As a corrolary to this question, which I've been thinking about since reading it, what would it take to get something like SIGWINFOCUS established as a standard signal along with SIGWINCH? Obviously, it would be a way for a terminal application to know when it gains or loses focus in an X environment. Who should one talk to, what kind of code should one write, and where should it go?
EDIT: To be clear, I'm asking who/where/what in the landscape of UNIX software is responsible for how interprocess signals get defined, and what the process might be for creating new ones. I hope that helps and welcome further feedback.