--- a/lisp/ChangeLog	Fri Dec 28 13:03:15 2012 +0900
+++ b/lisp/ChangeLog	Fri Dec 28 17:23:25 2012 +0900
@@ -1,3 +1,7 @@
+2012-12-28  Byrel Mitchell  <byrel.mitchell@gmail.com>
+
+	* menubar.el (check-menu-syntax): Implement :active in submenu specs.
+
 2012-08-03  Stephen J. Turnbull  <stephen@xemacs.org>
 
 	* menubar-items.el (default-menubar): Reorganize.

--- a/lisp/menubar.el	Fri Dec 28 13:03:15 2012 +0900
+++ b/lisp/menubar.el	Fri Dec 28 17:23:25 2012 +0900
@@ -79,9 +79,9 @@
     (setq menu (cdr menu)))
   (let (menuitem item)
     (while (keywordp (setq item (car menu)))
-      (or (memq item '(:config :included :filter :accelerator))
+      (or (memq item '(:config :included :filter :accelerator :active))
 	  (signal 'error
-		  (list "menu keyword must be :config, :included, :accelerator or :filter"
+		  (list "menu keyword must be :config, :included, :accelerator, :active or :filter"
 			item)))
       (if (or (not (cdr menu))
 	      (vectorp (nth 1 menu))

--- a/man/ChangeLog	Fri Dec 28 13:03:15 2012 +0900
+++ b/man/ChangeLog	Fri Dec 28 17:23:25 2012 +0900
@@ -1,3 +1,8 @@
+2012-12-28  Byrel Mitchell  <byrel.mitchell@gmail.com>
+
+	* lispref/menus.texi (Menu Format):
+	Document use of :active in submenu specs.
+
 2012-12-28  Stephen J. Turnbull  <stephen@xemacs.org>
 
 	* internals/internals.texi (Mercurial Basics):

--- a/man/lispref/menus.texi	Fri Dec 28 13:03:15 2012 +0900
+++ b/man/lispref/menus.texi	Fri Dec 28 17:23:25 2012 +0900
@@ -39,7 +39,7 @@
 menu if @code{popup-menu-titles} is non-@code{nil}.
 
 Immediately following the first element there may optionally be up
-to four keyword-value pairs, as follows:
+to five keyword-value pairs, as follows:
 
 @table @code
 @item :included @var{form}
@@ -64,7 +64,13 @@
 @item :accelerator @var{key}
 A menu accelerator is a keystroke which can be pressed while the menu is
 visible which will immediately activate the item.  @var{key} must be a char
-or the symbol name of a key.  @xref{Menu Accelerators}.
+or the symbol name of a key. 
+
+@item :active @var{form}
+@var{form} will be evaluated when the submenu is about to be displayed,
+and the menu contents will be displayed only if the result is non-@code{nil}.
+If the submenu is inactive, it will display the word "Invalid", grayed-out.
+@xref{Menu Accelerators}.
 @end table
 
 The rest of the menu consists of elements as follows: