This patch tries - and fails - to fix the flicker of screens while
the kscreenlocker_greeter is active. The reasoning of the patch is
instead of deleting the overlays in the vector untill we have as
many overlays as screens, we check if a overlay belongs to a screen
that's currently plugged in, deleting only those that don't have
a screen anymore.
and then, instead of going thru all of the views and updating the
geometry and position, we only set that once for each overlay created.
This is not by all means something that I want to merge, as currently
is broken, but given the current implementation is also broken I think
it's safe to assume a 'v1' so we can discuss what's wrong on both
To test the bug: plug two monitors, run the locker, detach and reattach
the monitors. on detaching (but not reattaching) the monitor will flicker
and display the contents of what's behind the locked screen.