I upgraded Ubuntu 12.04 to 12.10. I use Gnome shell. Gnome 3.6 is working fine, but there are no applications menus. I have tried several suggestions I found online, but I can'g get the menus back. When I click "Activities" I just get a blank page.
After removing all extensions, I now have an icon on the dock that shows all applications.
I've made custom Ubuntu with Ubuntu builder. I've installed gnome-shell and cairo-dock from chroot. I've removed Unity from chroot too.
I've edited /etc/lightdm/lightdm.conf, changed user-session = cairo-dock and then I built the custom ubuntu. I then ran it on virtual box. LiveCD successfully showed the Cairo dock but when I change to user-session = gnome-shell, desktop shows unity panel.