Backends: GLFW, SDL: report Windows key (io.KeySuper) as always released.

Neither GLFW nor SDL can correctly report the key release in every cases (e.g. when using Win+V) causing problems with some widgets. The next release of GLFW (3.4+) will have a fix for it. However since it is both difficult and discouraged to make use of this key for Windows application anyway, we just hide it. (#2976)
diff --git a/docs/CHANGELOG.txt b/docs/CHANGELOG.txt
index a3e0331..11afd5e 100644
--- a/docs/CHANGELOG.txt
+++ b/docs/CHANGELOG.txt
@@ -84,12 +84,14 @@
 - Backends: GLFW: Added support for the missing mouse cursors newly added in GLFW 3.4+. [@rokups]
 - Backends: SDL: Wayland: use SDL_GetMouseState (because there is no global mouse state available
   on Wayland). (#2800, #2802) [@NeroBurner]
+- Backends: GLFW, SDL: report Windows key (io.KeySuper) as always released. Neither GLFW nor SDL can
+  correctly report the key release in every cases (e.g. when using Win+V) causing problems with some
+  widgets. The next release of GLFW (3.4+) will have a fix for it. However since it is both difficult
+  and discouraged to make use of this key for Windows application anyway, we just hide it. (#2976)
 - Backends: Win32: Added support for #define IMGUI_IMPL_WIN32_DISABLE_GAMEPAD to disable all
   XInput using code, and IMGUI_IMPL_WIN32_DISABLE_LINKING_XINPUT to disable linking with XInput,
   the later may be problematic if compiling with recent Windows SDK and you want your app to run
   on Windows 7. You can instead try linking with Xinput9_1_0.lib instead. (#2716)
-- Backends: Win32: Added support for io.KeySuper (Windows key) for consistency with other backends,
-  even if realistically it is difficult to make good use of under Windows.
 - CI: Added PVS-Studio static analysis on the continuous-integration server. [@rokups]
 - Examples: Explicitly adding -DIMGUI_IMPL_OPENGL_LOADER_GL3W to Makefile to match linking
   settings (otherwise if another loader such as Glew is accessible, the OpenGL3 backend might
diff --git a/examples/imgui_impl_glfw.cpp b/examples/imgui_impl_glfw.cpp
index 2182efb..c496232 100644
--- a/examples/imgui_impl_glfw.cpp
+++ b/examples/imgui_impl_glfw.cpp
@@ -122,7 +122,11 @@
     io.KeyCtrl = io.KeysDown[GLFW_KEY_LEFT_CONTROL] || io.KeysDown[GLFW_KEY_RIGHT_CONTROL];
     io.KeyShift = io.KeysDown[GLFW_KEY_LEFT_SHIFT] || io.KeysDown[GLFW_KEY_RIGHT_SHIFT];
     io.KeyAlt = io.KeysDown[GLFW_KEY_LEFT_ALT] || io.KeysDown[GLFW_KEY_RIGHT_ALT];
+#ifdef _WIN32
+    io.KeySuper = false;
+#else
     io.KeySuper = io.KeysDown[GLFW_KEY_LEFT_SUPER] || io.KeysDown[GLFW_KEY_RIGHT_SUPER];
+#endif
 }
 
 void ImGui_ImplGlfw_CharCallback(GLFWwindow* window, unsigned int c)
diff --git a/examples/imgui_impl_sdl.cpp b/examples/imgui_impl_sdl.cpp
index 8a295aa..32722bf 100644
--- a/examples/imgui_impl_sdl.cpp
+++ b/examples/imgui_impl_sdl.cpp
@@ -115,7 +115,11 @@
             io.KeyShift = ((SDL_GetModState() & KMOD_SHIFT) != 0);
             io.KeyCtrl = ((SDL_GetModState() & KMOD_CTRL) != 0);
             io.KeyAlt = ((SDL_GetModState() & KMOD_ALT) != 0);
+#ifdef _WIN32
+            io.KeySuper = false;
+#else
             io.KeySuper = ((SDL_GetModState() & KMOD_GUI) != 0);
+#endif
             return true;
         }
     }
diff --git a/examples/imgui_impl_win32.cpp b/examples/imgui_impl_win32.cpp
index 189f6d3..140e1e4 100644
--- a/examples/imgui_impl_win32.cpp
+++ b/examples/imgui_impl_win32.cpp
@@ -28,7 +28,6 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
-//  2020-01-17: Inputs: Added support for io.KeySuper (Windows key) for consistency with other backends, even if realistically it is difficult to make good use of under Windows.
 //  2020-01-14: Inputs: Added support for #define IMGUI_IMPL_WIN32_DISABLE_GAMEPAD/IMGUI_IMPL_WIN32_DISABLE_LINKING_XINPUT.
 //  2019-12-05: Inputs: Added support for ImGuiMouseCursor_NotAllowed mouse cursor.
 //  2019-05-11: Inputs: Don't filter value from WM_CHAR before calling AddInputCharacter().
@@ -230,7 +229,7 @@
     io.KeyCtrl = (::GetKeyState(VK_CONTROL) & 0x8000) != 0;
     io.KeyShift = (::GetKeyState(VK_SHIFT) & 0x8000) != 0;
     io.KeyAlt = (::GetKeyState(VK_MENU) & 0x8000) != 0;
-    io.KeySuper = ((::GetKeyState(VK_LWIN) | ::GetKeyState(VK_RWIN)) & 0x8000) != 0;
+    io.KeySuper = false;
     // io.KeysDown[], io.MousePos, io.MouseDown[], io.MouseWheel: filled by the WndProc handler below.
 
     // Update OS mouse position