(defun toggle-maximize-buffer () "Maximize buffer"
  (interactive)
  (if (= 1 (length (window-list)))
    (jump-to-register '_)
    (progn
      (set-register '_ (list (current-window-configuration)))
      (delete-other-windows))))

;; Bind it to a key.
;; (global-set-key [(super shift return)] 'toggle-maximize-buffer)