config file for "Spanning Desktops" feature

["Toby McMillan, RHCE" <toby mcmillan gmail com>]

Hello everyone!

Where do I find the config file for "Spanning Desktops" feature? I
have configured a dual head display for an LTSP thin client and I
would want to the desktop to span across the two monitors (instead of
the default "Individual Desktops" setting). I'm using CentOS.

Can this be configured in xorg.conf?If not, where? Thanks in advance
for any tips. :-)