title: how to create internal frame in netbeans platform?
body: <p>I created class NewProject extends JInternalFrame. Then I create New...Action named "NEW", localised in File menu. I put code <code>NewProject p = new NewProject(); p.setVisible(true);</code> to the ActionPerformed method of the action. </p>
  
  <p>But when I run the module and click "NEW" in file menu, nothing appears.
  Where can be problem?</p>
  
  <p><strong>EDIT:</strong>
  I partially solved it by code:</p>
  
  <pre><code>public void actionPerformed(ActionEvent e) {
  
      JInternalFrame f = new JInternalFrame();
      f.setSize(500, 500);
      f.setVisible(true);
      JDesktopPane p = new JDesktopPane();
      p.add(f);
  
     //WindowManager.getDefault().getMainWindow().setTitle("fFF");
     WindowManager.getDefault().getMainWindow().add(p)
  </code></pre>
  
  <p>}</p>
  
  <p>but GUI is broken. When I create new internal frame, the black background appears as I move by that frame.
  Any idea how to solve it?</p>