emacs-lock enhancements

[Juanma Barranquero]

I'm interested in incorporating into Emacs some of the functionality
(not code) of Noah Friedman's protbuf.el, i.e., the ability to protect
a buffer against killing.

Currently, emacs-lock.el does something similar, though it has some problems:

 - It's not a proper minor-mode, so the locked status doesn't show in
the modeline.
 - It conflates two meanings of "locked": it protects against killing,
and it avoids Emacs exiting while a buffer is locked.
 - It deals with telnet and shell buffers as special cases, instead of
handling all buffers with live processes.

I'm planning on enhancing emacs-lock's functionality to make possible
separating the dont-kill and dont-exit-emacs flags (so a buffer can be
non-kill, but does not stop Emacs from exiting, for example).

What is the best interface for that: having two different minor modes
(let's say "emacs-lock-dont-kill-mode' and
`emacs-lock-dont-exit-mode'), or just one and somehow setting a flag
to indicate the desired level of protection, sort of like
overwrite-mode distinguishes between "normal" and "binary" modes?

    Juanma