public MetalInternalFrameUI(JInternalFrame b) 
{
       
    super(b);
}

 protected MouseInputAdapter createBorderListener(JInternalFrame w) 
{
        return new BorderListener1();
}

Returns the MouseInputAdapter that will be installed on the TitlePane.

 protected JComponent createNorthPane(JInternalFrame w) 
{
      return new MetalInternalFrameTitlePane(w);
}

 public static ComponentUI createUI(JComponent c) 
{
      return new MetalInternalFrameUI( (JInternalFrame) c);
}

 protected  void installKeyboardActions() 
{
      super.installKeyboardActions();
      ActionMap map = SwingUtilities.getUIActionMap(frame);
      if (map != null) {
          // BasicInternalFrameUI creates an action with the same name, we override
          // it as Metal frames do not have system menus.
          map.remove("showSystemMenu");
      }
}

 protected  void installListeners() 
{
        super.installListeners();
        frame.addPropertyChangeListener(metalPropertyChangeListener);
}

 public  void installUI(JComponent c) 
{
    super.installUI(c);
    Object paletteProp = c.getClientProperty( IS_PALETTE );
    if ( paletteProp != null ) {
        setPalette( ((Boolean)paletteProp).booleanValue() );
    }
    Container content = frame.getContentPane();
    stripContentBorder(content);
    //c.setOpaque(false);
}

 public  void setPalette(boolean isPalette) 
{
    if (isPalette) {
        LookAndFeel.installBorder(frame, "InternalFrame.paletteBorder");
    } else {
        LookAndFeel.installBorder(frame, "InternalFrame.border");
    }
    ((MetalInternalFrameTitlePane)titlePane).setPalette(isPalette);
}

 protected  void uninstallComponents() 
{
        titlePane = null;
        super.uninstallComponents();
}

 protected  void uninstallKeyboardActions() 
{
      super.uninstallKeyboardActions();
}

 protected  void uninstallListeners() 
{
        frame.removePropertyChangeListener(metalPropertyChangeListener);
        super.uninstallListeners();
}

 public  void uninstallUI(JComponent c) 
{
      frame = (JInternalFrame)c;
      Container cont = ((JInternalFrame)(c)).getContentPane();
      if (cont instanceof JComponent) {
        JComponent content = (JComponent)cont;
        if ( content.getBorder() == handyEmptyBorder) {
          content.setBorder(null);
        }
      }
      super.uninstallUI(c);
}