Ctrl-Alt-L works here when menus are open. The idle timeout also blanks and locks the screen when menus are open and pressing a key unblanks the screen to reveal the lockscreen which cannot be bypassed by further keypresses or mouseclicks.
Ubuntu 14.04.2 LTS. unity 7.2.5+14.04.20150603-0ubuntu1
Ctrl-Alt-L works here when menus are open. The idle timeout also blanks and locks the screen when menus are open and pressing a key unblanks the screen to reveal the lockscreen which cannot be bypassed by further keypresses or mouseclicks.
Ubuntu 14.04.2 LTS. 04.20150603- 0ubuntu1
unity 7.2.5+14.