def modify_state_for_body(s, body):
            s.layers['segmentation'].segments = frozenset([body.segment_id])
            s.voxel_coordinates = body.bbox_start + body.bbox_size // 2
def _update_width(self, width_diff):
    if self._items_total_width is None:
      self._items_total_width = self.get_allocation().width