treeview不能展开的问题

用javascript生成了一个树,生成代码如下,不能展开, 后来发现给根接点expanded赋值在添加第二个节点时已改变，

这是树不能展开的原因。在最后加上一句话，把根节点的expanded属性重新设置成true，树才能顺利展开。

跟踪代码发现是在tree.htc文件的generateItem(), 方法中值被修改了。

至于为什么要修改我就不知道了

<% ... @ Page language="c#" Codebehind="WebForm1.aspx.cs" AutoEventWireup="false" Inherits="WebApplication1.WebForm1"  %>
<% ... @ Register TagPrefix="iewc" Namespace="Microsoft.Web.UI.WebControls" Assembly="Microsoft.Web.UI.WebControls"  %>
<! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"  >
< HTML >
     < HEAD >
         < title > WebForm1 </ title >
         < meta  name ="GENERATOR"  Content ="Microsoft Visual Studio .NET 7.1" >
         < meta  name ="CODE_LANGUAGE"  Content ="C#" >
         < meta  name ="vs_defaultClientScript"  content ="JavaScript" >
         < meta  name ="vs_targetSchema"  content ="http://schemas.microsoft.com/intellisense/ie5" >
     </ HEAD >
     < body  MS_POSITIONING ="GridLayout" >
         < form  id ="Form1"  method ="post"  runat ="server" >
             < iewc:TreeView  id ="DeptTree"  style ="Z-INDEX: 101; LEFT: 128px; POSITION: absolute; TOP: 200px"
                runat ="server" ></ iewc:TreeView >
         </ form >
         < script  type ="text/javascript" > ...
        var dpTree = document.getElementById("DeptTree");
        window.document.body.onload = function()
        ...{
            initTree();
        }
        function initTree()
        ...{
            var root = newTreeNode("0", "中国");
            alert(root.getAttribute("expanded"));
            dpTree.add(root);
            alert(root.getAttribute("expanded"));
            var child1 = newTreeNode("1", "湖北");
            child1.setAttribute("expanded", "true");
            root.add(child1);
            var child2 = newTreeNode("2", "武汉");
            child1.add(child2);
            root.setAttribute("expanded", "true");
        }
        function newTreeNode(id, name)
        ...{
            var node  = dpTree.createTreeNode();
            node.setAttribute("id", id );
            node.setAttribute("text", name);
            node.setAttribute("expanded", "true")
            return node;
        }
         </ script >
     </ body >
</ HTML >

 c