Disable native titlebar while lacking enough space for SM_CYCAPTION.
On Windows, applications can disable titlebar by extending the client rect to a bigger rect which will cover the area of the titlebar from WM_NCCALCSIZE: https://learn.microsoft.com/en-us/windows/win32/dwm/customframe#removing-the-standard-frame Our current x11 and Mac driver doesn't handle this case.
Attached is a test case for reproducing the issue.
Edited by Jactry Zeng