Comment 6 for bug 1128492

:~$ ls -al /usr/share/
drwxr-xr-x 3 root root 4096 mar 8 01:55 backgrounds

:~$ gsettings get org.gnome.desktop.background picture-uri
'file:///usr/share/backgrounds/warty-final-ubuntu.png'

:~$ dbus-send --print-reply --system --dest="org.freedesktop.Accounts" /org/freedesktop/Accounts/User1000 org.freedesktop.DBus.Properties.Get string:"org.freedesktop.Accounts.User" string:"BackgroundFile"

method return sender=:1.77 -> dest=:1.188 reply_serial=2 variant string "/usr/share/backgrounds/Vanishing_by_James_Wilson.jpg"

Background was stuck on "Vanishing_by...." set in 12.10 some time ago. After upgrade noticed that the unity-greeter version of the background (i.e. with password box) transferred to desktop background (i.e. it had the password box). Was not possible to set another background via system-settings. Using dconf -editor I got it to disappear from the desktop but not the greeter; desktop however now blank.