@dch #GNUScreen was the closest. In #tmux you couldn't drive separate panes / windows, whereas in #Screen there are `:acladd $USERNAME` to share a socket with another user and the default behaviour is that an active window is personal per user connected.

I used to use GNU Screen for pair programming, but #LiveShare is truly revolutionary. I think that it's less of a hardware proceedings and more so proceedings in practical implementations of conflict-free data structures.