protected ShapeTile offset_shape(Polyline p_polyline,int p_half_width,int p_no){
  return p_polyline.offset_shape(p_half_width,p_no);
}

protected ShapeTile offset_shape ( Polyline p_polyline , int p_half_width , int p_no ) { return p_polyline . offset_shape ( p_half_width , p_no ) ; }
used for creating the shapes of a polyline_trace for this tree . overwritten in derived classes .
