mo-paging.el

(defun mo-paging--what-page ()
  "Print page and line number of point."
  (interactive)
  (save-restriction
    (widen)
    (save-excursion
      (let ((count 1)
            (opoint (point)))
        (goto-char (point-min))
        (while (re-search-forward page-delimiter opoint t)
          (if (= (match-beginning 0) (match-end 0))
              (forward-char 1))
          (setq count (1+ count)))
        count))))

(defun mo-paging--forward-page ()
  (interactive)
  (widen)
  (forward-page)
  (narrow-to-page))

(defun mo-paging--backwards-page ()
  (interactive)
  (widen)
  (let ((p (mo-paging--what-page)))
    (backward-page)
    (when (= (mo-paging--what-page) p)
      (backward-page)))
  (narrow-to-page))

(defun mo-paging--goto-page (n)
  (interactive "nPage Number: ")
  (widen)
  (goto-char 0)
  (dotimes (x (- n 1) ())
    (forward-page))
  (narrow-to-page))


(define-minor-mode mo-paging-mode
  "narrow to pages and let you leaf through them by the usual keys
C-x [ - (backwards-page)
and
C-x ] - (forwards-page)"

  :lighter (:eval (format " [%s]" (mo-paging--what-page)))

  :after-hook (if mo-paging-mode
                  (progn
                    (setf header-line-format
                          "Forward: C-x ]  |  Backward: C-x [  |  Goto: C-x g")
                    (goto-char 0)
                    (narrow-to-page))

                (setf header-line-format nil)
                (widen))

  :keymap (list (cons (kbd "C-x ]") 'mo-paging--forward-page)
                (cons (kbd "C-x [") 'mo-paging--backwards-page)
                (cons (kbd "C-x g") 'mo-paging--goto-page)))