Cannot expand preferences window
In my preferences window I no longer have the three tabs in the upper left corner. I have only the close tab with the red "X" and the minimize tab with the "-". The third tab with the square is no longer there and I cannot maximize my preferences window. I am using Ubuntu 12.10
Alla svar (2)
Use Restore or Maximize in the right-click context menu of the Taskbar icon to set focus to the Firefox application if you do not see it.
Open the system menu via Alt+Space and see if you can resize that window.
If that works then close Firefox (File > Exit/Quit) to save that setting.
See also:
http://kb.mozillazine.org/Resizing_oversize_window
If the above didn't help then see:
http://kb.mozillazine.org/Corrupt_localstore.rdf
Did you try if it is possible to resize that window by dragging the corner at the bottom right?