Possible Duplicate:
How to restrict users on changing their wallpapers?
I'm trying to lock the desktop background (So, that it cannot be changed by others) but can not find the way, I got it in 10.04 with "gconf-editor", but now I can not do this in 12.04
Besides the list of solutions which can answer your question which can be found to this similar question.
Another way to achieve that is the following:
Open terminal and login as root:
sudo -i
Type:
chmod 744 /usr/bin/ gnome-appearance-properties
To restore:
chmod 755 /usr/bin/gnome-appearance-properties
