void Instance_SearchComplete(object sender, SearchEventArgs e)
        {
            treeView1.Nodes.Clear();
            XmlDocument doc = e.Result;

            treeView1.BeginUpdate();
            XmlNodeList list = doc.SelectNodes("//found");
            foreach (XmlNode node in list)
            {
                string text = node.SelectSingleNode("title/text()").Value;
                string url = node.SelectSingleNode("url/text()").Value;

                SearchResultNode result = new SearchResultNode(text, url);

                treeView1.Nodes.Add(result);

                XmlNodeList categories = node.SelectNodes("incategory/text()");
                foreach ( XmlNode category in categories )
                {
                    string catName = Controller.Instance.GetCategorieName( Int32.Parse(category.Value ) );
                    CategoryNode tnode = new CategoryNode(catName);
                    result.Nodes.Add(tnode);
                }
            }
            treeView1.EndUpdate();
        }