(scroll-all-mode): Make argument optional. Add to doc string.

diff --git a/lisp/scroll-all.el b/lisp/scroll-all.el
index 9092cfa75250d7e61ff4711165a321038c887dcd..734a83baceff439dd79dc51ca725e432ef3692c5 100644 (file)
--- a/lisp/scroll-all.el
+++ b/lisp/scroll-all.el
@@ -122,8 +122,11 @@ use either \\[customize] or the function `scroll-all-mode'."
  
 
 ;;;###autoload
-(defun scroll-all-mode (arg)
-  "Toggle Scroll-All minor mode."
+(defun scroll-all-mode (&optional arg)
+  "Toggle Scroll-All minor mode.
+With ARG, turn Scroll-All minor mode on if ARG is positive, off otherwise.
+When Scroll-All mode is on, scrolling commands entered in one window
+apply to all visible windows in the same frame."
   (interactive "P")
   (setq scroll-all-mode
         (if (null arg) (not scroll-all-mode)