AIGLX - fullscreen off-center

[Dan B. Phung]

I'm getting wierd behavior when running 3d games over AIGLX, and the 
only difference that I see is in the authentication, which seems 
unrelated. 

My setup is an application node hosts the game and sends rendering data 
to the display node.  I can send my xorg.conf, but I doubt that's 
helpful right now.  My driver on the display node is the i915 intel 
driver. 

IOQuake 3
- using ssh/X forwarding, everything is fine.
- when I authenticate using xauth, the fullscreen is off-center.  if I 
then try X forwarding through ssh, the screen is centered correctly 
through the ssh forwarded socket and, when I logout of the ssh connect, 
the X forwarding over xauth is also centered correctly.  wierdo....

The symptoms are the same for Tremulous, but this time instead of being 
off-center, the screen is simply not full-screen (it's about 2/3 of the 
full-screen).  If I do the ssh-thing, then this also "fixes" the full 
screen for the xauth authenticated forwarding.  The only other info I 
can think of to post is the xrandr info:

Screen 0: minimum 320 x 200, current 1024 x 768, maximum 1280 x 1280
VGA disconnected (normal left inverted right)
LVDS connected 1024x768+0+0 (normal left inverted right) 286mm x 178mm
   1280x800       59.9 +   60.0 
   1280x768       60.0 
   1024x768       60.0*
   800x600        60.3 
   640x480        59.9 

which is the same for both "non-centered" and "centered" sessions.

Can somebody point me in the right direction to look?  I don't mind 
looking into mesa/ intel driver code.

thanks,
dan