(blink-matching-paren-distance): Document the meaning of nil value,

and allow to customize to nil.

diff --git a/lisp/simple.el b/lisp/simple.el
index cf291ca44ff0c9c5d5e48755f68b96673f7217dd..a0eeaa2d00fc7ea393bc1b9ba29c687dfddbe765 100644 (file)
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -4207,8 +4207,9 @@ when it is off screen)."
   :group 'paren-blinking)
 
 (defcustom blink-matching-paren-distance (* 25 1024)
-  "*If non-nil, is maximum distance to search for matching open-paren."
-  :type 'integer
+  "*If non-nil, maximum distance to search backwards for matching open-paren.
+If nil, search stops at the beginning of the accessible portion of the buffer."
+  :type '(choice (const nil) integer)
   :group 'paren-blinking)
 
 (defcustom blink-matching-delay 1