Comments

backends/imgui_impl_sdl2.cpp

@@ -676,6 +676,7 @@ static void ImGui_ImplSDL2_UpdateMouseData()
             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.
         SDL_Window* hovered_window = SDL_GetMouseFocus();
         const bool is_relative_mouse_mode = SDL_GetRelativeMouseMode() != 0;
         if (hovered_window == NULL && bd->MouseCanUseGlobalState && bd->MouseButtonsDown == 0 && !is_relative_mouse_mode)

backends/imgui_impl_sdl3.cpp

@@ -638,6 +638,7 @@ static void ImGui_ImplSDL3_UpdateMouseData()
             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.
         SDL_Window* hovered_window = SDL_GetMouseFocus();
         const bool is_relative_mouse_mode = SDL_GetWindowRelativeMouseMode(bd->Window);
         if (hovered_window == NULL && bd->MouseCanUseGlobalState && bd->MouseButtonsDown == 0 && !is_relative_mouse_mode)

docs/CHANGELOG.txt

@@ -60,6 +60,7 @@ Other Changes:
 - Backends: SDL2,SDL3: avoid using the SDL_GetGlobalMouseState() path when one of our
   window is hovered, as the event data is reliable and enough in this case.
   - Fix mouse coordinates issue in fullscreen apps with macOS notch. (#7919, #7786)
+    - Essentially a working for SDL3 bug which will be fixed in SDL 3.3.0.
   - Better perf on X11 as querying global position requires a round trip to X11 server.
 - Backends: Win32: minor optimization not submitting gamepad io again if
   XInput's dwPacketNumber has not changed. (#8556) [@MidTerm-CN]