code: def tabbar_toggled(self, settings, key, user_data):
          
          if settings.get_boolean(key):
              for n in self.guake.notebook_manager.iter_notebooks():
                  n.set_property("show-tabs", True)
          else:
              for n in self.guake.notebook_manager.iter_notebooks():
                  n.set_property("show-tabs", False)
docs: If the gconf var use_tabbar be changed, this method will be
          called and will show/hide the tabbar.