public interface IPartialRenderingCompositeControl
{
    void RenderUpdatePanel(CompositionUpdatePanel updatePanel, HtmlTextWriter writer);
}

public class CompositionUpdatePanel : UpdatePanel
{
    private IPartialRenderingCompositeControl _compositeControl;
    private ContentControl _content;
    public CompositionUpdatePanel(IPartialRenderingCompositeControl compositeControl)
    {
     _compositeControl = compositeControl;
     _content = new ContentControl();
     ContentTemplate = new Template(_content);
    }
    public Control Content
    {
     get
     {
        return _content;
     }
    }
    protected override void OnInit(EventArgs e)
    {
     base.OnInit(e);
     Controls.Clear();
     Controls.Add(_content);
    }
    private class Template : ITemplate
    {
     private ContentControl _ContentControl;
     public Template(ContentControl content)
     {
        _ContentControl = content;
     }
     public void InstantiateIn(Control container)
     {
        container.Controls.Add(_ContentControl);
     }
    }
    private class ContentControl : Control
    {
     protected override void Render(HtmlTextWriter writer)
     {
        CompositionUpdatePanel updatePanel = (CompositionUpdatePanel)Parent;
        if (updatePanel._compositeControl != null)
        {
         updatePanel._compositeControl.RenderUpdatePanel(updatePanel, writer);
        }
        else
        {
         base.RenderChildren(writer);
        }
     }
    }
}

[ToolboxData("<{0}:DepartmentTreeView runat=server></{0}:DepartmentTreeView>")]
public class DepartmentTreeView : CompositeControl, IPartialRenderingCompositeControl
{
    private CompositionUpdatePanel _Container;
    private TreeView _DepartmentTreeView;
    public event EventHandler DepartmentIDChanged;
    public Nullable<Guid> DepartmentID
    {
     get
     {
        return (Nullable<Guid>)this.ViewState["DepartmentID"];
     }
     set
     {
        if ((Nullable<Guid>)this.ViewState["DepartmentID"] != value)
        {
         this.ViewState["DepartmentID"] = value;
         if (value.HasValue)
         {
            AIO.Web.Utils.TreeViewUtils.TreeViewSelectValue(_DepartmentTreeView, value.Value.ToString());
            this.ViewState["DepartmentName"] = _DepartmentTreeView.SelectedNode.Text;
         }
         else
         {
            if (_DepartmentTreeView.SelectedNode != null)
            {
             _DepartmentTreeView.SelectedNode.Selected = false;
             this.ViewState["DepartmentName"] = String.Empty;
            }
         }
        }
     }
    }
    public string DepartmentName
    {
     get
     {
        return (string)this.ViewState["DepartmentName"];
     }
    }
    public void ClearSelected()
    {
     if(_DepartmentTreeView.SelectedNode != null)
     {
        _DepartmentTreeView.SelectedNode.Selected = false;
     }
    }
    protected void BuildTree()
    {
     _DepartmentTreeView.Nodes.Clear();
     _DepartmentTreeView.Nodes.Add(new TreeNode("Null"));
     DataSet ds = AIO.WIT.Data.DepartmentDataObject.ReadCore();
     int                               
     TreeNode[] Nodes = new TreeNode[Count + 1];
     Nullable<int>[] ParentSQNs = new Nullable<int>[Count + 1];
     foreach (DataRow dr in ds.Tables[0].Rows)
     {
        Nodes[((int)dr["DepartmentSQN"])] = new TreeNode((string)dr["DepartmentName"], ((Guid)dr["DepartmentID"]).ToString());
        if (dr["ParentSQN"].GetType() == typeof(DBNull))
        {
         ParentSQNs[(int)dr["DepartmentSQN"]] = null;
        }
        else
        {
         ParentSQNs[(int)dr["DepartmentSQN"]] = (int)dr["ParentSQN"];
        }
     }
     for (int i = 1; i < Count + 1; i++)
     {
        if (ParentSQNs[i].HasValue)
        {
         Nodes[ParentSQNs[i].Value].ChildNodes.Add(Nodes[i]);
        }
        else
        {
         _DepartmentTreeView.Nodes.Add(Nodes[i]);
        }
     }
    }
    protected override void OnInit(EventArgs e)
    {
     base.OnInit(e);
    }
    protected override void CreateChildControls()
    {
     _Container = new CompositionUpdatePanel(this);
     _Container.Mode = UpdatePanelMode.Conditional;
     _Container.RenderMode = UpdatePanelRenderMode.Inline;
     _Container.ID = "Container";
     Controls.Add(_Container); 
     _DepartmentTreeView = new TreeView();
     _DepartmentTreeView.ID = "DepartmentTreeView";
     BuildTree();
     _DepartmentTreeView.SelectedNodeChanged += delegate(object sender, EventArgs e)
     {
        if (_DepartmentTreeView.SelectedNode.Text == "Null")
        {
         this.ViewState["DepartmentID"] = null;
         this.ViewState["DepartmentName"] = String.Empty;
        }
        else
        {
         this.ViewState["DepartmentID"] = new Guid(_DepartmentTreeView.SelectedNode.Value);
         this.ViewState["DepartmentName"] = _DepartmentTreeView.SelectedNode.Text;
        }
        if (DepartmentIDChanged != null)
        {
         DepartmentIDChanged(this, new EventArgs());
        }
     };
     _Container.Content.Controls.Add(_DepartmentTreeView);
    }
    void IPartialRenderingCompositeControl.RenderUpdatePanel(CompositionUpdatePanel updatePanel, HtmlTextWriter writer)
    {
     _DepartmentTreeView.RenderControl(writer);
    }
}

[ToolboxData("<{0}:DepartmentSelect runat=server></{0}:DepartmentSelect>")]
public class DepartmentSelect : CompositeControl, IPartialRenderingCompositeControl
{
    private CompositionUpdatePanel _Container;
    private TextBox _DepartmentTextBox;
    private Panel _DepartmentTreeViewPanel;
    private DepartmentTreeView _DepartmentTreeView;
    private PopupControlExtender _PopupControlExtender;
    private PopupControlProperties _PopupControlProperties;
    public Nullable<Guid> DepartmentID
    {
     get
     {
        return _DepartmentTreeView.DepartmentID;
     }
     set
     {
        _DepartmentTreeView.DepartmentID = value;
     }
    }
    protected override void OnInit(EventArgs e)
    {
     base.OnInit(e);
    }
    protected override void CreateChildControls()
    {
     _Container = new CompositionUpdatePanel(this);
     _Container.Mode = UpdatePanelMode.Conditional;
     _Container.RenderMode = UpdatePanelRenderMode.Inline;
     _Container.ID = "Container";
     Controls.Add(_Container);
     _DepartmentTextBox = new TextBox();
     _DepartmentTextBox.ID = "DepartmentTextBox";
     _Container.Content.Controls.Add(_DepartmentTextBox);
     _DepartmentTreeViewPanel = new Panel();
     _DepartmentTreeViewPanel.ID = "DepartmentTreeViewPanel";
     _DepartmentTreeViewPanel.CssClass = "PopupControl";
     _DepartmentTreeView = new DepartmentTreeView();
     _DepartmentTreeView.ID = "DepartmentTreeView";
     _DepartmentTreeView.DepartmentIDChanged += delegate(object sender, EventArgs e)
     {
        _DepartmentTextBox.Text = _DepartmentTreeView.DepartmentName;
        _DepartmentTreeView.ClearSelected();
        _PopupControlExtender.Commit(_DepartmentTreeView.DepartmentName);
     };
     _DepartmentTreeViewPanel.Controls.Add(_DepartmentTreeView);
     _Container.Content.Controls.Add(_DepartmentTreeViewPanel);
     _PopupControlProperties = new PopupControlProperties();
     _PopupControlProperties.ID = "PopupControlProperties";
     _PopupControlProperties.TargetControlID = "DepartmentTextBox";
     _PopupControlProperties.PopupControlID = "DepartmentTreeViewPanel";
     _PopupControlProperties.Position = PopupControlPopupPosition.Bottom;
     _PopupControlExtender = new PopupControlExtender();
     _PopupControlExtender.ID = "PopupControlExtender";
     _PopupControlExtender.TargetProperties.Add(_PopupControlProperties);
     Controls.Add(_PopupControlExtender);
    }
    void IPartialRenderingCompositeControl.RenderUpdatePanel(CompositionUpdatePanel updatePanel, HtmlTextWriter writer)
    {
     _DepartmentTextBox.RenderControl(writer);
     _DepartmentTreeViewPanel.RenderControl(writer);
     _PopupControlExtender.RenderControl(writer);
    }
}

public class TreeViewUtils
{
    public static void TreeViewExpandToSelected(TreeView tv)
    {
     TreeNode tmp = tv.SelectedNode;
     if (tmp != null)
     {
        while (tmp.Parent != null)
        {
         tmp = tmp.Parent;
         tmp.Expand();
        }
     }
    }
    public static Boolean TreeViewSelectValue(TreeView tv, string value)
    {
     Boolean bResult = false;
     foreach (TreeNode tr in tv.Nodes)
     {
        if (TreeViewSelectValue(tr, value))
        {
         bResult = true;
         break;
        }
     }
     if (bResult)
     {
        TreeViewExpandToSelected(tv);
     }
     else
     {
        if (tv.SelectedNode != null)
        {
         tv.SelectedNode.Selected = false;
        }
     }
     return bResult;
    }
    protected static Boolean TreeViewSelectValue(TreeNode tr, string value)
    {
     if (tr.Value == value)
     {
        tr.Selected = true;
        return true;
     }
     foreach (TreeNode test in tr.ChildNodes)
     {
        if (TreeViewSelectValue(test, value))
        {
         return true;
        }
     }
     return false;
    }
}

[DataObject(true)]
public class DepartmentDataObject
{
    [DataObjectMethod(DataObjectMethodType.Select, true)]
    public static DataSet ReadCore()
    {
     Database db = DatabaseFactory.CreateDatabase("WorkItemTrack");
     string sqlCommand = "Department_SelectCore";
     DbCommand dbCommand = db.GetStoredProcCommand(sqlCommand);
     db.AddReturnValueParameter(dbCommand);
     return db.ExecuteDataSet(dbCommand);
    }
}

ALTER PROCEDURE dbo.Department_SelectCore     
AS
    SET NOCOUNT ON 
SELECT 
Department.DepartmentID, 
Department.DepartmentSQN, 
Department.DepartmentName, 
Department.ParentID, 
Parent.DepartmentSQN AS ParentSQN
FROM Department 
LEFT OUTER JOIN Department AS Parent ON Parent.DepartmentID = Department.ParentID
ORDER BY Department.DepartmentSQN
    RETURN

DepartmentID uniqueidentifier, 
DepartmentSQN int, 
DepartmentName nvarchar(32), 
ParentID uniqueidentifier