JWindowをマウスで移動

public void createSplashScreen(String path) {
  ImageIcon img = new ImageIcon(getClass().getResource(path));
  DragWindowListener dwl = new DragWindowListener();
  splashLabel = new JLabel(img);
  splashLabel.addMouseListener(dwl);
  splashLabel.addMouseMotionListener(dwl);
  splashScreen = new JWindow(getFrame());
  splashScreen.getContentPane().add(splashLabel);
  splashScreen.pack();
  splashScreen.setLocationRelativeTo(null);
}

class DragWindowListener extends MouseAdapter {
  private final Point startPt = new Point();
  private Window window;

  @Override public void mousePressed(MouseEvent me) {
    startPt.setLocation(me.getPoint());
  }

  @Override public void mouseDragged(MouseEvent me) {
    if (window == null) {
      window = SwingUtilities.windowForComponent(me.getComponent());
    }
    Point eventLocationOnScreen = me.getLocationOnScreen();
    window.setLocation(eventLocationOnScreen.x - startPt.x,
                       eventLocationOnScreen.y - startPt.y);
    // loc = window.getLocation(loc);
    // int x = loc.x - start.getX() + me.getX();
    // int y = loc.y - start.getY() + me.getY();
    // window.setLocation(x, y);
  }
}