Bug#590121: Same problem, appears to be due to xinerama

[Chuck Williams]

I'm having the same problem.  It appears to be due to using Xinerama 
(cause of no randr), which is still necessary to support a single 
virtual display spanning multiple monitors each driven by a different 
video device.

I tried to get a stack trace, but gnome locks up while in gdb at 
breakpoint in gdk_x_error and I'm not sure how to work around that 
(tried from console virtual terminal, but gnome-screensaver won't run 
from there because it can't get the display).

I'm using the radeon driver.

Has anybody gotten gnome-screensaver to work with Xinerama?