about callback for GtkItemfactory

[Wan Hing Wah <50191914 ee cityu edu hk>]

According to my computer book which teach gtk programming,
the callback for items in GtkItemFactory is
void handler (gpointer callback_data, guint callback_action,GtkWidget *widget)

however,the callback for "activate" signal for gtk_menu_item is
void handler(GtkWidget *widget,gpointer callback_data);

so,when i retrieve a menu item by item=gtk_item_factory_get_widget()
and then connect the call back by gtk_signal_connect(item,"activate",handler,data);
which function prototype of the handler should I use?