Undo doesn't seem to work? I also got into a situation where I had a card that got stuck in the board and wouldn't go away (but still responded to "on mouse over"). Eventually, I was able to take that card and place it into the right place.
When you get only one card left on the top left pile and it's revealed, you still get a "turned down card" to it's left, but there is none. After taking that card and clicking this turned card, it's graphics revert to "full pile".
Also, the window doesn't seem to answer well to being resized.
But my biggest gripe is that this seems like the wrong tool for the job. You could probably get a lot more productive with, say, QT for this kind of game (and with a smaller binary).
Other than those issues, plays nice and it's entertaining. Nice victory screen! =)
