front.setLocation(X, Y);
Area mask = new Area(new Rectangle(0, 0, W, H));
mask.subtract(new Area(new Rectangle(W/4, H/4, W/2, H/2)));
WindowUtils.setWindowMask(front, mask);
front.addMouseListener(handler);
front.addMouseMotionListener(handler);
SwingUtilities.invokeAndWait(new Runnable() { public void run() {
back.pack();
back.setSize(new Dimension(W, H));