In order to properly track the stacking order for override-redirect
windows, move meta_compositor_sync_stack() call into MetaStackTracker.
In the new location, we sync the stack as a before-redraw idle function,
rather then using the freeze-thaw facilities of MetaStack. This is
simpler, and also properly compresses multiple stack changes on
notifications received from the X server.
http://bugzilla.gnome.org/show_bug.cgi?id=585984
Wedging override-redirect windows into the constraint code in stack.c
results in Mutter getting confused about the stacking order of
these windows with respect to other windows, and may also in some
cases cause Mutter to restack override-redirect windows.
core/stack-tracker.c core/stack-tracker.h: MetaStackTracker - combine
events received from the X server with local changes we have made
to come up with the best possible idea of what the stacking order
is at any one point in time.
core/screen.c core/screen-private.h: Create a MetaStackTracker for
the screen.
core/display.c: Feed relevant events to MetaStackTracker
core/frame.c core/screen.c core/stack.c: When we make changes to the
stacking order or add windows, record those changes immediatley
in MetaStackTracker so we have the information without waiting
for a round-trip.
include/ui.h ui/ui.c: meta_ui_create_frame_window add a return value
for the X request serial used to create the window.
http://bugzilla.gnome.org/show_bug.cgi?id=585984
