I frequently use screen to manage various chat clients, what would be ideal is if one could set some kind of "size lock" in screen that would allow connecting screen sessions to connect to some sort of viewport instead of just locking to the lower right.

This viewport needs to not jump around based on screen refresh or cursor change, (maybe an option set somewhere, since this could be useful in some cases and not in others) since not all curses-like interfaces keep the terminal cursor where text is input. (I use "finch" which uses a virtual cursor for text input)