Fix keyboard activation of menu buttons
Fix keyboard activation of menu buttons

Keyboard activation relies on the menu not being visible,
so ensure that it isn't when the menu is attached.

Problem tracked down by Vincent Le Garrec,
https://bugzilla.gnome.org/show_bug.cgi?id=688738

msteinert/gtk,Adamovskiy/gtk,chergert/gtk,chergert/gtk,grubersjoe/adwaita,ebassi/gtk,ahodesuka/gtk,chergert/gtk,jadahl/gtk,jigpu/gtk,Sidnioulz/SandboxGtk,grubersjoe/adwaita,ahodesuka/gtk,grubersjoe/adwaita,davidgumberg/gtk,jadahl/gtk,grubersjoe/adwaita,jessevdk/gtk,Sidnioulz/SandboxGtk,jessevdk/gtk,grubersjoe/adwaita,jessevdk/gtk,Lyude/gtk-,jessevdk/gtk,jigpu/gtk,jadahl/gtk,Lyude/gtk-,grubersjoe/adwaita,jadahl/gtk,alexlarsson/gtk,alexlarsson/gtk,davidgumberg/gtk,ahodesuka/gtk,msteinert/gtk,Lyude/gtk-,jigpu/gtk,ebassi/gtk,alexlarsson/gtk,alexlarsson/gtk,alexlarsson/gtk,ebassi/gtk,msteinert/gtk,Lyude/gtk-,ahodesuka/gtk,ahodesuka/gtk,chergert/gtk,davidgumberg/gtk,jadahl/gtk,davidgumberg/gtk,alexlarsson/gtk,jessevdk/gtk,jadahl/gtk,Lyude/gtk-,Adamovskiy/gtk,chergert/gtk,jadahl/gtk,Sidnioulz/SandboxGtk,ahodesuka/gtk,jigpu/gtk,Lyude/gtk-,jigpu/gtk,jigpu/gtk,Sidnioulz/SandboxGtk,jessevdk/gtk,chergert/gtk,Adamovskiy/gtk,ebassi/gtk,ebassi/gtk,Lyude/gtk-,grubersjoe/adwaita,alexlarsson/gtk,davidgumberg/gtk,ahodesuka/gtk,Adamovskiy/gtk,Sidnioulz/SandboxGtk,jigpu/gtk,msteinert/gtk,Adamovskiy/gtk,Adamovskiy/gtk,chergert/gtk,Adamovskiy/gtk,msteinert/gtk,Adamovskiy/gtk,Lyude/gtk-,davidgumberg/gtk,msteinert/gtk,jadahl/gtk,jessevdk/gtk,chergert/gtk,jigpu/gtk,grubersjoe/adwaita,ahodesuka/gtk,davidgumberg/gtk,ebassi/gtk,alexlarsson/gtk,Sidnioulz/SandboxGtk,davidgumberg/gtk