[compiz] Misc WM buglets

[Mike Hearn]

Switching viewports/desktops/cube faces seems to mess up the stacking 
order - Quinn Storm says the visible stacking order isn't reflected 
somewhere else.

Bottommost windows don't seem to work right - not sure if this is a bug 
in compiz or gimmie but Gimmies button bar never drops below maximized 
windows and it does in Metacity. Will investigate when I get a chance.

thanks -mike