VetoableChangeListener[] listeners = getVetoableChangeListeners();  PropertyChangeEvent evt = new PropertyChangeEvent(this, propertyName, oldValue, newValue);  for (int i = 0; i < listeners.length; i++) listeners[i].vetoableChange(evt);
  protected void fireVetoableChange(String propertyName, Object oldValue,                                    Object newValue)          throws PropertyVetoException	{		//       Support for reporting constrained property changes.	}