Java.swing ... WindowDestroyer() ?

Hi guys. I'm beginning to work on some simple Java GUI's and I have a textbook which has a demo program that's meant for me to copy into an IDE of my own. Now everything works up until the part

WindowDestroyer myListener =new WindowDestroyer();

It says "cannot find symbol : class WindowDestroyer" when I compile. So is my textbook defining an object of a non-existent class or am I just missing something?

Thanks for your help.

[491 byte] By [ApRiXa] at [2007-11-27 5:51:08]