I couldn’t put the whole thing I wanted to in the title.
Anway, in my mod, Zombies!!!, when I press ALT+(any key) in my event deck window, it ends up printing that in the chat line (where you type to chat with other players). For some reason, it doesn’t do that in any other window that I can see, not even in the Main Map. I also wouldn’t know how to recreate this, so I’d say the easiest way to see it for yourself would be to download my mod and try it out for yourself.
Edit: Scratch that, it seems to happen in other windows, but it seems to be random, except when it comes to using commands on the cards/pieces in the window. After using an ALT combo command that does something, it almost always makes that key appear in the chat entry line.