if (credentials == null) {
// prompt for username and password
JTextField uField = new JTextField(15);
uField.setText(username);
JPasswordField pField = new JPasswordField(15);
pField.addHierarchyListener(new HierarchyListener() {
public void hierarchyChanged(HierarchyEvent e) {
final Component c = e.getComponent();
if (c.isShowing() && (e.getChangeFlags() & HierarchyEvent.SHOWING_CHANGED) != 0) {
Window toplevel = SwingUtilities.getWindowAncestor(c);
toplevel.addWindowFocusListener(new WindowAdapter() {