/// <summary>
        /// Appends a new child comment node to the currently selected element.
        /// </summary>
        public void AppendChildComment(XmlComment comment)
        {
            XmlElementTreeNode selectedNode = SelectedElementNode;

            if (selectedNode != null)
            {
                XmlCommentTreeNode newNode = new XmlCommentTreeNode(comment);
                newNode.AddTo(selectedNode);
                selectedNode.Expand();
            }
        }
        /// <summary>
        /// Appends a new child text node to the currently selected element.
        /// </summary>
        public void AppendChildTextNode(XmlText textNode)
        {
            XmlElementTreeNode selectedNode = SelectedElementNode;

            if (selectedNode != null)
            {
                XmlTextTreeNode newNode = new XmlTextTreeNode(textNode);
                newNode.AddTo(selectedNode);
                selectedNode.Expand();
            }
        }