void item_Changed(object sender, AXmlObjectEventArgs e)
 {
     AddToHashtable((AXmlAttribute)e.Object);
 }
        // Every item in the collection should be registered to these handlers
        // so that we can handle renames

        void item_Changing(object sender, AXmlObjectEventArgs e)
        {
            RemoveFromHashtable((AXmlAttribute)e.Object);
        }