check region action sensitivity from two more places that may alter it

gtk2_ardour/editor.cc

@@ -2346,6 +2346,7 @@ Editor::set_edit_point_preference (EditPoint ep, bool force)
 	}
 
 	reset_canvas_action_sensitivity (in_track_canvas);
+	sensitize_the_right_region_actions (false);
 
 	instant_save ();
 }

gtk2_ardour/editor_selection.cc

@@ -1002,6 +1002,8 @@ Editor::track_selection_changed ()
 
 	ActionManager::set_sensitive (ActionManager::track_selection_sensitive_actions, !selection->tracks.empty());
 
+	sensitize_the_right_region_actions (false);
+
 	/* notify control protocols */
 
 	ControlProtocol::StripableSelectionChanged (stripables);