themes - Why is my desktop background black after upgrade to 13.04?

After I upgraded to 13.04 my desktop background has been a black screen, i.e.:

EDITS: Ubuntu tweak doesn't seem to be able to change the window theme either (although all other themes like icon themes are all easily modifiable). Tweak tool can change the window theme, however.

I have tried the following:

• Changing desktop backgrounds (including back to default)


• Rebooting


• Running the commands in terminal:
  (Which were obtained from the answer to the question, Unity does not start in Ubuntu 13.04)

dconf reset -f /org/compiz/
&& unity --reset-icons &disown

and then rebooting (which just changed the colour and size of the unity launcher)

The following line pasted into a terminal did recover the background image for me:

gsettings set org.gnome.settings-daemon.plugins.background active true

Hope that helps you too...