public static void addPropertiesListListener(PropertiesListListener listener){
  if (!propertieslistListeners.contains(listener)) {
synchronized (propertieslistListeners) {
      propertieslistListeners.add(listener);
    }
  }
}

public static void addPropertiesListListener ( PropertiesListListener listener ) { if ( ! propertieslistListeners . contains ( listener ) ) { synchronized ( propertieslistListeners ) { propertieslistListeners . add ( listener ) ; } } }
add recent file listener
