It's not any one thing, but it's a lot of small things. When I last looked a couple of years ago, vertical split wasn't in screen mainline and so it was non-sta

It's not any one thing, but it's a lot of small things. When I last looked a couple of years ago, vertical split wasn't in screen mainline and so it was non-starter for me. Check out the list of tmux commands: it's a very powerful program that's continuously being enhanced. Dunno if screen has this, but in tmux IIRC, you can have two different tmux servers running in totally different processes, and transfer a window from one server to another. That's pretty cool, imho. The graphical equivalent would be running two VNC servers, and moving an xterm window from one to the other. Another cool thing: pipe the entire contents of a window in realtime to an arbitrary program.