Layout info (imgui.ini) improperly saved with multiple windows

[vid512]

With the example/multiple_windows, it seems each SFML window keeps track only of its own ImGui windows layout. Upon saving ImGui window layout (imgui.ini), it resets other windows' values to original values.

For example: When you move/resize ImGui window inside the child SFML window and close it, the new layout is saved to imgui.ini. Then, when you close the main window, child window layout gets resetted back to the original values. Layout changes done to the child window are ultimately not saved. See attached video.

https://github.com/user-attachments/assets/85ed53fb-02df-4262-91ce-00e6072e2458