Ignoring all that babble bout patents and copyrights...

I see absolutly no reason why this couldn't be done in a rather simple (3rd-party) commodity.

1. Wait for hotbutton, basic Commodity-functionality
2. Scan Intuition for all Windows (scanning only for windows belonging to a certain app might be a bit tricky), trivial
3. Generate a layout that allows to show all windows while retaining maximal size, needs a bit of thinking
4. Open a borderless window in front of everything else (use the screens backdrop for good measure), again trivial
5. Blit and scale the windows into our previes win, not too hard
6. Wait for user input, we can do that ...
7. Check which window-image was clicked, it's getting easy
8 Close the preview win
9. Issue an WindowToFront() on that window.

If I wasn't so damn lazy