There's logic in Qt that uses xcb_set_input_focus to focus parent windows as some X11 window managers ignore such focus requests leaving the parent activated, but without input focus. By the time delayed activation happens, current focus window may no more exist and the logic in Qt won't work. X11BypassWindowManagerHint says Qt it should use xcb_set_input_focus on X11 that asks X11 directly to set input focus to that window.
