I am more recently or mainly in my GTK4 application find that key board accelerator as assigned to a window are been mixed up with other window(s) or not functional unless I multiple times hit the key or do any other like menu interactions to get this window some what responding – even the window received visually the focus already by the WM.
Using X11.
Using “sloppy focus follow mouse” mode.
Never happens with GTK3 based older version of the app.