if (Skyline_pair *s = unsmob<Skyline_pair> (me->get_property ("vertical-skylines")))
{
ret.add_stencil (Lookup::points_to_line_stencil (0.1, (*s)[UP].to_points (X_AXIS))
if (Skyline_pair *s = unsmob<Skyline_pair> (me->get_property ("vertical-skylines")))
{
ret.add_stencil (Lookup::points_to_line_stencil (0.1, (*s)[UP].to_points (X_AXIS))