Comment 3 for bug 351491

Primary monitor support has improved, both in gnome-panel and in unity, and it can now be configured in the gnome-display-properties applet, which should take care of the underlying issues described here.

The issue of having the applet functionality available from the desktop context menu seems to have improved. When you launch the background settings dialog there is now a 'All Settings' button on the top, which takes you to a page of multiple configuration utilities including the one for 'Displays'.

So I think this can be closed. A lot has changed with the introduction of Unity though, so it's worth re-examining this workflow again in light of that and filing new bugs (against unity) if there are still issues.