-ADD_ACKNOWLEDGER (Drum_notes_engraver, stem);
-ADD_ACKNOWLEDGER (Drum_notes_engraver, note_column);
+
+void
+Drum_notes_engraver::boot ()
+{
+ ADD_LISTENER (Drum_notes_engraver, note);
+ ADD_ACKNOWLEDGER (Drum_notes_engraver, stem);
+ ADD_ACKNOWLEDGER (Drum_notes_engraver, note_column);
+}