I am on Ubuntu 12.10 with Unity shell. I am not quite sure what happened, but today I noticed that the menubar (containing 'File, Edit, etc...') is not appearing on the panel as it used to (i.e. the global application menu), but on the application window under the title bar. The only application that still uses global menu is Chromium. Any ideas what settings may have changed?

Also, when I right click on the desktop and select "Change Desktop Background", System Settings opens, instead of the "Appearance" settings.

Apparently, here is a related question, with no answer: Global menu and HUD suddenly broken

EDIT: I noticed this behavior on three of my computers after an update (I do not remember exactly which packages were updated). Now when I try to run apt-get upgrade, I get:

The following packages have been kept back: gnome-control-center gnome-control-center-data

I guess something is going on with updates. Any info would be appreciated.