After upgrading from xfwm4 4.13.1 to 4.13.2, Qt's QWindow::lower() function no longer works for maximized windows. Under the hood, QWindow::lower() calls XCB_CONFIG_WINDOW_STACK_MODE with XCB_STACK_MODE_BELOW . Apparently this request is now ignored by xfwm4 when the target window is maximized.
git bisect says "3751c2c716714f84dd3d527b60f3543e96fac54e is the first bad commit".
Steps to reproduce:
1. git clone https://gitlab.com/yan12125/test-lower
2. cmake .
5. Hit the "Run lower()" button and check if the window is lowered
6. Maximized the window and repeat step 5. This time the window is _not_ lowered.
Environment: Arch Linux, Qt 5.12.4
Olivier Fourdan referenced this bugreport in commit d8435e5e462f8e1acd2d7a5d085dab9b851ebe8f
Revert "events: ignore client configure requests when maxized"