I experienced a regression in Qt 6.10: applications that use QMainWindow are partially off-screen if no initial geometry is set.

Before Qt 6.10, these windows were positioned to the top left corner. Since Qt 6.10, the content of the window is positioned to the top left corner, and the window frame (the titlebar) is completely outside of the screen.

Many window managers like KWin, Metacity, Xfwm4 force the windows to be placed within the screen, so this issue cannot be seen, but some window managers like Openbox and IceWM don't have such logic. I think Qt should not request the window to be placed at 0,0 if no initial position is set by the application.

This can be reproduced by running a very basic program in Openbox: main.c