osk should not set exclusive zone when e.g. used on the shell
for e.g. phosh!344 (closed) it would be great if the keyboard would not set an exclusive zone but rather pop up on top of the shell's overview surface reducing flickerung and content movement.
this might be useful for other application's as well where we're sure no vital part of the ui can be hidden by the keyboard.
i'm mostly filing this so we get a more complete view about compositor / shell / osk ineraction .