Make any windows transparent

With this code you can set the transparency of any window, only by knowing its hwnd. This could be interesting to do some work on, imagine an app that remembers the z-order of all windows and makes them more and more transparent according to their z-order!!! Now, I'm not a that good coder so maybe someone picks up where I left. I think it could be cool, dont you? :) Oh, almost forgot, only Win 2K/XP...