Code to flip a window

I'm looking for a code to flip a window, like in the Tiger - Apple OS.
I though of the following algorithm but I can get it implemented right:

1. Capture the window who is about to be flipped.
2. Hide it and display the image.
This is the part which I don't know how to implement:
3. Start changing the image size so it looks like its being flipped.
4. Display a new window which is the "back side" of the original
window.

If anyone thinks that there is a better algorithm, or how to implement
the algorithm suggested, please...