I haven't tried using those other window managers, a patch would be welcome. Gnome/Kde users have reported no such issues... All OIS does for an alt-tab in Linux is detect it, and ungrab input (mouse/keyboard). When the window is clicked on again, it will detect that and re-capture the mouse / keyboard. I suspect some x11 message is being garbled by those other window managers that do not let OIS know it is time to recapture input.