code: def update_active(self):
          
          if self.active is not None:
              self.update_state(self.active, "normal")
          if self.current_iid == self.active:
              self._active = None
              return
          self._active = self.current_iid
          if self.active is not None:
              self.update_state(self.active, "active")
docs: Update the active marker on the marker Canvas