I have a problem with my Ubuntu, running 14.04 LTS.
The problem is that I'm trying to user Alt+F4 and Alt+Tab and it doesn't work, it only works with the Right Alt.
I also tried to set a new keyboard short-cut for Alt+F4 and Alt+Tab but as soon as I press Alt the short-cut is set.
The thing I noticed once I set the shortcut is that the key didn't correspond with Alt, it was a Level3 Shift.
I search all over the internet of a method to change that Level3 Shift to the normal Alt but only found solution to do the opposite.