I am trying to use PSGML 1.3.1 with Emacs 21.3, and there is a
conflict between PSGML and sgml-mode.el, because they both define
sgml-mode. I can unload-feature the original sgml-mode and then load
psgml, but that only works interactively. For some reason it doesn't
work in .emacs, perhaps because the original sgml-mode has already
been loaded by then to handle some XML files opened by Emacs desktop.
Taking sgml-mode.el out of the Emacs directory works up to a point,
but gives an error, probably because the desktop tries to load it.
To make this work I would need to remove all mention of sgml-mode.el
from the Emacs lisp directory. This would be bad because I would have
to do it all again next time I upgrade.
Alternatively, I could rename everything in PSGML (to psgml-mode,
etc). auto-mode-alist associates .sgml and .xml with sgml-mode, but
putting new entries at the beginning will override that. The question
is whether any other packages call sgml-mode explicitly. Several of
the standard ones refer to it (flyspell, tildify, whitespace, and
others) but don't actually call it. Does anyone know of any packages
that do?