Transparent Window

Here is an example of how it could be done:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.border.*;
import java.awt.image.BufferedImage;

/**
* A demonstration of JFrame/JWindow transparency.
* Creates a draggable, transparent window.
*<p>
* Note: This demo assumes that the background image is static,
* which would not be true in the general case.
*
* @author R. Kevin Cole <cole@NoSpam.cfl.rr.com>
* 03/01/03
*/
//public class TransparentWindow extends JFrame
public class TransparentWindow extends JWindow
{
Dimension preferredSize = new Dimension(320,200);
public Dimension getMinimumSize() { return this.preferredSize; }
public Dimension getPreferredSize() { return this.preferredSize; }
protected int XDiff = 0;
protected int YDiff = 0;
protected static int xpos = 0;
protected static int ypos = 0;
protected static Robot    robot;

Image myImage;

public TransparentWindow() throws Exception
{
  super();

  ((JPanel) getContentPane()).setOpaque(false);
  setSize( getPreferredSize() );
  setBackground( Color.black );

  JPanel panel = (JPanel) getContentPane();
  panel.setBorder( new LineBorder( Color.white ) );
   
  // turn off double-buffering to reduce flicker in this demo
  // -not a good idea in the general case-
  RepaintManager.currentManager(null).setDoubleBufferingEnabled(false);

  addMouseMotionListener(new MyMouseMotionListener());
  robot = new Robot();

  Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
  Rectangle rec = new Rectangle();
  rec.setSize( screenSize );
  myImage = robot.createScreenCapture(rec);
}


public void paint( Graphics g )
{
  super.paint(g);

  if( myImage != null )
  {
  Dimension size = getSize();

  g.drawImage( myImage, 1, 1, size.width-2, size.height-2
      , xpos,ypos, xpos+size.width, ypos+size.height
      , null);
  }
}


public class MyMouseMotionListener extends MouseMotionAdapter
{
  public void mousePressed(MouseEvent evt)
  {
  XDiff = evt.getX() - xpos;
  YDiff = evt.getY() - ypos;
  if( XDiff < 0 ) XDiff = -XDiff;
  if( YDiff < 0 ) YDiff = -YDiff;
  }

  public void mouseDragged(MouseEvent e)
  {
  try
  {
    TransparentWindow.this.setLocation( xpos + (e.getX() - XDiff),
    ypos + (e.getY() - YDiff) );

    xpos = xpos + (e.getX() - XDiff);
    ypos = ypos + (e.getY() - YDiff);

    // force a repaint.
    TransparentWindow.this.invalidate();
    TransparentWindow.this.validate();
    TransparentWindow.this.repaint();
  } catch (Exception ex) { ex.printStackTrace(); }
  }
}

public static void main(String[] argv)  throws Exception
{
  TransparentWindow frame = new TransparentWindow();

  //Center the window
  Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
  Dimension frameSize = frame.getSize();
  xpos = (screenSize.width - frameSize.width)/2;
  ypos = (screenSize.height - frameSize.height)/2;

  frame.setLocation(xpos,ypos);
  frame.setVisible(true);
    }
}

Link: http://groups.google.dk/groups?q=java+transparent+jframe&hl=da&lr=&ie=UTF-8&oe=UTF-8&selm=qo506v4bqd5csd1qg92i3bkdb6v325cth9%404ax.com&rnum=5

CTRL-C CTRL-V!

Thanks mate!