[疑难问题]jstree拖动树+types完美整合问题

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %><%@ Register Assembly="CrystalDecisions.Web, Version=10.5.3700.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"
    Namespace="CrystalDecisions.Web" TagPrefix="CR" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>无标题页</title>    <script type="text/javascript" src="js/jquery.js"></script>    <script type="text/javascript" src="js/jquery.cookie.js"></script>    <script type="text/javascript" src="js/jquery.hotkeys.js"></script>    <script type="text/javascript" src="js/jquery.jstree.js"></script>    <link type="text/css" rel="stylesheet" href="css/!style.css" />
    <link type="text/css" rel="stylesheet" href="!style.css" />    <script type="text/javascript" src="css/!script.js"></script></head>
<body>
    <form id="form1" runat="server">    <div class="jstree-draggable" style="margin: 10px 0; clear: both; border: 5px solid navy;
        background: aqua; color: navy; height: 40px; line-height: 40px; text-align: center;
        font-size: 20px;">
        I have the jstree-draggable class</div>
    <div id="demo1" class="demo" style="float:left;">
        <ul>
            <li id="phtml_1" rel="root"><a href="#">Root node 1</a>
                <ul>
                    <li id="phtml_2"><a href="#">Child node 1</a> </li>
                    <li id="phtml_3"><a href="#">Child node 2</a> </li>
                </ul>
            </li>
            <li id="phtml_4" rel="root"><a href="#">Root node 2</a> </li>
        </ul>
    </div>
    <div class="jstree-drop" id="temp1" style="border: 1px solid green;float:left;width:75%;
         height: 100px; line-height: 40px; text-align: center;
        font-size: 20px;">
        test</div>
    <script type="text/javascript" class="source">
$(function () {
$("#demo1").jstree({ 
"dnd" : {
"drop_finish" : function () {

if()
{
}
var temp = "<div style='border:1px solid black;left:"  + window.event.screenX + "px;top:" + (window.event.screenY/2) + "px;position:absolute;'>dddddddd</div>";


$("#temp1").append(temp);

alert(window.event.screenX + "    " + window.event.screenY);
},
"drag_check" : function (data) {
if(data.r.attr("id") == "phtml_1") {
return false;
}
return { 
after : false, 
before : false, 
inside : true 
};
},
"drag_finish" : function () { 
alert("DRAG OK"); 
}
},
"types" : {
    "valid_children" : [ "root" ],  
    "types" : {
        "root" : {
            "icon" : {
                "image" : "http://static.jstree.com/v.1.0rc/_docs/_drive.png"  
                     },  
                    "valid_children" : [ "default" ],
                    "max_depth" : 2,                                    //打开子节点的深度
                    "hover_node" : false,  
                    draggable   : false,
                    "select_node" : function () {return false;}  
                 },  
                "default" : {  
                     "valid_children" : [ "default" ] ,
                    draggable   : false                     
                }  
             }  
        },   "plugins" : [ "themes", "html_data", "dnd", "ui", "types" ]
});
});
    </script>
    </form>
</body>
</html>
请问一下如何才能让拥有子节点的父节点不能拖动进去 class为:jstree-drop的DIV中 而子节点可以拖动进去。
跪求答案.