code: def keystroke_toggled(self, settings, key, user_data):
          
          for i in self.guake.notebook_manager.iter_terminals():
              i.set_scroll_on_keystroke(settings.get_boolean(key))
docs: If the gconf var scroll_keystroke be changed, this method
          will be called and will set the scroll_on_keystroke in all
          terminals open.