDocking | ImGuiDebugLogFlags_EventViewport,
     ImGuiDebugLogFlags_OutputToTTY          = 1 << 20,  // Also send output to TTY
@@ -2122,6 +2315,7 @@
     bool        ShowDrawCmdBoundingBoxes = true;
     bool        ShowTextEncodingViewer = false;
     bool        ShowTextureUsedRect = false;
+    bool        ShowDockingNodes = false;
     int         ShowWindowsRectsType = -1;
     int         ShowTablesRectsType = -1;
     int         HighlightMonitorIdx = -1;
@@ -2194,12 +2388,15 @@
     bool                    TestEngineHookItems;                // Will call test engine hooks: ImGuiTestEngineHook_ItemAdd(), ImGuiTestEngineHook_ItemInfo(), ImGuiTestEngineHook_Log()
     int                     FrameCount;
     int                     FrameCountEnded;
+    int                     FrameCountPlatformEnded;
     int                     FrameCountRendered;
     double                  Time;
     char                    ContextName[16];                    // Storage for a context name (to facilitate debugging multi-context setups)
     ImGuiIO                 IO;
     ImGuiPlatformIO         PlatformIO;
     ImGuiStyle              Style;
+    ImGuiConfigFlags        ConfigFlagsCurrFrame;               // = g.IO.ConfigFlags at the time of NewFrame()
+    ImGuiConfigFlags        ConfigFlagsLastFrame;
     ImVector<ImFontAtlas*>  FontAtlases;                        // List of font atlases used by the context (generally only contains g.IO.Fonts aka the main font atlas)
     ImFont*                 Font;                               // Currently bound font. (== FontStack.back().Font)
     ImFontBaked*            FontBaked;                          // Currently bound font at currently bound size. (== Font->GetFontBaked(FontSize))
@@ -2231,7 +2428,7 @@
     ImGuiWindow*            HoveredWindow;                      // Window the mouse is hovering. Will typically catch mouse inputs.
     ImGuiWindow*            HoveredWindowUnderMovingWindow;     // Hovered window ignoring MovingWindow. Only set if MovingWindow is set.
     ImGuiWindow*            HoveredWindowBeforeClear;           // Window the mouse is hovering. Filled even with _NoMouse. This is currently useful for multi-context compositors.
-    ImGuiWindow*            MovingWindow;                       // Track the window we clicked on (in order to preserve focus). The actual window that is moved is generally MovingWindow->RootWindow.
+    ImGuiWindow*            MovingWindow;                       // Track the window we clicked on (in order to preserve focus). The actual window that is moved is generally MovingWindow->RootWindowDockTree.
     ImGuiWindow*            WheelingWindow;                     // Track the window we started mouse-wheeling on. Until a timer elapse or mouse has moved, generally keep scrolling the same window even if during the course of scrolling the mouse ends up hovering a child window.
     ImVec2                  WheelingWindowRefMousePos;
     int                     WheelingWindowStartFrame;           // This may be set one frame before WheelingWindow is != NULL
@@ -2310,7 +2507,16 @@
     ImVector<ImGuiTreeNodeStackData>TreeNodeStack;              // Stack for TreeNode()
 
     // Viewports
-    ImVector<ImGuiViewportP*> Viewports;                        // Active viewports (Size==1 in 'master' branch). Each viewports hold their copy of ImDrawData.
+    ImVector<ImGuiViewportP*> Viewports;                        // Active viewports (always 1+, and generally 1 unless multi-viewports are enabled). Each viewports hold their copy of ImDrawData.
+    ImGuiViewportP*         CurrentViewport;                    // We track changes of viewport (happening in Begin) so we can call Platform_OnChangedViewport()
+    ImGuiViewportP*         MouseViewport;
+    ImGuiViewportP*         MouseLastHoveredViewport;           // Last known viewport that was hovered by mouse (even if we are not hovering any viewport any more) + honoring the _NoInputs flag.
+    ImGuiID                 PlatformLastFocusedViewportId;
+    ImGuiPlatformMonitor    FallbackMonitor;                    // Virtual monitor used as fallback if backend doesn't provide monitor information.
+    ImRect                  PlatformMonitorsFullWorkRect;       // Bounding box of all platform monitors
+    int                     ViewportCreatedCount;               // Unique sequential creation counter (mostly for testing/debugging)
+    int                     PlatformWindowsCreatedCount;        // Unique sequential creation counter (mostly for testing/debugging)
+    int                     ViewportFocusedStampCount;          // Every time the front-most window changes, we stamp its viewport with an incrementing counter
 
     // Keyboard/Gamepad Navigation
     bool                    NavCursorVisible;                   // Nav focus cursor/rectangle is visible? We hide it after a mouse click. We show it after a nav move.
@@ -2496,6 +2702,8 @@
     // Extensions
     // FIXME: We could provide an API to register one slot in an array held in ImGuiContext?
     ImVector<ImTextureData*> UserTextures;                      // List of textures created/managed by user or third-party extension. Automatically appended into platform_io.Textures[].
+    ImGuiDockContext        DockContext;
+    void                    (*DockNodeWindowMenuHandler)(ImGuiContext* ctx, ImGuiDockNode* node, ImGuiTabBar* tab_bar);
 
     // Settings
     bool                    SettingsLoaded;
@@ -2555,6 +2763,7 @@
     ImGuiDebugItemPathQuery DebugItemPathQuery;
     ImGuiIDStackTool        DebugIDStackTool;
     ImGuiDebugAllocInfo     DebugAllocInfo;
+    ImGuiDockNode*          DebugHoveredDockNode;               // Hovered dock node.
 #if defined(IMGUI_DEBUG_HIGHLIGHT_ALL_ID_CONFLICTS) && !defined(IMGUI_DISABLE_DEBUG_TOOLS)
     ImGuiStorage            DebugDrawIdConflictsAliveCount;
     ImGuiStorage            DebugDrawIdConflictsHighlightSet;
@@ -2625,8 +2834,12 @@
     ImGuiLayoutType         LayoutType;
     ImGuiLayoutType         ParentLayoutType;       // Layout type of parent window at the time of Begin()
     ImU32                   ModalDimBgColor;
+
+    // Status flags
     ImGuiItemStatusFlags    WindowItemStatusFlags;
     ImGuiItemStatusFlags    ChildItemStatusFlags;
+    ImGuiItemStatusFlags    DockTabItemStatusFlags;
+    ImRect                  DockTabItemRect;
 
     // Local parameters stacks
     // We store the current settings outside of the vectors to increase memory locality (reduce cache misses). The vectors are rarely modified. Also it allows us to not heap allocate for short-lived windows which are not using those settings.
@@ -2643,9 +2856,13 @@
     ImGuiContext*           Ctx;                                // Parent UI context (needs to be set explicitly by parent).
     char*                   Name;                               // Window name, owned by the window.
     ImGuiID                 ID;                                 // == ImHashStr(Name)
-    ImGuiWindowFlags        Flags;                              // See enum ImGuiWindowFlags_
+    ImGuiWindowFlags        Flags, FlagsPreviousFrame;          // See enum ImGuiWindowFlags_
     ImGuiChildFlags         ChildFlags;                         // Set when window is a child window. See enum ImGuiChildFlags_
+    ImGuiWindowClass        WindowClass;                        // Advanced users only. Set with SetNextWindowClass()
     ImGuiViewportP*         Viewport;                           // Always set in Begin(). Inactive windows may have a NULL value here if their viewport was discarded.
+    ImGuiID                 ViewportId;                         // We backup the viewport id (since the viewport may disappear or never be created if the window is inactive)
+    ImVec2                  ViewportPos;                        // We backup the viewport position (since the viewport may disappear or never be created if the window is inactive)
+    int                     ViewportAllowPlatformMonitorExtend; // Reset to -1 every frame (index is guaranteed to be valid between NewFrame..EndFrame), only used in the Appearing frame of a tooltip/popup to enforce clamping to a given monitor
     ImVec2                  Pos;                                // Position (always rounded-up to nearest pixel)
     ImVec2                  Size;                               // Current size (==SizeFull or collapsed title bar size)
     ImVec2                  SizeFull;                           // Size when non collapsed
@@ -2661,6 +2878,7 @@
     float                   DecoInnerSizeX1, DecoInnerSizeY1;   // Applied AFTER/OVER InnerRect. Specialized for Tables as they use specialized form of clipping and frozen rows/columns are inside InnerRect (and not part of regular decoration sizes).
     int                     NameBufLen;                         // Size of buffer storing Name. May be larger than strlen(Name)!
     ImGuiID                 MoveId;                             // == window->GetID("#MOVE")
+    ImGuiID                 TabId;                              // == window->GetID("#TAB")
     ImGuiID                 ChildId;                            // ID of corresponding item in parent window (for navigation to return from child window to parent window)
     ImGuiID                 PopupId;                            // ID in the popup stack when this window is used as a popup/menu (because we use generic Name/ID for recycling)
     ImVec2                  Scroll;
@@ -2672,6 +2890,7 @@
     bool                    ScrollbarX, ScrollbarY;             // Are scrollbars visible?
     bool                    ScrollbarXStabilizeEnabled;         // Was ScrollbarX previously auto-stabilized?
     ImU8                    ScrollbarXStabilizeToggledHistory;  // Used to stabilize scrollbar visibility in case of feedback loops
+    bool                    ViewportOwned;
     bool                    Active;                             // Set to true on Begin(), unless Collapsed
     bool                    WasActive;
     bool                    WriteAccessed;                      // Set to true when any widget access the current window
@@ -2702,6 +2921,7 @@
     ImGuiCond               SetWindowPosAllowFlags : 8;         // store acceptable condition flags for SetNextWindowPos() use.
     ImGuiCond               SetWindowSizeAllowFlags : 8;        // store acceptable condition flags for SetNextWindowSize() use.
     ImGuiCond               SetWindowCollapsedAllowFlags : 8;   // store acceptable condition flags for SetNextWindowCollapsed() use.
+    ImGuiCond               SetWindowDockAllowFlags : 8;        // store acceptable condition flags for SetNextWindowDock() use.
     ImVec2                  SetWindowPosVal;                    // store window position when using a non-zero Pivot (position set needs to be processed when we know the window size)
     ImVec2                  SetWindowPosPivot;                  // store window pivot for positioning. ImVec2(0, 0) when positioning from top-left corner; ImVec2(0.5f, 0.5f) for centering; ImVec2(1, 1) for bottom right.
 
@@ -2721,6 +2941,7 @@
     ImVec2ih                HitTestHoleOffset;
 
     int                     LastFrameActive;                    // Last frame number the window was Active.
+    int                     LastFrameJustFocused;               // Last frame number the window was made Focused.
     float                   LastTimeActive;                     // Last timestamp the window was Active (using float as we don't need high precision there)
     ImGuiStorage            StateStorage;
     ImVector<ImGuiOldColumns> ColumnsStorage;
@@ -2735,6 +2956,7 @@
     ImGuiWindow*            ParentWindowInBeginStack;
     ImGuiWindow*            RootWindow;                         // Point to ourself or first ancestor that is not a child window. Doesn't cross through popups/dock nodes.
     ImGuiWindow*            RootWindowPopupTree;                // Point to ourself or first ancestor that is not a child window. Cross through popups parent<>child.
+    ImGuiWindow*            RootWindowDockTree;                 // Point to ourself or first ancestor that is not a child window. Cross through dock nodes.
     ImGuiWindow*            RootWindowForTitleBarHighlight;     // Point to ourself or first ancestor which will display TitleBgActive color when this window is active.
     ImGuiWindow*            RootWindowForNav;                   // Point to ourself or first ancestor which doesn't have the NavFlattened flag.
     ImGuiWindow*            ParentWindowForFocusRoute;          // Set to manual link a window to its logical parent so that Shortcut() chain are honored (e.g. Tool linked to Document)
@@ -2749,6 +2971,17 @@
     int                     MemoryDrawListVtxCapacity;
     bool                    MemoryCompacted;                    // Set when window extraneous data have been garbage collected
 
+    // Docking
+    bool                    DockIsActive        :1;             // When docking artifacts are actually visible. When this is set, DockNode is guaranteed to be != NULL. ~~ (DockNode != NULL) && (DockNode->Windows.Size > 1).
+    bool                    DockNodeIsVisible   :1;
+    bool                    DockTabIsVisible    :1;             // Is our window visible this frame? ~~ is the corresponding tab selected?
+    bool                    DockTabWantClose    :1;
+    short                   DockOrder;                          // Order of the last time the window was visible within its DockNode. This is used to reorder windows that are reappearing on the same frame. Same value between windows that were active and windows that were none are possible.
+    ImGuiWindowDockStyle    DockStyle;
+    ImGuiDockNode*          DockNode;                           // Which node are we docked into. Important: Prefer testing DockIsActive in many cases as this will still be set when the dock node is hidden.
+    ImGuiDockNode*          DockNodeAsHost;                     // Which node are we owning (for parent windows)
+    ImGuiID                 DockId;                             // Backup of last valid DockNode->ID, so single window remember their dock node id even when they are not bound any more
+
 public:
     ImGuiWindow(ImGuiContext* context, const char* name);
     ~ImGuiWindow();
@@ -2765,7 +2998,7 @@
     ImRect      MenuBarRect() const     { float y1 = Pos.y + TitleBarHeight; return ImRect(Pos.x, y1, Pos.x + SizeFull.x, y1 + MenuBarHeight); }
 
     // [OBSOLETE] ImGuiWindow::CalcFontSize() was removed in 1.92.0 because error-prone/misleading. You can use window->FontRefSize for a copy of g.FontSize at the time of the last Begin() call for this window.
-    //float     CalcFontSize() const    { ImGuiContext& g = *Ctx; return g.FontSizeBase * FontWindowScale * FontWindowScaleParents;
+    //float     CalcFontSize() const    { ImGuiContext& g = *Ctx; return g.FontSizeBase * FontWindowScale * FontDpiScale * FontWindowScaleParents;
 };
 
 //-----------------------------------------------------------------------------
@@ -2787,14 +3020,15 @@
     ImGuiTabItemFlags_NoCloseButton             = 1 << 20,  // Track whether p_open was set or not (we'll need this info on the next frame to recompute ContentWidth during layout)
     ImGuiTabItemFlags_Button                    = 1 << 21,  // Used by TabItemButton, change the tab item behavior to mimic a button
     ImGuiTabItemFlags_Invisible                 = 1 << 22,  // To reserve space e.g. with ImGuiTabItemFlags_Leading
-    //ImGuiTabItemFlags_Unsorted                = 1 << 23,  // [Docking] Trailing tabs with the _Unsorted flag will be sorted based on the DockOrder of their Window.
+    ImGuiTabItemFlags_Unsorted                  = 1 << 23,  // [Docking] Trailing tabs with the _Unsorted flag will be sorted based on the DockOrder of their Window.
 };
 
-// Storage for one active tab item (sizeof() 40 bytes)
+// Storage for one active tab item (sizeof() 48 bytes)
 struct ImGuiTabItem
 {
     ImGuiID             ID;
     ImGuiTabItemFlags   Flags;
+    ImGuiWindow*        Window;                 // When TabItem is part of a DockNode's TabBar, we hold on to a window.
     int                 LastFrameVisible;
     int                 LastFrameSelected;      // This allows us to infer an ordered list of the last activated tabs with little maintenance
     float               Offset;                 // Position relative to beginning of tab bar
@@ -3164,7 +3398,7 @@
     IMGUI_API void          UpdateWindowParentAndRootLinks(ImGuiWindow* window, ImGuiWindowFlags flags, ImGuiWindow* parent_window);
     IMGUI_API void          UpdateWindowSkipRefresh(ImGuiWindow* window);
     IMGUI_API ImVec2        CalcWindowNextAutoFitSize(ImGuiWindow* window);
-    IMGUI_API bool          IsWindowChildOf(ImGuiWindow* window, ImGuiWindow* potential_parent, bool popup_hierarchy);
+    IMGUI_API bool          IsWindowChildOf(ImGuiWindow* window, ImGuiWindow* potential_parent, bool popup_hierarchy, bool dock_hierarchy);
     IMGUI_API bool          IsWindowInBeginStack(ImGuiWindow* window);
     IMGUI_API bool          IsWindowWithinBeginStackOf(ImGuiWindow* window, ImGuiWindow* potential_parent);
     IMGUI_API bool          IsWindowAbove(ImGuiWindow* potential_above, ImGuiWindow* potential_below);
@@ -3174,7 +3408,7 @@
     IMGUI_API void          SetWindowCollapsed(ImGuiWindow* window, bool collapsed, ImGuiCond cond = 0);
     IMGUI_API void          SetWindowHitTestHole(ImGuiWindow* window, const ImVec2& pos, const ImVec2& size);
     IMGUI_API void          SetWindowHiddenAndSkipItemsForCurrentFrame(ImGuiWindow* window);
-    inline void             SetWindowParentWindowForFocusRoute(ImGuiWindow* window, ImGuiWindow* parent_window) { window->ParentWindowForFocusRoute = parent_window; }
+    inline void             SetWindowParentWindowForFocusRoute(ImGuiWindow* window, ImGuiWindow* parent_window) { window->ParentWindowForFocusRoute = parent_window; } // You may also use SetNextWindowClass()'s FocusRouteParentWindowId field.
     inline ImRect           WindowRectAbsToRel(ImGuiWindow* window, const ImRect& r) { ImVec2 off = window->DC.CursorStartPos; return ImRect(r.Min.x - off.x, r.Min.y - off.y, r.Max.x - off.x, r.Max.y - off.y); }
     inline ImRect           WindowRectRelToAbs(ImGuiWindow* window, const ImRect& r) { ImVec2 off = window->DC.CursorStartPos; return ImRect(r.Min.x + off.x, r.Min.y + off.y, r.Max.x + off.x, r.Max.y + off.y); }
     inline ImVec2           WindowPosAbsToRel(ImGuiWindow* window, const ImVec2& p)  { ImVec2 off = window->DC.CursorStartPos; return ImVec2(p.x - off.x, p.y - off.y); }
@@ -3206,9 +3440,7 @@
     IMGUI_API ImFont*       GetDefaultFont();
     IMGUI_API void          PushPasswordFont();
     IMGUI_API void          PopPasswordFont();
-    inline ImDrawList*      GetForegroundDrawList(ImGuiWindow* window) { IM_UNUSED(window); return GetForegroundDrawList(); } // This seemingly unnecessary wrapper simplifies compatibility between the 'master' and 'docking' branches.
-    IMGUI_API ImDrawList*   GetBackgroundDrawList(ImGuiViewport* viewport);                     // get background draw list for the given viewport. this draw list will be the first rendering one. Useful to quickly draw shapes/text behind dear imgui contents.
-    IMGUI_API ImDrawList*   GetForegroundDrawList(ImGuiViewport* viewport);                     // get foreground draw list for the given viewport. this draw list will be the last rendered one. Useful to quickly draw shapes/text over dear imgui contents.
+    inline ImDrawList*      GetForegroundDrawList(ImGuiWindow* window) { return GetForegroundDrawList(window->Viewport); }
     IMGUI_API void          AddDrawListToDrawDataEx(ImDrawData* draw_data, ImVector<ImDrawList*>* out_list, ImDrawList* draw_list);
 
     // Init
@@ -3226,14 +3458,19 @@
     IMGUI_API void          UpdateHoveredWindowAndCaptureFlags(const ImVec2& mouse_pos);
     IMGUI_API void          FindHoveredWindowEx(const ImVec2& pos, bool find_first_and_in_any_viewport, ImGuiWindow** out_hovered_window, ImGuiWindow** out_hovered_window_under_moving_window);
     IMGUI_API void          StartMouseMovingWindow(ImGuiWindow* window);
+    IMGUI_API void          StartMouseMovingWindowOrNode(ImGuiWindow* window, ImGuiDockNode* node, bool undock);
     IMGUI_API void          StopMouseMovingWindow();
     IMGUI_API void          UpdateMouseMovingWindowNewFrame();
     IMGUI_API void          UpdateMouseMovingWindowEndFrame();
 
     // Viewports
-    inline ImGuiViewport*   GetWindowViewport() { return GetMainViewport(); } // For code consistency. This is public API in docking branch.
+    IMGUI_API void          TranslateWindowsInViewport(ImGuiViewportP* viewport, const ImVec2& old_pos, const ImVec2& new_pos, const ImVec2& old_size, const ImVec2& new_size);
     IMGUI_API void          ScaleWindowsInViewport(ImGuiViewportP* viewport, float scale);
+    IMGUI_API void          DestroyPlatformWindow(ImGuiViewportP* viewport);
     IMGUI_API void          SetWindowViewport(ImGuiWindow* window, ImGuiViewportP* viewport);
+    IMGUI_API void          SetCurrentViewport(ImGuiWindow* window, ImGuiViewportP* viewport);
+    IMGUI_API const ImGuiPlatformMonitor*   GetViewportPlatformMonitor(ImGuiViewport* viewport);
+    IMGUI_API ImGuiViewportP*               FindHoveredViewportFromPlatformWindowStack(const ImVec2& mouse_platform_pos);
 
     // Settings
     IMGUI_API void                  MarkIniSettingsDirty();
@@ -3450,6 +3687,61 @@
     IMGUI_API bool          TestShortcutRouting(ImGuiKeyChord key_chord, ImGuiID owner_id);
     IMGUI_API ImGuiKeyRoutingData* GetShortcutRoutingData(ImGuiKeyChord key_chord);
 
+    // Docking
+    // (some functions are only declared in imgui.cpp, see Docking section)
+    IMGUI_API void          DockContextInitialize(ImGuiContext* ctx);
+    IMGUI_API void          DockContextShutdown(ImGuiContext* ctx);
+    IMGUI_API void          DockContextClearNodes(ImGuiContext* ctx, ImGuiID root_id, bool clear_settings_refs); // Use root_id==0 to clear all
+    IMGUI_API void          DockContextRebuildNodes(ImGuiContext* ctx);
+    IMGUI_API void          DockContextNewFrameUpdateUndocking(ImGuiContext* ctx);
+    IMGUI_API void          DockContextNewFrameUpdateDocking(ImGuiContext* ctx);
+    IMGUI_API void          DockContextEndFrame(ImGuiContext* ctx);
+    IMGUI_API ImGuiID       DockContextGenNodeID(ImGuiContext* ctx);
+    IMGUI_API void          DockContextQueueDock(ImGuiContext* ctx, ImGuiWindow* target, ImGuiDockNode* target_node, ImGuiWindow* payload, ImGuiDir split_dir, float split_ratio, bool split_outer);
+    IMGUI_API void          DockContextQueueUndockWindow(ImGuiContext* ctx, ImGuiWindow* window);
+    IMGUI_API void          DockContextQueueUndockNode(ImGuiContext* ctx, ImGuiDockNode* node);
+    IMGUI_API void          DockContextProcessUndockWindow(ImGuiContext* ctx, ImGuiWindow* window, bool clear_persistent_docking_ref = true);
+    IMGUI_API void          DockContextProcessUndockNode(ImGuiContext* ctx, ImGuiDockNode* node);
+    IMGUI_API bool          DockContextCalcDropPosForDocking(ImGuiWindow* target, ImGuiDockNode* target_node, ImGuiWindow* payload_window, ImGuiDockNode* payload_node, ImGuiDir split_dir, bool split_outer, ImVec2* out_pos);
+    IMGUI_API ImGuiDockNode*DockContextFindNodeByID(ImGuiContext* ctx, ImGuiID id);
+    IMGUI_API void          DockNodeWindowMenuHandler_Default(ImGuiContext* ctx, ImGuiDockNode* node, ImGuiTabBar* tab_bar);
+    IMGUI_API bool          DockNodeBeginAmendTabBar(ImGuiDockNode* node);
+    IMGUI_API void          DockNodeEndAmendTabBar();
+    inline ImGuiDockNode*   DockNodeGetRootNode(ImGuiDockNode* node)                 { while (node->ParentNode) node = node->ParentNode; return node; }
+    inline bool             DockNodeIsInHierarchyOf(ImGuiDockNode* node, ImGuiDockNode* parent) { while (node) { if (node == parent) return true; node = node->ParentNode; } return false; }
+    inline int              DockNodeGetDepth(const ImGuiDockNode* node)              { int depth = 0; while (node->ParentNode) { node = node->ParentNode; depth++; } return depth; }
+    inline ImGuiID          DockNodeGetWindowMenuButtonId(const ImGuiDockNode* node) { return ImHashStr("#COLLAPSE", 0, node->ID); }
+    inline ImGuiDockNode*   GetWindowDockNode()                                      { ImGuiContext& g = *GImGui; return g.CurrentWindow->DockNode; }
+    IMGUI_API bool          GetWindowAlwaysWantOwnTabBar(ImGuiWindow* window);
+    IMGUI_API void          BeginDocked(ImGuiWindow* window, bool* p_open);
+    IMGUI_API void          BeginDockableDragDropSource(ImGuiWindow* window);
+    IMGUI_API void          BeginDockableDragDropTarget(ImGuiWindow* window);
+    IMGUI_API void          SetWindowDock(ImGuiWindow* window, ImGuiID dock_id, ImGuiCond cond);
+
+    // Docking - Builder function needs to be generally called before the node is used/submitted.
+    // - The DockBuilderXXX functions are designed to _eventually_ become a public API, but it is too early to expose it and guarantee stability.
+    // - Do not hold on ImGuiDockNode* pointers! They may be invalidated by any split/merge/remove operation and every frame.
+    // - To create a DockSpace() node, make sure to set the ImGuiDockNodeFlags_DockSpace flag when calling DockBuilderAddNode().
+    //   You can create dockspace nodes (attached to a window) _or_ floating nodes (carry its own window) with this API.
+    // - DockBuilderSplitNode() create 2 child nodes within 1 node. The initial node becomes a parent node.
+    // - If you intend to split the node immediately after creation using DockBuilderSplitNode(), make sure
+    //   to call DockBuilderSetNodeSize() beforehand. If you don't, the resulting split sizes may not be reliable.
+    // - Call DockBuilderFinish() after you are done.
+    IMGUI_API void          DockBuilderDockWindow(const char* window_name, ImGuiID node_id);
+    IMGUI_API ImGuiDockNode*DockBuilderGetNode(ImGuiID node_id);
+    inline ImGuiDockNode*   DockBuilderGetCentralNode(ImGuiID node_id)              { ImGuiDockNode* node = DockBuilderGetNode(node_id); if (!node) return NULL; return DockNodeGetRootNode(node)->CentralNode; }
+    IMGUI_API ImGuiID       DockBuilderAddNode(ImGuiID node_id = 0, ImGuiDockNodeFlags flags = 0);
+    IMGUI_API void          DockBuilderRemoveNode(ImGuiID node_id);                 // Remove node and all its child, undock all windows
+    IMGUI_API void          DockBuilderRemoveNodeDockedWindows(ImGuiID node_id, bool clear_settings_refs = true);
+    IMGUI_API void          DockBuilderRemoveNodeChildNodes(ImGuiID node_id);       // Remove all split/hierarchy. All remaining docked windows will be re-docked to the remaining root node (node_id).
+    IMGUI_API void          DockBuilderSetNodePos(ImGuiID node_id, ImVec2 pos);
+    IMGUI_API void          DockBuilderSetNodeSize(ImGuiID node_id, ImVec2 size);
+    IMGUI_API ImGuiID       DockBuilderSplitNode(ImGuiID node_id, ImGuiDir split_dir, float size_ratio_for_node_at_dir, ImGuiID* out_id_at_dir, ImGuiID* out_id_at_opposite_dir); // Create 2 child nodes in this parent node.
+    IMGUI_API void          DockBuilderCopyDockSpace(ImGuiID src_dockspace_id, ImGuiID dst_dockspace_id, ImVector<const char*>* in_window_remap_pairs);
+    IMGUI_API void          DockBuilderCopyNode(ImGuiID src_node_id, ImGuiID dst_node_id, ImVector<ImGuiID>* out_node_remap_pairs);
+    IMGUI_API void          DockBuilderCopyWindowSettings(const char* src_name, const char* dst_name);
+    IMGUI_API void          DockBuilderFinish(ImGuiID node_id);
+
     // [EXPERIMENTAL] Focus Scope
     // This is generally used to identify a unique input location (for e.g. a selection set)
     // There is one per window (automatically set in Begin), but:
@@ -3570,9 +3862,11 @@
     IMGUI_API bool          BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& bb, ImGuiTabBarFlags flags);
     IMGUI_API ImGuiTabItem* TabBarFindTabByID(ImGuiTabBar* tab_bar, ImGuiID tab_id);
     IMGUI_API ImGuiTabItem* TabBarFindTabByOrder(ImGuiTabBar* tab_bar, int order);
+    IMGUI_API ImGuiTabItem* TabBarFindMostRecentlySelectedTabForActiveWindow(ImGuiTabBar* tab_bar);
     IMGUI_API ImGuiTabItem* TabBarGetCurrentTab(ImGuiTabBar* tab_bar);
     inline int              TabBarGetTabOrder(ImGuiTabBar* tab_bar, ImGuiTabItem* tab) { return tab_bar->Tabs.index_from_ptr(tab); }
     IMGUI_API const char*   TabBarGetTabName(ImGuiTabBar* tab_bar, ImGuiTabItem* tab);
+    IMGUI_API void          TabBarAddTab(ImGuiTabBar* tab_bar, ImGuiTabItemFlags tab_flags, ImGuiWindow* window);
     IMGUI_API void          TabBarRemoveTab(ImGuiTabBar* tab_bar, ImGuiID tab_id);
     IMGUI_API void          TabBarCloseTab(ImGuiTabBar* tab_bar, ImGuiTabItem* tab);
     IMGUI_API void          TabBarQueueFocus(ImGuiTabBar* tab_bar, ImGuiTabItem* tab);
@@ -3611,6 +3905,7 @@
     IMGUI_API void          RenderBullet(ImDrawList* draw_list, ImVec2 pos, ImU32 col);
     IMGUI_API void          RenderCheckMark(ImDrawList* draw_list, ImVec2 pos, ImU32 col, float sz);
     IMGUI_API void          RenderArrowPointingAt(ImDrawList* draw_list, ImVec2 pos, ImVec2 half_sz, ImGuiDir direction, ImU32 col);
+    IMGUI_API void          RenderArrowDockMenu(ImDrawList* draw_list, ImVec2 p_min, float sz, ImU32 col);
     IMGUI_API void          RenderRectFilledInRangeH(ImDrawList* draw_list, const ImRect& rect, ImU32 col, float fill_x0, float fill_x1, float rounding);
     IMGUI_API void          RenderRectFilledWithHole(ImDrawList* draw_list, const ImRect& outer, const ImRect& inner, ImU32 col, float rounding);
     IMGUI_API ImDrawFlags   CalcRoundingFlagsForRectInRect(const ImRect& r_in, const ImRect& r_outer, float threshold);
@@ -3631,7 +3926,7 @@
 
     // Widgets: Window Decorations
     IMGUI_API bool          CloseButton(ImGuiID id, const ImVec2& pos);
-    IMGUI_API bool          CollapseButton(ImGuiID id, const ImVec2& pos);
+    IMGUI_API bool          CollapseButton(ImGuiID id, const ImVec2& pos, ImGuiDockNode* dock_node);
     IMGUI_API void          Scrollbar(ImGuiAxis axis);
     IMGUI_API bool          ScrollbarEx(const ImRect& bb, ImGuiID id, ImGuiAxis axis, ImS64* p_scroll_v, ImS64 avail_v, ImS64 contents_v, ImDrawFlags draw_rounding_flags = 0);
     IMGUI_API ImRect        GetWindowScrollbarRect(ImGuiWindow* window, ImGuiAxis axis);
@@ -3728,6 +4023,7 @@
     IMGUI_API ImU64         DebugTextureIDToU64(ImTextureID tex_id);
     IMGUI_API void          DebugHookIdInfo(ImGuiID id, ImGuiDataType data_type, const void* data_id, const void* data_id_end);
     IMGUI_API void          DebugNodeColumns(ImGuiOldColumns* columns);
+    IMGUI_API void          DebugNodeDockNode(ImGuiDockNode* node, const char* label);
     IMGUI_API void          DebugNodeDrawList(ImGuiWindow* window, ImGuiViewportP* viewport, const ImDrawList* draw_list, const char* label);
     IMGUI_API void          DebugNodeDrawCmdShowMeshAndBoundingBox(ImDrawList* out_draw_list, const ImDrawList* draw_list, const ImDrawCmd* draw_cmd, bool show_mesh, bool show_aabb);
     IMGUI_API void          DebugNodeFont(ImFont* font);
@@ -3746,6 +4042,7 @@
     IMGUI_API void          DebugNodeWindowsList(ImVector<ImGuiWindow*>* windows, const char* label);
     IMGUI_API void          DebugNodeWindowsListByBeginStackParent(ImGuiWindow** windows, int windows_size, ImGuiWindow* parent_in_begin_stack);
     IMGUI_API void          DebugNodeViewport(ImGuiViewportP* viewport);
+    IMGUI_API void          DebugNodePlatformMonitor(ImGuiPlatformMonitor* monitor, const char* label, int idx);
     IMGUI_API void          DebugRenderKeyboardPreview(ImDrawList* draw_list);
     IMGUI_API void          DebugRenderViewportThumbnail(ImDrawList* draw_list, ImGuiViewportP* viewport, const ImRect& bb);
 

diff --git a/imgui_widgets.cpp b/imgui_widgets.cpp
index 23a75aa..75c4dc9 100644
--- a/imgui_widgets.cpp
+++ b/imgui_widgets.cpp

@@ -560,7 +560,7 @@
         flags |= (item_flags & ImGuiItemFlags_ButtonRepeat) ? ImGuiButtonFlags_PressedOnClick : ImGuiButtonFlags_PressedOnDefault_;
 
     ImGuiWindow* backup_hovered_window = g.HoveredWindow;
-    const bool flatten_hovered_children = (flags & ImGuiButtonFlags_FlattenChildren) && g.HoveredWindow && g.HoveredWindow->RootWindow == window->RootWindow;
+    const bool flatten_hovered_children = (flags & ImGuiButtonFlags_FlattenChildren) && g.HoveredWindow && g.HoveredWindow->RootWindowDockTree == window->RootWindowDockTree;
     if (flatten_hovered_children)
         g.HoveredWindow = window;
 
@@ -926,7 +926,8 @@
     return pressed;
 }
 
-bool ImGui::CollapseButton(ImGuiID id, const ImVec2& pos)
+// The Collapse button also functions as a Dock Menu button.
+bool ImGui::CollapseButton(ImGuiID id, const ImVec2& pos, ImGuiDockNode* dock_node)
 {
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
@@ -939,16 +940,21 @@
         return pressed;
 
     // Render
+    //bool is_dock_menu = (window->DockNodeAsHost && !window->Collapsed);
     ImU32 bg_col = GetColorU32((held && hovered) ? ImGuiCol_ButtonActive : hovered ? ImGuiCol_ButtonHovered : ImGuiCol_Button);
     ImU32 text_col = GetColorU32(ImGuiCol_Text);
     if (hovered || held)
         window->DrawList->AddRectFilled(bb.Min, bb.Max, bg_col);
     RenderNavCursor(bb, id, ImGuiNavRenderCursorFlags_Compact);
-    RenderArrow(window->DrawList, bb.Min, text_col, window->Collapsed ? ImGuiDir_Right : ImGuiDir_Down, 1.0f);
+
+    if (dock_node)
+        RenderArrowDockMenu(window->DrawList, bb.Min, g.FontSize, text_col);
+    else
+        RenderArrow(window->DrawList, bb.Min, text_col, window->Collapsed ? ImGuiDir_Right : ImGuiDir_Down, 1.0f);
 
     // Switch to moving the window after mouse is moved beyond the initial drag threshold
     if (IsItemActive() && IsMouseDragging(0))
-        StartMouseMovingWindow(window);
+        StartMouseMovingWindowOrNode(window, dock_node, true); // Undock from window/collapse menu button
 
     return pressed;
 }
@@ -982,7 +988,8 @@
 
     // Calculate scrollbar bounding box
     ImRect bb = GetWindowScrollbarRect(window, axis);
-    ImDrawFlags rounding_corners = CalcRoundingFlagsForRectInRect(bb, window->Rect(), g.Style.WindowBorderSize);
+    ImRect host_rect = (window->DockIsActive ? window->DockNode->HostWindow : window)->Rect();
+    ImDrawFlags rounding_corners = CalcRoundingFlagsForRectInRect(bb, host_rect, g.Style.WindowBorderSize);
     float size_visible = window->InnerRect.Max[axis] - window->InnerRect.Min[axis];
     float size_contents = window->ContentSize[axis] + window->WindowPadding[axis] * 2.0f;
     ImS64 scroll = (ImS64)window->Scroll[axis];
@@ -9006,9 +9013,10 @@
 
     // We don't clip with current window clipping rectangle as it is already set to the area below. However we clip with window full rect.
     // We remove 1 worth of rounding to Max.x to that text in long menus and small windows don't tend to display over the lower-right rounded area, which looks particularly glitchy.
-    const float border_top = ImMax(window->WindowBorderSize * 0.5f - window->TitleBarHeight, 0.0f);
+    const float border_top = ImMax(IM_ROUND(window->WindowBorderSize * 0.5f - window->TitleBarHeight), 0.0f);
+    const float border_half = IM_ROUND(window->WindowBorderSize * 0.5f);
     ImRect bar_rect = window->MenuBarRect();
-    ImRect clip_rect(IM_ROUND(bar_rect.Min.x + window->WindowBorderSize * 0.5f), IM_ROUND(bar_rect.Min.y + border_top), IM_ROUND(ImMax(bar_rect.Min.x, bar_rect.Max.x - ImMax(window->WindowRounding, window->WindowBorderSize * 0.5f))), IM_ROUND(bar_rect.Max.y));
+    ImRect clip_rect(ImFloor(bar_rect.Min.x + border_half), ImFloor(bar_rect.Min.y + border_top), ImFloor(ImMax(bar_rect.Min.x, bar_rect.Max.x - ImMax(window->WindowRounding, border_half))), ImFloor(bar_rect.Max.y));
     clip_rect.ClipWith(window->OuterRectClipped);
     PushClipRect(clip_rect.Min, clip_rect.Max, false);
 
@@ -9089,10 +9097,10 @@
     IM_ASSERT(dir != ImGuiDir_None);
 
     ImGuiWindow* bar_window = FindWindowByName(name);
+    ImGuiViewportP* viewport = (ImGuiViewportP*)(void*)(viewport_p ? viewport_p : GetMainViewport());
     if (bar_window == NULL || bar_window->BeginCount == 0)
     {
         // Calculate and set window size/position
-        ImGuiViewportP* viewport = (ImGuiViewportP*)(void*)(viewport_p ? viewport_p : GetMainViewport());
         ImRect avail_rect = viewport->GetBuildWorkRect();
         ImGuiAxis axis = (dir == ImGuiDir_Up || dir == ImGuiDir_Down) ? ImGuiAxis_Y : ImGuiAxis_X;
         ImVec2 pos = avail_rect.Min;
@@ -9110,7 +9118,8 @@
             viewport->BuildWorkInsetMax[axis] += axis_size;
     }
 
-    window_flags |= ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoMove;
+    window_flags |= ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoDocking;
+    SetNextWindowViewport(viewport->ID); // Enforce viewport so we don't create our own viewport when ImGuiConfigFlags_ViewportsNoMerge is set.
     PushStyleVar(ImGuiStyleVar_WindowRounding, 0.0f);
     PushStyleVar(ImGuiStyleVar_WindowMinSize, ImVec2(0, 0)); // Lift normal size constraint
     bool is_open = Begin(name, NULL, window_flags);
@@ -9124,6 +9133,9 @@
     ImGuiContext& g = *GImGui;
     ImGuiViewportP* viewport = (ImGuiViewportP*)(void*)GetMainViewport();
 
+    // Notify of viewport change so GetFrameHeight() can be accurate in case of DPI change
+    SetCurrentViewport(NULL, viewport);
+
     // For the main menu bar, which cannot be moved, we honor g.Style.DisplaySafeAreaPadding to ensure text can be visible on a TV set.
     // FIXME: This could be generalized as an opt-in way to clamp window->DC.CursorStartPos to avoid SafeArea?
     // FIXME: Consider removing support for safe area down the line... it's messy. Nowadays consoles have support for TV calibration in OS settings.
@@ -9181,7 +9193,7 @@
     const ImGuiPopupData* upper_popup = &g.OpenPopupStack[g.BeginPopupStack.Size];
     if (window->DC.NavLayerCurrent != upper_popup->ParentNavLayer)
         return false;
-    return upper_popup->Window && (upper_popup->Window->Flags & ImGuiWindowFlags_ChildMenu) && ImGui::IsWindowChildOf(upper_popup->Window, window, true);
+    return upper_popup->Window && (upper_popup->Window->Flags & ImGuiWindowFlags_ChildMenu) && ImGui::IsWindowChildOf(upper_popup->Window, window, true, false);
 }
 
 bool ImGui::BeginMenuEx(const char* label, const char* icon, bool enabled)
@@ -9526,8 +9538,10 @@
 // - TabBarCalcMaxTabWidth() [Internal]
 // - TabBarFindTabById() [Internal]
 // - TabBarFindTabByOrder() [Internal]
+// - TabBarFindMostRecentlySelectedTabForActiveWindow() [Internal]
 // - TabBarGetCurrentTab() [Internal]
 // - TabBarGetTabName() [Internal]
+// - TabBarAddTab() [Internal]
 // - TabBarRemoveTab() [Internal]
 // - TabBarCloseTab() [Internal]
 // - TabBarScrollClamp() [Internal]
@@ -9644,7 +9658,7 @@
         return false;
 
     IM_ASSERT(tab_bar->ID != 0);
-    if ((flags & ImGuiTabBarFlags_DockNode) == 0)
+    if ((flags & ImGuiTabBarFlags_DockNode) == 0) // Already done
         PushOverrideID(tab_bar->ID);
 
     // Add to stack
@@ -9663,7 +9677,8 @@
 
     // Ensure correct ordering when toggling ImGuiTabBarFlags_Reorderable flag, or when a new tab was added while being not reorderable
     if ((flags & ImGuiTabBarFlags_Reorderable) != (tab_bar->Flags & ImGuiTabBarFlags_Reorderable) || (tab_bar->TabsAddedNew && !(flags & ImGuiTabBarFlags_Reorderable)))
-        ImQsort(tab_bar->Tabs.Data, tab_bar->Tabs.Size, sizeof(ImGuiTabItem), TabItemComparerByBeginOrder);
+        if ((flags & ImGuiTabBarFlags_DockNode) == 0) // FIXME: TabBar with DockNode can now be hybrid
+            ImQsort(tab_bar->Tabs.Data, tab_bar->Tabs.Size, sizeof(ImGuiTabItem), TabItemComparerByBeginOrder);
     tab_bar->TabsAddedNew = false;
 
     // Flags
@@ -9726,7 +9741,7 @@
         window->DC.CursorPos = tab_bar->BackupCursorPos;
 
     tab_bar->LastTabItemIdx = -1;
-    if ((tab_bar->Flags & ImGuiTabBarFlags_DockNode) == 0)
+    if ((tab_bar->Flags & ImGuiTabBarFlags_DockNode) == 0) // Already done
         PopID();
 
     g.CurrentTabBarStack.pop_back();
@@ -9968,6 +9983,10 @@
     tab_bar->VisibleTabId = tab_bar->SelectedTabId;
     tab_bar->VisibleTabWasSubmitted = false;
 
+    // CTRL+TAB can override visible tab temporarily
+    if (g.NavWindowingTarget != NULL && g.NavWindowingTarget->DockNode && g.NavWindowingTarget->DockNode->TabBar == tab_bar)
+        tab_bar->VisibleTabId = scroll_to_tab_id = g.NavWindowingTarget->TabId;
+
     // Apply request requests
     if (scroll_to_tab_id != 0)
         TabBarScrollToTab(tab_bar, scroll_to_tab_id, sections);
@@ -10013,11 +10032,11 @@
 // Dockable windows uses Name/ID in the global namespace. Non-dockable items use the ID stack.
 static ImU32   ImGui::TabBarCalcTabID(ImGuiTabBar* tab_bar, const char* label, ImGuiWindow* docked_window)
 {
-    IM_ASSERT(docked_window == NULL); // master branch only
-    IM_UNUSED(docked_window);
-    if (tab_bar->Flags & ImGuiTabBarFlags_DockNode)
+    if (docked_window != NULL)
     {
-        ImGuiID id = ImHashStr(label);
+        IM_UNUSED(tab_bar);
+        IM_ASSERT(tab_bar->Flags & ImGuiTabBarFlags_DockNode);
+        ImGuiID id = docked_window->TabId;
         KeepAliveID(id);
         return id;
     }
@@ -10051,6 +10070,20 @@
     return &tab_bar->Tabs[order];
 }
 
+// FIXME: See references to #2304 in TODO.txt
+ImGuiTabItem* ImGui::TabBarFindMostRecentlySelectedTabForActiveWindow(ImGuiTabBar* tab_bar)
+{
+    ImGuiTabItem* most_recently_selected_tab = NULL;
+    for (int tab_n = 0; tab_n < tab_bar->Tabs.Size; tab_n++)
+    {
+        ImGuiTabItem* tab = &tab_bar->Tabs[tab_n];
+        if (most_recently_selected_tab == NULL || most_recently_selected_tab->LastFrameSelected < tab->LastFrameSelected)
+            if (tab->Window && tab->Window->WasActive)
+                most_recently_selected_tab = tab;
+    }
+    return most_recently_selected_tab;
+}
+
 ImGuiTabItem* ImGui::TabBarGetCurrentTab(ImGuiTabBar* tab_bar)
 {
     if (tab_bar->LastTabItemIdx < 0 || tab_bar->LastTabItemIdx >= tab_bar->Tabs.Size)
@@ -10060,12 +10093,35 @@
 
 const char* ImGui::TabBarGetTabName(ImGuiTabBar* tab_bar, ImGuiTabItem* tab)
 {
+    if (tab->Window)
+        return tab->Window->Name;
     if (tab->NameOffset == -1)
         return "N/A";
     IM_ASSERT(tab->NameOffset < tab_bar->TabsNames.Buf.Size);
     return tab_bar->TabsNames.Buf.Data + tab->NameOffset;
 }
 
+// The purpose of this call is to register tab in advance so we can control their order at the time they appear.
+// Otherwise calling this is unnecessary as tabs are appending as needed by the BeginTabItem() function.
+void ImGui::TabBarAddTab(ImGuiTabBar* tab_bar, ImGuiTabItemFlags tab_flags, ImGuiWindow* window)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(TabBarFindTabByID(tab_bar, window->TabId) == NULL);
+    IM_ASSERT(g.CurrentTabBar != tab_bar);  // Can't work while the tab bar is active as our tab doesn't have an X offset yet, in theory we could/should test something like (tab_bar->CurrFrameVisible < g.FrameCount) but we'd need to solve why triggers the commented early-out assert in BeginTabBarEx() (probably dock node going from implicit to explicit in same frame)
+
+    if (!window->HasCloseButton)
+        tab_flags |= ImGuiTabItemFlags_NoCloseButton;       // Set _NoCloseButton immediately because it will be used for first-frame width calculation.
+
+    ImGuiTabItem new_tab;
+    new_tab.ID = window->TabId;
+    new_tab.Flags = tab_flags;
+    new_tab.LastFrameVisible = tab_bar->CurrFrameVisible;   // Required so BeginTabBar() doesn't ditch the tab
+    if (new_tab.LastFrameVisible == -1)
+        new_tab.LastFrameVisible = g.FrameCount - 1;
+    new_tab.Window = window;                                // Required so tab bar layout can compute the tab width before tab submission
+    tab_bar->Tabs.push_back(new_tab);
+}
+
 // The *TabId fields are already set by the docking system _before_ the actual TabItem was created, so we clear them regardless.
 void ImGui::TabBarRemoveTab(ImGuiTabBar* tab_bar, ImGuiID tab_id)
 {
@@ -10467,11 +10523,14 @@
     const bool is_tab_button = (flags & ImGuiTabItemFlags_Button) != 0;
     tab->LastFrameVisible = g.FrameCount;
     tab->Flags = flags;
+    tab->Window = docked_window;
 
     // Append name _WITH_ the zero-terminator
+    // (regular tabs are permitted in a DockNode tab bar, but window tabs not permitted in a non-DockNode tab bar)
     if (docked_window != NULL)
     {
-        IM_ASSERT(docked_window == NULL); // master branch only
+        IM_ASSERT(tab_bar->Flags & ImGuiTabBarFlags_DockNode);
+        tab->NameOffset = -1;
     }
     else
     {
@@ -10496,7 +10555,7 @@
         tab_bar->VisibleTabWasSubmitted = true;
 
     // On the very first frame of a tab bar we let first tab contents be visible to minimize appearing glitches
-    if (!tab_contents_visible && tab_bar->SelectedTabId == 0 && tab_bar_appearing)
+    if (!tab_contents_visible && tab_bar->SelectedTabId == 0 && tab_bar_appearing && docked_window == NULL)
         if (tab_bar->Tabs.Size == 1 && !(tab_bar->Flags & ImGuiTabBarFlags_AutoSelectNewTabs))
             tab_contents_visible = true;
 
@@ -10544,9 +10603,8 @@
     }
 
     // Click to Select a tab
-    // Allow the close button to overlap
     ImGuiButtonFlags button_flags = ((is_tab_button ? ImGuiButtonFlags_PressedOnClickRelease : ImGuiButtonFlags_PressedOnClick) | ImGuiButtonFlags_AllowOverlap);
-    if (g.DragDropActive)
+    if (g.DragDropActive && !g.DragDropPayload.IsDataType(IMGUI_PAYLOAD_TYPE_WINDOW)) // FIXME: May be an opt-in property of the payload to disable this
         button_flags |= ImGuiButtonFlags_PressedOnDragDropHold;
     bool hovered, held, pressed;
     if (flags & ImGuiTabItemFlags_Invisible)
@@ -10556,21 +10614,74 @@
     if (pressed && !is_tab_button)
         TabBarQueueFocus(tab_bar, tab);
 
-    // Drag and drop: re-order tabs
-    if (held && !tab_appearing && IsMouseDragging(0))
+    // Transfer active id window so the active id is not owned by the dock host (as StartMouseMovingWindow()
+    // will only do it on the drag). This allows FocusWindow() to be more conservative in how it clears active id.
+    if (held && docked_window && g.ActiveId == id && g.ActiveIdIsJustActivated)
+        g.ActiveIdWindow = docked_window;
+
+    // Drag and drop a single floating window node moves it
+    ImGuiDockNode* node = docked_window ? docked_window->DockNode : NULL;
+    const bool single_floating_window_node = node && node->IsFloatingNode() && (node->Windows.Size == 1);
+    if (held && single_floating_window_node && IsMouseDragging(0, 0.0f))
     {
-        if (!g.DragDropActive && (tab_bar->Flags & ImGuiTabBarFlags_Reorderable))
+        // Move
+        StartMouseMovingWindow(docked_window);
+    }
+    else if (held && !tab_appearing && IsMouseDragging(0))
+    {
+        // Drag and drop: re-order tabs
+        int drag_dir = 0;
+        float drag_distance_from_edge_x = 0.0f;
+        if (!g.DragDropActive && ((tab_bar->Flags & ImGuiTabBarFlags_Reorderable) || (docked_window != NULL)))
         {
             // While moving a tab it will jump on the other side of the mouse, so we also test for MouseDelta.x
             if (g.IO.MouseDelta.x < 0.0f && g.IO.MousePos.x < bb.Min.x)
             {
+                drag_dir = -1;
+                drag_distance_from_edge_x = bb.Min.x - g.IO.MousePos.x;
                 TabBarQueueReorderFromMousePos(tab_bar, tab, g.IO.MousePos);
             }
             else if (g.IO.MouseDelta.x > 0.0f && g.IO.MousePos.x > bb.Max.x)
             {
+                drag_dir = +1;
+                drag_distance_from_edge_x = g.IO.MousePos.x - bb.Max.x;
                 TabBarQueueReorderFromMousePos(tab_bar, tab, g.IO.MousePos);
             }
         }
+
+        // Extract a Dockable window out of it's tab bar
+        const bool can_undock = docked_window != NULL && !(docked_window->Flags & ImGuiWindowFlags_NoMove) && !(node->MergedFlags & ImGuiDockNodeFlags_NoUndocking);
+        if (can_undock)
+        {
+            // We use a variable threshold to distinguish dragging tabs within a tab bar and extracting them out of the tab bar
+            bool undocking_tab = (g.DragDropActive && g.DragDropPayload.SourceId == id);
+            if (!undocking_tab) //&& (!g.IO.ConfigDockingWithShift || g.IO.KeyShift)
+            {
+                float threshold_base = g.FontSize;
+                float threshold_x = (threshold_base * 2.2f);
+                float threshold_y = (threshold_base * 1.5f) + ImClamp((ImFabs(g.IO.MouseDragMaxDistanceAbs[0].x) - threshold_base * 2.0f) * 0.20f, 0.0f, threshold_base * 4.0f);
+                //GetForegroundDrawList()->AddRect(ImVec2(bb.Min.x - threshold_x, bb.Min.y - threshold_y), ImVec2(bb.Max.x + threshold_x, bb.Max.y + threshold_y), IM_COL32_WHITE); // [DEBUG]
+
+                float distance_from_edge_y = ImMax(bb.Min.y - g.IO.MousePos.y, g.IO.MousePos.y - bb.Max.y);
+                if (distance_from_edge_y >= threshold_y)
+                    undocking_tab = true;
+                if (drag_distance_from_edge_x > threshold_x)
+                    if ((drag_dir < 0 && TabBarGetTabOrder(tab_bar, tab) == 0) || (drag_dir > 0 && TabBarGetTabOrder(tab_bar, tab) == tab_bar->Tabs.Size - 1))
+                        undocking_tab = true;
+            }
+
+            if (undocking_tab)
+            {
+                // Undock
+                // FIXME: refactor to share more code with e.g. StartMouseMovingWindow
+                DockContextQueueUndockWindow(&g, docked_window);
+                g.MovingWindow = docked_window;
+                SetActiveID(g.MovingWindow->MoveId, g.MovingWindow);
+                g.ActiveIdClickOffset -= g.MovingWindow->Pos - bb.Min;
+                g.ActiveIdNoClearOnFocusLoss = true;
+                SetActiveIdUsingAllKeyboardKeys();
+            }
+        }
     }
 
 #if 0
@@ -10619,7 +10730,7 @@
             flags |= ImGuiTabItemFlags_NoCloseWithMiddleMouseButton;
 
         // Render tab label, process close button
-        const ImGuiID close_button_id = p_open ? GetIDWithSeed("#CLOSE", NULL, id) : 0;
+        const ImGuiID close_button_id = p_open ? GetIDWithSeed("#CLOSE", NULL, docked_window ? docked_window->ID : id) : 0;
         bool just_closed;
         bool text_clipped;
         TabItemLabelAndCloseButton(display_draw_list, bb, tab_just_unsaved ? (flags & ~ImGuiTabItemFlags_UnsavedDocument) : flags, tab_bar->FramePadding, label, id, close_button_id, tab_contents_visible, &just_closed, &text_clipped);
@@ -10629,6 +10740,11 @@
             TabBarCloseTab(tab_bar, tab);
         }
 
+        // Forward Hovered state so IsItemHovered() after Begin() can work (even though we are technically hovering our parent)
+        // That state is copied to window->DockTabItemStatusFlags by our caller.
+        if (docked_window && (hovered || g.HoveredId == close_button_id))
+            g.LastItemData.StatusFlags |= ImGuiItemStatusFlags_HoveredWindow;
+
         // Tooltip
         // (Won't work over the close button because ItemOverlap systems messes up with HoveredIdTimer-> seems ok)
         // (We test IsItemHovered() to discard e.g. when another item is active or drag and drop over the tab bar, which g.HoveredId ignores)
@@ -10664,6 +10780,16 @@
         if (ImGuiTabItem* tab = TabBarFindTabByID(tab_bar, tab_id))
             tab->WantClose = true; // Will be processed by next call to TabBarLayout()
     }
+    else if (ImGuiWindow* window = FindWindowByName(label))
+    {
+        if (window->DockIsActive)
+            if (ImGuiDockNode* node = window->DockNode)
+            {
+                ImGuiID tab_id = TabBarCalcTabID(node->TabBar, label, window);
+                TabBarRemoveTab(node->TabBar, tab_id);
+                window->DockTabWantClose = true;
+            }
+    }
 }
 
 ImVec2 ImGui::TabItemCalcSize(const char* label, bool has_close_button_or_unsaved_marker)
@@ -10678,10 +10804,9 @@
     return ImVec2(ImMin(size.x, TabBarCalcMaxTabWidth()), size.y);
 }
 
-ImVec2 ImGui::TabItemCalcSize(ImGuiWindow*)
+ImVec2 ImGui::TabItemCalcSize(ImGuiWindow* window)
 {
-    IM_ASSERT(0); // This function exists to facilitate merge with 'docking' branch.
-    return ImVec2(0.0f, 0.0f);
+    return TabItemCalcSize(window->Name, window->HasCloseButton || (window->Flags & ImGuiWindowFlags_UnsavedDocument));
 }
 
 void ImGui::TabItemBackground(ImDrawList* draw_list, const ImRect& bb, ImGuiTabItemFlags flags, ImU32 col)

diff --git a/misc/debuggers/imgui.natvis b/misc/debuggers/imgui.natvis
index 13b6360..94d17a8 100644
--- a/misc/debuggers/imgui.natvis
+++ b/misc/debuggers/imgui.natvis

@@ -55,4 +55,8 @@
   <DisplayString>{{Name {Name,s} Active {(Active||WasActive)?1:0,d} Child {(Flags &amp; 0x01000000)?1:0,d} Popup {(Flags &amp; 0x04000000)?1:0,d} Hidden {(Hidden)?1:0,d}}</DisplayString>
 </Type>
 
+<Type Name="ImGuiDockNode">
+  <DisplayString>{{ID {ID,x} Pos=({Pos.x,g} {Pos.y,g}) Size=({Size.x,g} {Size.y,g}) Parent {(ParentNode==0)?0:ParentNode->ID,x} Childs {(ChildNodes[0] != 0)+(ChildNodes[1] != 0)} Windows {Windows.Size}  }</DisplayString>
+</Type>
+
 </AutoVisualizer>