Glass pane上にペイントしたダイアログのボタンの位置の取得方法

public class MyGlassPane extends JComponent
{
    private Point _mouseClickedPoint;
    private JDialog _dialogue;
    private BufferedImage _buffer;

//	.
//	.
//	.

    public void createDialog(String message)
    {
        // Set a dialogue to be displayed.
        JOptionPane pane = 
            new JOptionPane(message,JOptionPane.WARNING_MESSAGE,
                    JOptionPane.DEFAULT_OPTION,null,null,null);
        _dialogue = pane.createDialog(null, "Message!!!");
        
        Dimension size = _dialogue.getSize();
        
        _buffer = 
            new BufferedImage(
                    size.width, size.height,BufferedImage.TYPE_INT_ARGB);
        
        Graphics2D g2d = _buffer.createGraphics();
        g2d.setClip(0, 0, size.width, size.height);
        for (int i = 0; i < _dialogue.getComponentCount(); i++)
        {
            _dialogue.getComponent(i).paint(g2d);
        }        
        g2d.dispose();
        
        repaint();
    }

    protected void paintComponent(Graphics g)
    {
        if (_mouseClickedPoint != null)
        {
            g.setColor(Color.DARK_GRAY.brighter());
            
            Rectangle b = new Rectangle(_mouseClickedPoint.x,
                                        _mouseClickedPoint.y,
                                        _buffer.getWidth(),
                                        _buffer.getHeight());
            g.drawImage(_buffer, b.x, b.y, null);
            g.drawRect(b.x, b.y, b.width, b.height);            
        }
    }

//	.
//	.
//	.

}