列表框如何实现折叠多级显示？

Question

<div onclick="with(div1.style)display=(display==''?'none':'')">aa</div>
<div id=div1 style=display:none>
a1<br>
a2<br>
</div>
<div onclick="with(div2.style)display=(display==''?'none':'')">bb</div>
<div id=div2 style=display:none>
b1<br>
b2<br>
</div>

Answer 1

<object classid="clsid:C74190B6-8589-11D1-B16A-00C0F0283628" id="TreeView1" width="170" height="350">
<PARAM NAME="LineStyle" VALUE="1"> 
<PARAM NAME="Style" VALUE="7"> 
</object>
<script language=vbs>
TreeView1.Nodes.Add ,, "csdn","中国程序员大本营"
TreeView1.Nodes.Add ,, "csdn2","中国程序员大本营2"
TreeView1.Nodes.Add "csdn",4,"expert","专家在线"
TreeView1.Nodes.Add "csdn",4,"expert2","专家在线2"
TreeView1.Nodes.Add "expert",4,"asp","ASP版"
sub TreeView1_DblClick
select case TreeView1.SelectedItem.Text 
case "中国程序员大本营":url="http://www.csdn.net"
case "专家在线":url="http://www.csdn.net/expert"
case "ASP版":url="http://www.csdn.net/Expert/index_room.asp?room=23"
end select
window.open url,"_self"
end sub
</script>