Bug xorg-server 1.1 (exa enabled) and xscreensaver

[Gregoire Gentil]

Hello,

I have a strange bug which is the following:

Configuration:
Gentoo 2006 distribution
xorg-server 1.1.1 (I have Option	"AccelMethod"	"exa")
Openchrome (svn revision 200) for a VIA video card
Xscreensaver 4.24
xfce 4.4 beta 2

Behavior:
When compositing is enabled, after xscreensaver has run a screen saver,
when it returns to the desktop after an event, everything stays black.
It's not totally dead as faking quitting enables to get back the screen
but the windows can't be moved and refresh doesn't work. The session is
not totally dead but xorg is not responsive.
It's the same problem after previewing a screensaver and going back to
the desktop. Last, if compositing is disabled in the window manager,
there is no such problem.

Questions:
-1. Has anyone experienced this problem? Especially with another video
driver? I would like to understand where the problem is (xscreensaver,
xorg-server, video driver, desktop/window manager = xfce). I suspect
xorg but perhaps I'm wrong.
-2. How could I debug the situation? Xorg log doesn't provide anything
useful information.

Many thanks for any tip around this problem,

Gregoire