/**
* Closes the diagnostic GUI if it previously has been opened. Otherwise
* this method does nothing.
*/
public void shutdownGUI() {
final UtilControl localGUI;
synchronized (this) {
localGUI = _localGUI;
_suspendShutdown.set(false);
_localGUI = null;
}
if (localGUI != null) {
localGUI.close();
}
}