[Feature request] Set wallpaper for gnome-screensaver lock

[Oleg O Andreev]

Currently Ubuntu-tweak supports customizing only the GDM background, leaving the gnome-screensaver unlock dialog with the black background. This looks rather inconsistent and many users desire to change this background to match the GDM background.

The attached patch adds an option to "Login screen" page to select and set background for unlock dialog in gnome-screensaver. Login screen seems to be the best place to add this option because:
 * users would most likely want to match the lock screen background to login screen background;
 * currently the only way to apply this change (apart from killing gconfd-2) is to restart user session anyway.

[Ding Zhou (tualatrix)]

Thanks.

I will try to merge this patch to the developing version of Ubuntu Tweak 0.6.