> I have no idea about the complexity about adding this feature; there's
> already a mini-buffer window which behaves in some aspects like a status
> bar (split-independant width, fixed position, no mode line), so I
> believe it would be possible to add a status bar just under (or above)
> the minibuffer without modifying a ton of code.
>
> Would someone know if it's possible to do it in emacs lisp, without
> modifying the C code ? It would make developement much easier.

With current trunk you can try (experimentally)

(display-buffer
  (get-buffer-create "foo")
  '((use-side-window bottom 0) (pop-up-window-set-height . 1)))

How you update the contents of foo is obviously entirely left to you.

martin