I am currently a technology coordinator in my school in the Bronx, USA. I have 22 desktops in a computer lab running Edubuntu 12.04 32-bit. I want to prevent these students (standard user) from being able to change the desktop background.
I tried installing and using gconf-editor and going to gnome>desktop>background and right clicking on the background image key, clicking "Set as Mandatory" and entering the admin password. There was no indication it went through, and even after a system reboot, I could change the background simply by right clicking on the desktop, choosing "change desktop background" and clicking on any other image.
What am I doing wrong?!? Please help!