TreeNodeElement neFirstVisible = this.radTreeView1.TreeViewElement.ViewElement.Children[0] as TreeNodeElement;
            RadMessageBox.Show("TopNode = " + neFirstVisible.Data.Text);

    DataTable table = new DataTable();
    table.Columns.Add("ParentId", typeof(int));
    table.Columns.Add("ChildId", typeof(int));
    table.Columns.Add("ProductId", typeof(int));
    table.Columns.Add("ProductCode", typeof(string));

    table.Rows.Add(0, 1, 3, "Pr - 01");
    table.Rows.Add(1, 2, 4, "P r- 02");
    table.Rows.Add(1, 3, 5, "Pr - 03");

    this.radTreeView1.DisplayMember = "ProductCode";
    this.radTreeView1.ParentMember = "ParentId"; 
    this.radTreeView1.ChildMember = "ChildId"; 
    this.radTreeView1.ValueMember = "ProductId";
    this.radTreeView1.DataSource = table;

    Private Sub RadForm1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Me.SongsTableAdapter.Fill(Me.MusicCollectionDataSet.Songs)
        Me.ArtistsTableAdapter.Fill(Me.MusicCollectionDataSet.Artists)
        Me.AlbumsTableAdapter.Fill(Me.MusicCollectionDataSet.Albums)

        AddHandler Me.RadTreeView1.NodeDataBound, AddressOf RadTreeView1_NodeDataBound

        Me.RadTreeView1.DataSource = Me.ArtistsBindingSource
        Me.RadTreeView1.DisplayMember = "ArtistName"
        Me.RadTreeView1.ValueMember = "ArtistID"
        Me.RadTreeView1.RelationBindings.Add(New RelationBinding(Me.AlbumsBindingSource, "AlbumName", "ArtistID", "ArtistID", "AlbumID"))
        Me.RadTreeView1.RelationBindings.Add(New RelationBinding(Me.SongsBindingSource, "SongName", "AlbumID", "AlbumID", "SongID"))
        Me.RadTreeView1.CheckBoxes = True
        Me.RadTreeView1.AutoCheckChildNodes = True
        Me.RadTreeView1.TriStateMode = True
        Me.RadTreeView1.ExpandAll()
    End Sub

    Private Sub RadTreeView1_NodeDataBound(sender As Object, e As RadTreeViewEventArgs)
        If e.Node.Level = 0 Then
            e.Node.CheckType = CheckType.None
        Else
            e.Node.CheckType = CheckType.CheckBox
        End If
    End Sub

    Private Sub RadTreeView1_NodeFormatting(sender As Object, e As TreeNodeFormattingEventArgs)
        If e.Node.Level = 0 Then
            e.NodeElement.ToggleElement.Visibility = Telerik.WinControls.ElementVisibility.Collapsed
        Else
            e.NodeElement.ToggleElement.Visibility = Telerik.WinControls.ElementVisibility.Visible
        End If
    End Sub

var xml = "<TreeView xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" MultiSelect=\"true\" AllowDragDrop=\"true\" LabelEdit=\"true\" AllowDrop=\"true\">  <Nodes Text=\"New Package\" Expanded=\"true\" ImageKey=\"Package\" Font=\"Microsoft Sans Serif; 8,25pt; style=Bold\">    <Tag xsi:type=\"xsd:string\">&lt;Info&gt;&lt;FullName&gt;\\New Package&lt;/FullName&gt;&lt;ObjectType&gt;Package&lt;/ObjectType&gt;&lt;IsRunnable&gt;False&lt;/IsRunnable&gt;&lt;IsContainer&gt;true&lt;/IsContainer&gt;&lt;/Info&gt;</Tag>    <Nodes Text=\"Query Engine\" ImageKey=\"QueryEngine\" Expanded=\"true\" Font=\"Microsoft Sans Serif; 8,25pt; style=Bold\">      <Tag xsi:type=\"xsd:string\">&lt;Info&gt;&lt;FullName&gt;\\Query Engine&lt;/FullName&gt;&lt;ObjectType&gt;QueryEngine&lt;/ObjectType&gt;&lt;IsRunnable&gt;true&lt;/IsRunnable&gt;&lt;IsTableEntity&gt;true&lt;/IsTableEntity&gt;&lt;IsCut&gt;false&lt;/IsCut&gt;&lt;/Info&gt;</Tag>    </Nodes>    <Nodes Text=\"Connector\" ImageKey=\"Irion.SQLServer\">      <Tag xsi:type=\"xsd:string\">&lt;Info&gt;&lt;FullName&gt;\\Connector&lt;/FullName&gt;&lt;ObjectType&gt;DBConnection&lt;/ObjectType&gt;&lt;IsCut&gt;false&lt;/IsCut&gt;&lt;/Info&gt;</Tag>    </Nodes>    <Nodes Text=\"Connector Link\" ImageKey=\"DatabaseDatalink\">      <Tag xsi:type=\"xsd:string\">&lt;Info&gt;&lt;FullName&gt;\\Connector Link&lt;/FullName&gt;&lt;ObjectType&gt;DatabaseDatalink&lt;/ObjectType&gt;&lt;IsRunnable&gt;true&lt;/IsRunnable&gt;&lt;IsTableEntity&gt;true&lt;/IsTableEntity&gt;&lt;IsCut&gt;false&lt;/IsCut&gt;&lt;/Info&gt;</Tag>    </Nodes>  </Nodes></TreeView>";

         public RadForm1()
        {
            InitializeComponent(); 

            this.radTextBox1.TextChanged += this.RadTextBox1_TextChanged;
             this.radTextBox2.TextChanged += this.RadTextBox2_TextChanged;
            List<Data> list = new List<Data>();
            this.radTreeView1.BeginUpdate();
            for (int i = 0; i < 100000; i++)
            {
                list.Add(new Data()
                {
                    Id = i,
                    Name = "MyData_"+i,
                    ParentId = -1
                }) ;

                this.radTreeView1.Nodes.Add("MyData_"+i);
            }
            this.radTreeView1.EndUpdate();
            this.radTreeView2.DisplayMember = "Name";
            this.radTreeView2.ParentMember = "ParentId";
            this.radTreeView2.DataSource = list; 
        }

         private void RadTextBox2_TextChanged(object sender, EventArgs e)
         {
               this.radTreeView2.Filter = this.radTextBox2.Text;
         } 
        private void RadTextBox1_TextChanged(object sender, EventArgs e)
        {
            this.radTreeView1.Filter = this.radTextBox1.Text;
        }
    }

    public class Data
    {
        public int Id { get; set; }
        public string Name { get; set; } 
        public int ParentId { get; set; }
    }