[gtk+] docs: add missing flag

[William Jon McCann <mccann src gnome org>]

commit cc7b5d0a573a8331d0197b65fc4441f73bcea3e9
Author: William Jon McCann <william jon mccann gmail com>
Date:   Mon Jan 20 19:56:56 2014 -0500

    docs: add missing flag

 gtk/gtkmenuitem.h |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkmenuitem.h b/gtk/gtkmenuitem.h
index 70dbfd1..3fa4a9b 100644
--- a/gtk/gtkmenuitem.h
+++ b/gtk/gtkmenuitem.h
@@ -57,6 +57,9 @@ struct _GtkMenuItem
 /**
  * GtkMenuItemClass:
  * @parent_class: The parent class.
+ * @hide_on_activate: If %TRUE, then we should always
+ *    hide the menu when the %GtkMenuItem is activated. Otherwise,
+ *    it is up to the caller.
  * @activate: Signal emitted when the item is activated.
  * @activate_item: Signal emitted when the item is activated, but also
  *    if the menu item has a submenu.