- ambitus_->set_object ("note-heads", scm_list_2 (heads_[DOWN]->self_scm (),
- heads_[UP]->self_scm ()));
+
+ Pointer_group_interface::add_grob (ambitus_, ly_symbol2scm ("note-heads"), heads_[DOWN]);
+ Pointer_group_interface::add_grob (ambitus_, ly_symbol2scm ("note-heads"), heads_[UP]);
+ Axis_group_interface::add_element (group_, accidental_placement);