public void addPropertyChangeListener(PropertyChangeListener listener){
  List<PropertyChangeListener> l=Arrays.asList(listenerList.getListeners(PropertyChangeListener.class));
  if (!l.contains(listener)) {
    listenerList.add(PropertyChangeListener.class,listener);
  }
}

public void addPropertyChangeListener ( PropertyChangeListener listener ) { List < PropertyChangeListener > l = Arrays . asList ( listenerList . getListeners ( PropertyChangeListener . class ) ) ; if ( ! l . contains ( listener ) ) { listenerList . add ( PropertyChangeListener . class , listener ) ; } }
add a listener for this pane ' s property change events
