Revert "Redo the region z-index, use an extra group for sub regions and use clutter_actor_set_depth"
This reverts commit
abff6d6fe0cf27acc6bf3de4485450a5f74d9dbe.
I noticed that depth is really a 3D param and regions grow when bringing them
to front.
According to the clutter code, raise only changes the actor in the children list. So
the sorting could be a bit smarter.
To fix the problem of sub regions appearing under parent region media type users,
monitor the actor-added signal and raise the actor wrt. to the background actor.
Conflicts: