treeview: Make row area multipress gesture react to all buttons
treeview: Make row area multipress gesture react to all buttons

The code is actually prepared for that, the gesture was initially limited
to only handling GDK_BUTTON_PRIMARY because it only used to handle row
activation.

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