>>>>> In <b4m8xe2t0uo.fsf@jpl.org> Katsumi Yamaoka wrote:

> Anyway, I'll make an effort to implement SWITCH-FUNCTION and
> CONTINUE arguments in Gnus.

Done.  I have not committed it yet, though.  The patch to the
v5-10 branch is attached.  It can also be applied to the Gnus
trunk with a slight hand work.

Now `gnus-user-agent' and `message-user-agent' regard CONTINUE
and SWITCH-FUNCTION arguments.  For instance, whenever you eval
the following form, you will be brought to the message buffer
named "*mail to whom*":

(let ((mail-user-agent 'gnus-user-agent))
  (compose-mail "whom" nil nil t 'pop-to-buffer))

If `message-mail-user-agent' is set to a certain agent, Message
passes SWITCH-FUNCTION and CONTINUE arguments to that agent.
For example, this lets Gnus use `sendmail-user-agent' to compose
a mail:

(let ((mail-user-agent 'gnus-user-agent)
      (message-mail-user-agent 'sendmail-user-agent))
  (compose-mail "whom" nil nil t 'pop-to-buffer))

Furthermore, I slightly changed the meaning of the nil value of
`message-generate-new-buffers' and made the value t the same as
the value `unique'.  While the nil value made a buffer with a
name such as "*mail message*" formerly, it now uses a name as
what the value `unique' uses, like "*mail to whom*".
The difference between nil and `unique' is that nil uses an
existing message buffer if any but `unique' always uses a new
message buffer.  This fits the name of the variable, doesn't it?
Note that nil distinguishes the buffer "*mail to whom*" from the
buffer "*mail*".  In other words, the value nil never uses the
existing buffer named "*mail*" when it is made to use the buffer
named "*mail to whom*".  The new value `standard' is similar to
nil but is for those who like simpler "*mail message*" names.

If there's no comment, I will install those changes.

In addition, I've also revised message-multiple-frames.el so as
to agree those changes.  It is avalable at:
ftp://ftp.jpl.org/pub/elisp/ or http://www.jpl.org/ftp/pub/elisp/

Regards,