[TriLUG] xrandr + software cursor

[Brian via TriLUG]

Hi y'all,

I'm (again) banging my head against multi-head config of my Linux 
workstation.  I had been ticking along using Xinerama to get the "single 
desktop" feel (e.g. able to drag windows between monitors on physically 
separate adapters), but that came at a cost of no 3D acceleration.

Enter xrandr.  After some poking about, I learned how to use no 
xorg.conf file at all, then issue commands to xrandr to activate the 
displays I want.  All well and good; I get my "single desktop" feel and 
I also get hardware 3D.

Now enter FreeCAD (and some other mouse-cursor-manipulating 
applications).  When an application uses a custom mouse cursor, the 
cursor appears corrupted (appearing as a block of random pixels, or a 
black block, etc.).

I did more googling and learned that a common solution to the corrupted 
mouse cursor issue is to turn on "software cursor".  To do that, one 
modifies the Device SubSections of xorg.conf to include...oops.  Wait! 
I don't have an xorg.conf!

The particular sticking point is that if I do have an xorg.conf file 
with Device subsections, xrandr is only able to see one adapter.

Does anyone know of a solution to this?  I seem to have overreached my 
Google-fu at this point.

Thanks!
-Brian