mtm is the Micro Terminal Multiplexer, a terminal multiplexer.

It has four major features/princples:
 - Simplicity: there are three commands (change focus, split, close). There are
   no modes, no dozens of commands, no crazy feature list.
 - Compatibility: mtm emulates a classic ANSI text terminal. That means it
   should work out of the box on essentially all terminfo/termcap-based systems
   (even pretty old ones), without needing to install a new termcap entry.
 - Size mtm is small. The entire project is around 1000 lines of code.
 - Stability: mtm is "finished" as it is now. You don't need to worry about it
   changing on you unexpectedly. The only changes that can happen at this point
   are:
    - Bug fixes.
    - Translation improvements.
    - Accessibility improvements.
    - Fixes to keep it working on modern OSes.