help with dual-head OpenGL? [was: Woody + mesag3 + xinerama = problem]

[Mike Pfleger <pfleger@pfleger-precision.com>]

I find it hard to believe that nobody else on the list has seen this
problem.  I had GL working on both displays in xinerama when Woody was
still testing, but my latest install only has GL working on display 0.
This can be verified with the GL screensavers, as detailed below, but
it affects real applications that I try to run with xinerama.  All of
my searching for documented solutions have proved fruitless.

I'm at a complete loss as to where to begin with this.  The fact that
it used to work suggests that there's a configuration issue...

Any help is greatly appreciated.

> I've discovered that the GL screensavers, when spawned in Xinerama,
> only appear on display 0 leaving display 1 blank.  This seems like
> too great of a coincidence, then, that Blender also only renders its
> workspace on display 0, with an empty portion of the window frame
> rendered on display 1.
> 
> On the Blender mailing list it was suggested that, although the display
> seems to work fine without Xinerama, GL is not enabled for the second
> head in Xinerama.  How is this possible?  Is there something that needs
> to be done to enable GL for the second head?  This used to work on the
> old install of Woody (both Blender and xscreensaver-gl), so I'm really
> at a loss.  Both of my cards are ATI Mach64, btw.
> 
> Oh, and I sometimes get an error message when demo-ing the screensavers
> to the effect of:
> 	xscreensaver window unexpectedly deleted.
> -I'm hoping that means more to someone than it does to me.

Thanks in advance,
Mike Pfleger
pfleger@pfleger-precision.com
(250) 479-0321