Immediate buy window of the market needs a button or a box that you can tick enabling one to buy the whole quantity of a selected item a seller is offering.
E.g. when someone is selling 3,511,775 units of mexallon and you wanna buy them all, then there should be an option to do that without having to type in that exact quantity. I know you can just type a single-digit number exceeding available quantity, but it would still be nice to have a ‘buy-all’ option.