Random notes on trouble shooting:

- io:formats go to /tmp/edit.out, which is re-created from scratch each time.

- Sometimes colours go strange, particularly (for me) when running in a
  shell on a remote machine. When this happens to me in xterm, I retry in
  rxvt and it tends to work. However, on *my* computer the colours are ok :-)

  Presumably some extra initialisation of the SLang library is needed.