Tmux is a terminal multiplexer coming from the BSD world : it enables a number of terminals (or windows), each running a separate program, to be created, accessed, and controlled from a single screen. tmux may be detached from a screen and continue running in the background, then later reattached. It uses the ncurses lib.
# pacman -S tmux
Configuration files can be found in /usr/share/tmux/. By default, the escape keys are C-b (where C- is the control key)
In order to have an «I want it to behave like screen» configuration, issue this command:
$ cp /usr/share/tmux/screen-keys.conf ~/.tmux.conf
For a system wide configuration, place tmux.conf in /etc/. More info can be found in the man page of tmux
$ man tmux