final AttributeChangeNotification notif = (AttributeChangeNotification)o;
final StringBuffer b = super._stringify( notif );
append( b, "" );
final String attrName = notif.getAttributeName();
final String oldValue = SmartStringifier.toString( notif.getOldValue() );
final String newValue = SmartStringifier.toString( notif.getNewValue() );
final String msg = attrName + ": " + oldValue + " => " + newValue;
b.append( msg );
return( b.toString() );