> What do you think about implementing the same behavior for
 > markers like it's implemented by 'comint-move-point-for-output'?
 > I.e. the same way as 'comint-move-point-for-output' moves point
 > to the end of the output, after erasing the buffer markers could
 > move their positions towards their previous valid position until
 > there is enough reverted text that they reach the old position.
 >
 > This is straightforward to implement.  I see print.c has a question
 > in the comments:
 >
 >      case PVEC_MARKER:
 >        print_c_string ("#<marker ", printcharfun);
 >        /* Do you think this is necessary?  */
 >        if (XMARKER (obj)->insertion_type != 0)
 > 	print_c_string ("(moves after insertion) ", printcharfun);
 >
 > I think this is necessary.  And this 'insertion_type' could also
 > move after insertion until it reaches its old position in the
 > reverted buffer.

'auto-revert-tail-mode' already has

       (when buffer-file-name
         (setq eob (eobp))
         (walk-windows
          (lambda (window)
            (and (eq (window-buffer window) buffer)
                 (= (window-point window) (point-max))
                 (push window eoblist)))
          'no-mini t))

plus

       (when buffer-file-name
         (when eob (goto-char (point-max)))
         (dolist (window eoblist)
           (set-window-point window (point-max)))))

without changing the markers' point insertion types.  We can easily
extend that to handle a window's previous buffers' points.  But
changing the insertion type of markers is far too delicate with all
the implications Eli cited.  We should avoid that wherever possible.

BTW, the last patch I sent was needlessly complicated - a window's
next buffers don't have any markers.  I attach a better one.

martin