focus-manager: don't move focus up/down/left/right when no widget has focus
focus-manager: don't move focus up/down/left/right when no widget has focus

If no widget has focus, there is no defined behaviour for
up/down/left/right focus movements.

pwithnall/mx,jonnylamb/mx,clutter-project/mx,clutter-project/mx,pwithnall/mx,clutter-project/mx,jonnylamb/mx,pwithnall/mx,clutter-project/mx,jonnylamb/mx,pwithnall/mx,jonnylamb/mx