Description of problem:
Right now we check the visual to see if we use shaped or compsite windows but if
we have an ARGB visual but no comp manager running we get an ugly black box
where it should be transparent.
  
How to fix:

Check to see if an XSelection has been grabed by a comp manager.  If so then use
composite, if not, use shaped windows.  This should be dynamic.  If the
selection goes away, start shaping the window.  If a new comp manager grabs the
selection start using composite.  This involves simply flipping a switch in the
eggnotificationbubble instance struct (I think it is has_composite or do_composite).

Standerdize on some name like X_COMP_MANAGER_ACTIVE