code: def set_active(self, ind):
          
          DEBUG_MSG("set_active()", 1, self)
          self._ind = ind
          if ind != None:
              self._active = [ self._axes[i] for i in self._ind ]
          else:
              self._active = []
          # Now update button text wit active axes
          self._menu.updateButtonText(ind)
docs: ind is a list of index numbers for the axes which are to be made active