- Real sl = me->get_layout ()->get_dimension (ly_symbol2scm ("linethickness"));
- Link_array<Grob> heads (extract_grob_array (me, ly_symbol2scm ("heads")));
+ common = common->common_refpoint (me->get_system (), X_AXIS);
+
+ Real sl = me->layout ()->get_dimension (ly_symbol2scm ("line-thickness"));
+
+ extract_grob_set (me, "heads", heads);