Forty Thieves - Visible discard pile history
tl;dr - I would like to see the entire history of my discard pile laid across the screen, rather than only the top-most card.
As anyone who plays Forty Thieves will tell you, it is not always the correct play just because you have a play to make. Some times it is a benefit to pass up making a play. However, it is very important to know (or remember, if you have eidetic memory) what cards have already been discarded. This is true especially later in the game: do I drop the 3h into a free spot on the tableau or not? If you can look back at your discard history and see that there is no 2h in it, you probably might want to. Do I have another 4h coming that I can build down on? Being able to see your discard history would be a nice feature that will save me mashing my mouse button clicking the undo button 30-40 times.