Test headerbar app menu fallback
Test headerbar app menu fallback

Make the sunny example useful by giving it a header bar
with app menu fallback. To test this under gnome-shell,
set APP_MENU_FALLBACK=1 in the environment.

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