Bug#804945: some keyboard shortcuts do not work with an additional keyboard

[Sylvain BERTRAND]

Package: gnome
Version: 1:3.14+3

On a laptop, I have a french layout native keyboard, but I use a dvorak USB
connected external keyboard.

For instance, screen lock shortcut, Super+l, does not work on the additional
external keyboard but does work with the native keyboard.
(I use the keyboard layout switcher topbar applet)