menubutton: don't dereference NULL GdkEvent
menubutton: don't dereference NULL GdkEvent

Since we explictly call popup_menu with NULL when it's
keyboard-activated, we need to be careful and not access event->device
without checking for event != NULL before.

chergert/gtk,ebassi/gtk,chergert/gtk,ebassi/gtk,davidgumberg/gtk,bratsche/gtk-,Lyude/gtk-,ebassi/gtk,Adamovskiy/gtk,jigpu/gtk,davidgumberg/gtk,bratsche/gtk-,Distrotech/gtk2,Lyude/gtk-,Lyude/gtk-,msteinert/gtk,alexlarsson/gtk,grubersjoe/adwaita,ahodesuka/gtk,Lyude/gtk-,jessevdk/gtk,msteinert/gtk,jadahl/gtk,Adamovskiy/gtk,chergert/gtk,jessevdk/gtk,bratsche/gtk-,jadahl/gtk,jadahl/gtk,alexlarsson/gtk,jigpu/gtk,davidt/gtk,Lyude/gtk-,Adamovskiy/gtk,jigpu/gtk,Distrotech/gtk2,jigpu/gtk,msteinert/gtk,grubersjoe/adwaita,Sidnioulz/SandboxGtk,jessevdk/gtk,Lyude/gtk-,grubersjoe/adwaita,davidgumberg/gtk,davidt/gtk,grubersjoe/adwaita,davidt/gtk,ebassi/gtk,jigpu/gtk,ahodesuka/gtk,ahodesuka/gtk,davidgumberg/gtk,Sidnioulz/SandboxGtk,Adamovskiy/gtk,Distrotech/gtk2,ahodesuka/gtk,davidgumberg/gtk,jigpu/gtk,davidgumberg/gtk,Adamovskiy/gtk,jessevdk/gtk,bratsche/gtk-,jessevdk/gtk,ebassi/gtk,ebassi/gtk,grubersjoe/adwaita,Adamovskiy/gtk,chergert/gtk,Lyude/gtk-,davidgumberg/gtk,chergert/gtk,Adamovskiy/gtk,msteinert/gtk,Distrotech/gtk2,Adamovskiy/gtk,chergert/gtk,davidt/gtk,msteinert/gtk,ahodesuka/gtk,alexlarsson/gtk,Sidnioulz/SandboxGtk,Sidnioulz/SandboxGtk,jadahl/gtk,alexlarsson/gtk,ahodesuka/gtk,grubersjoe/adwaita,chergert/gtk,davidt/gtk,Distrotech/gtk2,bratsche/gtk-,jadahl/gtk,bratsche/gtk-,Sidnioulz/SandboxGtk,jigpu/gtk,jadahl/gtk,msteinert/gtk,jigpu/gtk,Distrotech/gtk2,alexlarsson/gtk,Lyude/gtk-,alexlarsson/gtk,Sidnioulz/SandboxGtk,ahodesuka/gtk,jessevdk/gtk,alexlarsson/gtk,jessevdk/gtk,grubersjoe/adwaita,chergert/gtk,alexlarsson/gtk,ahodesuka/gtk,jadahl/gtk,grubersjoe/adwaita,davidgumberg/gtk,jadahl/gtk,davidt/gtk