ghetto writeroom in emacs

ghettowriteroom.el

(defvar-local writing-mode nil)
(defvar-local cached-mode-line nil)
(define-minor-mode writing-mode
  "Minor mode for writing"
  :variable writing-mode
  :init-value nil
  :group 'editing-basics
  (if (not writing-mode)
      (progn
	(toggle-frame-fullscreen)
	(fringe-mode nil)
	(set-window-margins nil 0 0)
	(setq mode-line-format cached-mode-line cached-mode-line nil))
    (progn
      (toggle-frame-fullscreen)
      (fringe-mode 0)
      (defconst x (/ (- (frame-width) 80) 2))
      (set-window-margins nil x x)
      (setq cached-mode-line mode-line-format mode-line-format nil))))