def update_active(self):
        """Update the active marker on the marker Canvas"""
        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")
Update the active marker on the marker Canvas