关于java拖动对话框的标题栏的问题，实现代码在哪里？

[bbigface]

window和frame都可以通过鼠标拖动标题栏，但是jdk1.3和1.4的实现有不同，我想找到源码看看，恳请高手指教！

[congliu]

import java.awt.*;
import java.awt.event.MouseEvent;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.event.MouseInputAdapter;

public class UndecoratedFrame extends JFrame
{
private static final int TITLE_HEIGHT = 20;

public UndecoratedFrame() throws HeadlessException
{
super();
setUndecorated(true);

MouseHandler ml = new MouseHandler();
addMouseListener(ml);
addMouseMotionListener(ml);
}

public UndecoratedFrame(String title) throws HeadlessException
{
super(title);
setUndecorated(true);

MouseHandler ml = new MouseHandler();
addMouseListener(ml);
addMouseMotionListener(ml);
}

public Insets getInsets()
{
return new Insets(TITLE_HEIGHT, 1, 1, 1);
}

public void paint(Graphics g)
{
super.paint(g);
g.setColor(new Color(0, 0, 128));
g.drawRect(0, 0, getWidth()-1, getHeight()-1);
g.fillRect(0, 0, getWidth(), TITLE_HEIGHT);

FontMetrics fm = g.getFontMetrics();
g.setColor(Color.white);
g.drawString(getTitle(), 2, (TITLE_HEIGHT - fm.getHeight()) / 2 + fm.getAscent());
}

private class MouseHandler extends MouseInputAdapter
{
private Point point;

public void mousePressed(MouseEvent e)
{
if (e.getY() <= TITLE_HEIGHT) {
this.point = e.getPoint();
}
}

public void mouseDragged(MouseEvent e)
{
if (point != null) {
setCursor(Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));

Point p = e.getPoint();
int dx = p.x - point.x;
int dy = p.y - point.y;

int x = getX();
int y = getY();
setLocation(x + dx, y + dy);
}
}

public void mouseReleased(MouseEvent e)
{
point = null;
setCursor(Cursor.getDefaultCursor());
}
}

public static void main(String[] args)
{
JFrame f = new UndecoratedFrame("Undecorated Frame");
f.getContentPane().add(new JLabel("Hello World!", JLabel.CENTER), BorderLayout.CENTER);
f.setSize(400, 400);
f.setLocationRelativeTo(null);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}

}