(disabled-command-hook): Use `defvar' and add documentation string.

(disabled-command-hook): New option ! turns off disabled commands.

lisp/novice.el

@@ -36,7 +36,9 @@
 ;; and the keys are returned by (this-command-keys).
 
 ;;;###autoload
-(setq disabled-command-hook 'disabled-command-hook)
+(defvar disabled-command-hook 'disabled-command-hook
+  "Function to call to handle disabled commands.
+If nil, the feature is disabled, i.e., all commands work normally.")
 
 ;;;###autoload
 (defun disabled-command-hook (&rest ignore)
@@ -73,19 +75,21 @@
 	   (goto-char (point-max))))
        (princ "\n\n")
        (princ "You can now type
-Space to try the command just this once,
-      but leave it disabled,
+Space to try the command just this once, but leave it disabled,
 Y to try it and enable it (no questions if you use it again),
+! to try it and enable all commands in this session, or
 N to do nothing (command remains disabled).")
        (save-excursion
 	(set-buffer standard-output)
 	(help-mode)))
-     (message "Type y, n or Space: ")
+     (message "Type y, n, ! or Space: ")
      (let ((cursor-in-echo-area t))
        (while (not (memq (setq char (downcase (read-char)))
-			 '(?  ?y ?n)))
+			 '(?! ?  ?y ?n)))
 	 (ding)
-	 (message "Please type y, n or Space: "))))
+	 (message "Please type y, n, ! or Space: "))))
+    (if (= char ?!)
+	(setq disabled-command-hook nil))
     (if (= char ?y)
 	(if (and user-init-file
 		 (not (string= "" user-init-file))