Merge branch 'master' into docking

# Conflicts:
#	backends/imgui_impl_dx12.cpp
#	backends/imgui_impl_vulkan.cpp

imgui.cpp

@@ -1,4 +1,4 @@
-// dear imgui, v1.91.7
+// dear imgui, v1.91.8 WIP
 // (main code and documentation)
 
 // Help:
@@ -5269,6 +5269,7 @@ void ImGui::UpdateHoveredWindowAndCaptureFlags()
 }
 
 // Called once a frame. Followed by SetCurrentFont() which sets up the remaining data.
+// FIXME-VIEWPORT: the concept of a single ClipRectFullscreen is not ideal!
 static void SetupDrawListSharedData()
 {
     ImGuiContext& g = *GImGui;