Work around a GtkBuilder deficiency
Work around a GtkBuilder deficiency

It turns out that an <object> with just a <signal> in it does
not work right in GtkBuilder. Work around by adding a property.

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