title: Why setExtendedState(JFrame.ICONIFIED)does not work while windows screen locked?
body: <p>all.
  i want to minimize my jframe with setExtendedState(JFrame.ICONIFIED), in most case, it works properly, but when it does not work when i lock my os(windows XP) screen with WIN+L.My wimple code are as follows:</p>
  
  <pre><code>import javax.swing.JDialog;
  import javax.swing.JFrame;
  
  public class FrameTest extends JFrame {
      public static FrameTest ft = new FrameTest();
  
      public static void main(String[] args)
      {
          FrameTest.ft.setVisible(true);
          FrameTest.ft.setLocation(300, 300);
          try {
              Thread.sleep(3000);
          } catch (InterruptedException e) {
              // TODO Auto-generated catch block
              e.printStackTrace();
          }
          JDialog dlg = new JDialog( ft, "xxx", true );
          ft.setExtendedState(JFrame.ICONIFIED);
          dlg.setVisible(true);//if not have this line, it works also in screen lock case 
      }   
  }
  </code></pre>
  
  <p>Any help will be appreciated.</p>