How to set modeline under xorg server 1.8.0

[Another Sillyname]

On 11 June 2010 02:26, Another Sillyname <anothersname at googlemail.com> wrote:
> Hi
>
> I have a setup which I've just upgraded to Fedora 13 with Xorg server
> 1.8.0.  The setup has a Quadro FX 3400 card with an IBM T221 3840 x
> 2400 monitor.
>
> Under previous iterations of xorg i've output to the monitor as a
> dualhead setup using 1920x2400 + 1920x2400 and it's worked pretty
> well.
>
> However under the new version of Fedora the xorg.conf file now gets
> re-generated every reboot using udev to detect devices if I've
> understood the docs properly.
>
> Unfortunately the display is getting detected as a 3840x2400 screen
> and is being output to at the wrong refresh rate, 50 hz rather then 25
> hz, at least according to xrandr -q, and as a result the screen is
> blank.  The xorg session is running however as I can vnc into it and
> it's running fine.  I am using the nvidia driver from rpmfusion.
>
> Given that xorg.conf is re-written every reboot how can I add both a
> modeline and dualhead type config so that it 'sticks' after a reboot?
>
> Thanks in advance.
>

As a follow up to my earlier mail I've found that you can now put the
xorg.conf in /etc/X11/xorg.conf.d and it will get read from there so
that's solved that problem.

My new problem is slightly different in that as the display is treated
as two screens how do I get the screen background and panels to spread
across as a single screen?

i.e. at the moment my desktop background is shown as two identical
images one on each screen, what I want is one background image spread
across both screens.  Also any panels are limited to one screen rather
then being spread across both screens.

I know ATI had a concept called 'Big Desktop' for these situations but
I could never get it working, does anyone have any ideas or
workarounds to get it working now with an NVidia card?

Thanks in advance.