public Vector handles() {
if (handles == null) {
handles = new Vector();
handles.addElement(new NullHandle(this, RelativeLocator.northWest()));
handles.addElement(new NullHandle(this, RelativeLocator.northEast()));
handles.addElement(new NullHandle(this, RelativeLocator.southEast()));
handles.addElement(new NullHandle(this, RelativeLocator.southWest()));
}
return (Vector) handles.clone();
}