[gdm-list] Multiple monitor issues w/ GDM 2.28

[Lawrence Statton <lawrence cluon com>]

I'm having some issues getting my multi-headed configuration working.  
I'm migrating from a failed Sun E2 to PC hardware running Linux.

I am trying to get a single display configured with three screens.  (I 
use the words 'screen' and 'display' in their X meanings  - that is:  
One X server at :0 is handling three screens :0.0, :0.1 and :0.2 )

I've gotten to the point where I have X driving two of the three 
monitors (after buying 4 different frame buffers) but I only get useful 
behavior on one of the monitors ( I suspect very strongly I can get the 
three-headed X server going - all signs are pointing to "yes" but the 
3rd display is temporarily in use by another person here )

OS is recent Ubuntu (10.04 LTS) and thus far everything is stock out of 
the box *except* that I've
got a custom xorg.conf

I've got two frame buffers -- one is a Radeon Dual-VGA PCI card (9000 
series, I don't have the exact part number at hand) which is driving the 
'less useful' monitor

The computer has video on the motherboard (it's an IBM/Lenovo 
ThinkCentre - Intel 915G chipset) which is driving the 'more useful' 
monitor.

The machine boots and the 'mostly purple' Ubuntu root-window graphics 
appear on *each* screen, but only one of them has any "real activity" 
(that is:  When I log in, there are only window-manager decorations in 
the :0.0 screen, only the :0.0 screen responds to clicks in the 
root-window) ... I can mouse over to the other screen and see the pointer.

If I try launching an X client (e.g. xterm -display :0.1 ) "nothing 
appears to happen" ( no error returned, but neither does a terminal 
launch ) (nb I also tried launching the xterm as root, in case there 
were some permission issues )

The release notes mention that  "GDM 2.20 and earlier supported the 
ability to manage multiple displays with separate graphics cards" and 
"These features were not added back during the 2.22 rewrite."

The question looming large in my mind is:  Are they using the words 
"multiple displays" in the pedestrian sense of "many things on my desk" 
or in the specific X sense of the word "a group of screens bound to a 
keyboard and mouse"?

Can gdm/gnome be made to do what I want, or am I going to just have to 
continue using xdm/fvwm like I have been for the last 15 years?

--L