Description of problem:
Update to version 2.28.2 broke spanning a single background across multiple monitors.

(release announcment http://www.mail-archive.com/fedora-package-announce@redhat.com/msg33288.html )
Specifically gnome bug https://bugzilla.gnome.org/show_bug.cgi?id=147808

Version-Release number of selected component (if applicable):
2.28.2-1.fc12

How reproducible:
every time.

Steps to Reproduce:
1. Use pre-2.28.2 gnome-desktop package
2. set a WIDE background image (like the wide-screen lion image from F11)
3. ooh and aah over it spreading across multiple screens
4. upgrade to 2.28.2-1fc12.
5. log out and back in
6. go "WHAT!?!?!?" as you notice the image is not spanned across the monitors but displayed twice... once on each monitor.
  
Actual results:
the image is "squished" once per monitor instead of spanning across both.

Expected results:
the image to span across both monitors as it did previously

Additional info:
Suggest add an option to toggle weather monitor spanning should be done.

Workaround:
The only workaround I have it to tell nautilus to NOT control the desktop (gconf setting /apps/nautilus/preferences/show_desktop set to false). and then use compiz to set the background (via wallpaper plugin).. however this has the problem of loosing all icons on the desktop.