Highlight Selected Row in a List

Since the dawn of computer interfaces, like green screen text terminals, it’s been a built-in function for a line to be highlighted when the user picks from a list. Could we not get a couple extra options in the list blocks to make this happen?
I have seen several examples of how to accomplish this, using wildly different methods, but I’ve not yet quite sussed out how any of them work in detail. And I’d like not to make my block screens any bigger than some of them already are for this universal function.