relax the comparison of subject lines

[Urs Thuermann <urs@isnogud.escape.de>]

I'd like to modify the comparison of subject lines, which determines
if the subject line in a summary buffer is the same as the previous
one (and therefore not repeatedly printed) or not.

AFAIK, the usual comparison considers two subject lines equal, if they
are exactly identical or if they only differ in that one of them has a
"Re: " prepended.

I am on one mailing list, where the mailing list server inserts a
space after the colon of the "subject:" header of each message posted.
This causes Gnus to consider the subjects to be different, as they
appear as

  "Subject:  foo"
  "Subject:  Re: foo"   or   "Subject:  Re:  foo"

i.e. it looks like a " Re:" or a " Re: " has been prepended.  I have
written to the list and asked this to be fixed, but don't know if and
when it will be done.

Micro$hit loves to disturb many mailing list users by using "AW: " for
the german word "Antwort" which means reply, instead of the "Re: "
which is described in some RFC (forgot the number, probably 2822).
Others use "RE: " instead of "Re: ".

I have seen some MUAs append a space to the subject line when replying
to a mail.

All these bugs should of course better be fixed in the broken MUAs and
mailing list servers, but since they mostly will not, it would be nice
if I could configure Gnus to consider all these subjects equal, i.e.
two subjects should be equal, if one of them has " *([Rr][Ee]|AW): *"
prepended and/or if it has " *" appended.

It would further be nice, if replying to a subject "AW: foo" would
cause Gnus to generate a subject "Re: foo" in the reply instead of
"Re: AW: foo".

Can this be done?


urs