Comment # 5 on bug 1150675 from Tam�s N�meth

(In reply to Stefan Dirsch from comment #4)
> Ok. Since you were mentioning XFCE and Display compositing"  is its default
> that was my first idea. Unfortunately driver regressions are always possible
> and the older the hardware the more unlikely it is, that these get fixed
> again. :-( You may want to give Mesa's environment variable
> a try
> 
>  LIBGL_ALWAYS_SOFTWARE=true

Well, I didn't even know that XFCE's window manager does compositing. You're
right, it's the default, but I didn't notice it because it doesn't do any
Compiz-like trick. However, I enabled some transparency in window handling, and
I noticed that xfwm4 uses openGL indeed, but it runs very smoothly and without
any gliches. Then I tried glxgears, which also ran with high FPS and without
any problem, even when xfwm4 made it transparent.

So 3D rendering is not entirely broken, only some functions of it, and the
problem seems not to be in the kernel. The attached gmail glitch for example
also occurs with windows compositing disabled.

I'm afraid it's an upstream bug either in the X server or in Mesa. Thank you
for the informations.