It would be great to have an option in buttons to hide buttons from all players except the specified player who can interact with it as normal. It could simply be something like

createButton({click_function ="blah".....players={"White","Red"})

with it defaulting to "Gray" or nil or something for it to act like a normal button everyone can see and interact with.

This would be super useful for certain games, both for making secret choices, or maybe unique player specific displays on the table (Like having over player hands and such). I could also see it being used with inputs for players to be able to enter something and have it hidden from everyone else until some point in the game.