private class ExternalChangeListener implements PropertyChangeListener {
@Override
public void propertyChange(PropertyChangeEvent evt) {
assert TreeMapper.MODE_PROPERTY.equals(evt.getPropertyName());
TreeMapperMode mode = (TreeMapperMode) evt.getNewValue();
if (mode == TreeMapperMode.SIMPLE) {
simpleModeItem.setSelected(true);
} else {
fullModeItem.setSelected(true);
}