* @parent_menu_shell: (allow-none): the menu shell containing the triggering menu item, or %NULL
* @parent_menu_item: (allow-none): the menu item whose activation triggered the popup, or %NULL
* @func: (allow-none): a user supplied function used to position the menu, or %NULL
- * @data: user supplied data to be passed to @func.
+ * @data: (allow-none): user supplied data to be passed to @func.
* @button: the mouse button which was pressed to initiate the event.
* @activate_time: the time at which the activation event occurred.
*