Make classes not depend on the implicit GImGui context (#6199, #5856, #6199): ImGuiIO
This commit is a preparation toward adding ImGui apis with explicit context
and making ImGui applications being able to use multiple context at the same time
whatever their concurrency model.
About ImGuiIO:
- ImGuiIO depends on ImGuiContext because some of its method want to event to `g.InputEventQueue`.
- To make ImGuiIO aware of the context to use, context which creates the ImGuiIO is given as argument of ImGuiIO constructor.
- The assert `IM_ASSERT(&g.IO == this && "Can only add events to current context.")` has been removed since it does not make sense anymore
NOTE: ImGuiIO could be completely independent of ImGuiContext if the InputEventQueue was moved from ImGuiContext to ImGuiIO, but since
ImGuiIO is a public class it would expose InputEvent type. Solving this problem is out of the current scope, but it is interesting to notice.
4 files changed
