add a stub function to the titlebar

terminatorlib/titlebar.py

@@ -21,6 +21,10 @@ class Titlebar(gtk.EventBox):
         """Connect the supplied function to clicking on the group icon"""
         pass
 
+    def update(self):
+        """Update our contents"""
+        pass
+
     def update_terminal_size(self, width, height):
         """Update the displayed terminal size"""
         pass