GtkWindow: Reset gestures after triggering right click titlebar action

Just like it happens for window dragging, we're likely to not see the
matching button release for this event, so we must reset the controller
manually here.

https://bugzilla.gnome.org/show_bug.cgi?id=758661

gtk/gtkwindow.c

@@ -1451,6 +1451,9 @@ multipress_gesture_pressed_cb (GtkGestureMultiPress *gesture,
       if (gtk_window_titlebar_action (window, event, button, n_press))
         gtk_gesture_set_sequence_state (GTK_GESTURE (gesture),
                                         sequence, GTK_EVENT_SEQUENCE_CLAIMED);
+
+      gtk_event_controller_reset (GTK_EVENT_CONTROLLER (gesture));
+      gtk_event_controller_reset (GTK_EVENT_CONTROLLER (priv->drag_gesture));
       return;
     }
   else if (button == GDK_BUTTON_MIDDLE && region == GTK_WINDOW_REGION_TITLE)