code: def switch_showfilter_icon(self, toggled):
          
          at = QtCore.Qt.DownArrow if toggled else QtCore.Qt.RightArrow
          self.showfilter_tb.setArrowType(at)
docs: Switch the icon on the showfilter_tb
  
          :param toggled: the state of the button
          :type toggled: :class:`bool`
          :returns: None
          :rtype: None
          :raises: None