Composite use in GNOME causes a strange behavior

[Carlos Eduardo Rodrigues Diogenes <cerdiogenes yahoo com br>]

Hi,

I was testing some softwares that use composite, while running GNOME, 
like xcompmgr and mouseloupe 
(http://www.inf.ufpr.br/imago/mouseloupe/english/index.html) and I 
percepted that when is asked to redirect all the windows to off-screen 
and when they are composed to be showed to the user the panel lost the 
power to force windows to stay under it, so the windows can be moved 
freely to where you want.

Why this happen? This is why the window manager used by gnome don't 
expect to have a composite manager or other applications that use this 
extension?

Thanks,
Carlos.