🚀 go-pugleaf

Doing mh-yank-cur-msg in an MH draft buffer when no mark has been set
in the corresponding show-+foo buffer results in a "There is no region
now" error.  The problem is that we have

  mark-active == t  AND  (marker-position (mark-marker)) == nil

simultaneously in the show-+foo buffer.  

Either
(1) this should be prohibited (which may be a lost cause, given the number 
    of places that mark-active gets set without a corresponding check of
    the current mark, though you could
      (defun activate-mark (position &optional buffer) ...)
    to go along with the currently present deactivate-mark
    and tell people to use it), OR

(2) various pieces of code that check mark-active and then blithely go
    ahead and do (region-beginning) should be doing a bit more work
    (and the documentation for mark-active should be pointing out that
    having mark-active set doesn't guarantee non-nilness of the mark...)

If (2), then here's the fix for mh-yank-cur-msg :

*** /usr/local/src/emacs-19/lisp/mh-comp.el	Mon Mar 14 22:16:26 1994
--- -	Wed Aug 24 14:23:33 1994
***************
*** 822,828 ****
              (delete-windows-on mh-show-buffer))
          (set-buffer mh-show-buffer)     ; Find displayed message
!         (let ((mh-ins-str (cond ((if (boundp 'mark-active)
!                                      mark-active        ;Emacs 19
!                                      (mark))            ;Emacs 18
                                   (buffer-substring (region-beginning)
                                                     (region-end)))
--- 822,828 ----
              (delete-windows-on mh-show-buffer))
          (set-buffer mh-show-buffer)     ; Find displayed message
!         (let ((mh-ins-str (cond ((and (or (not (boundp 'mark-active)) 
!                                           mark-active)  ;Emacs 19
!                                       (marker-position (mark-marker)))
                                   (buffer-substring (region-beginning)
                                                     (region-end)))