buffer-offer-save, gnus and mh-e

[Luc Teirlinck]

I plan to make buffer-offer-save a permanent local.  This already has
Richard's approval.  It means that it will, as a matter of principle,
no longer be appropriate for major modes to set buffer-offer-save,
regardless of whether doing so produces any concrete user visible bugs.

Grepping shows that the only affected modes are mail-mode,
message-mode and mh-folder-mode, which set buffer-offer-save to t.

The solution for that is to set buffer-offer-save to t in
`compose-mail' and no longer set it in the individual mail modes.  I
checked that this works for mail-mode and message-mode.  I could not
check it for mh-folder-mode, but I guess that it must work, since it
works through `compose-mail'.

For mail-mode there is no problem.  For message-mode and
mh-folder-mode, I was wondering.  I know that the gnus directory is
automatically synched, but I do not know whether the version of gnus
included with CVS Emacs is also supposed to work with prior Emacs
versions or with XEmacs.  For mh-e, I have no idea whatsoever how it
is supposed to be handled.

If conditionals would be required, things might look somewhat strange,
because setting buffer-offer-save would still be harmless, even in
Emacs 22.  The only problem is that major modes are not supposed to
touch permanent locals.

Sincerely,

Luc.