Multi-monitor broken for me in gnome & unity

[Justin Hart]

The title says most of what I know about my issue.  I start Gnome or
Unity, and I get one screen with my desktop background, and working
UI, the others give me the classic x-org plain background and the X
cursor.

Current X config is as follows.  4 monitors, configured using
nvidia-settings, no twinview, no xinerama, absolute positioning, and
the positions are all set up from left-to-right with no overlap.

Justin