"mouse gives focus to hovered window" issue when another window is fullscreened (F11)

[JLuc]

When some window has been fullscreened (F11, no menubar nor titlebar)
then the "focus is given to window under mouse pointer" is broken :
it brings the fullscreened window on top, even if it should stay behind some other new window.

Steps to reproduce
- open unity tweak, go to "Windows management" tab > "More" (last subpane)
(my UI is french so i'm unsure with english labels)
- choose "Focus" > "Autoraise" + choose "Sloppy"
- open Firefox (for example)
- press F11 to make it full screen
- open any other app (geany or libreoffice for example)
- bring mouse on center of this new window
- See : Firefox is brought to front and other app window disappear in the back.

On Ubuntu 14.04