Same problem. New install of 16.04.1.
$ gedit --> shows menu
$ sudo gedit --> does NOT show menu
$ gksudo gedit --> does NOT show menu
$ sudo -i ... # gedit --> does NOT show menu
This happens whether the menus are set for the title bar OR for the top of the screen.
Tried reinstalling gedit. No difference.
Same problem. New install of 16.04.1.
$ gedit --> shows menu
$ sudo gedit --> does NOT show menu
$ gksudo gedit --> does NOT show menu
$ sudo -i ... # gedit --> does NOT show menu
This happens whether the menus are set for the title bar OR for the top of the screen.
Tried reinstalling gedit. No difference.