*Org Src init.el

(setq-default scroll-up-aggressively 0.0)
(add-hook 'post-command-hook
  (defun recenter+ ()
    (unless (and (symbolp this-command) (get this-command 'scroll-command))
      (with-current-buffer (window-buffer)
        (recenter (- (1+ (save-excursion
                           (vertical-motion (floor (window-screen-lines) 2))))))))))
(define-key global-map [remap scroll-down-command]
  (defun move-to-top-line () (interactive) (move-to-window-line 1)))
(define-key global-map [remap scroll-up-command]
  (defun move-to-bottom-line () (interactive) (move-to-window-line -1)))