ExtJS TreePanel for Campaigns Visualforce Component

<apex:component controller="CampaignHierarchyController">
    <!-- a VF component for selecting a campaign from the hierarchy with an ExtJS TreePanel -->
    <!-- Jeff Trull 2010-09-19 -->
    <apex:attribute name="allowinactiveselect" type="Boolean" description="Whether to permit users to select inactive Campaigns" default="false"/>
    <apex:attribute name="fn" type="String" description="name of a Javascript function to call with ID once a Campaign is selected." required="true"/>

    <!-- load ExtJS -->
    <apex:stylesheet value="{!$Resource.ExtJS}/resources/css/ext-all.css" />
    <apex:includeScript value="{!$Resource.ExtJS}/adapter/ext/ext-base.js"/>
    <apex:includeScript value="{!$Resource.ExtJS}/ext-all.js"/>
    <script type="text/javascript">
        Ext.BLANK_IMAGE_URL="{!$Resource.ExtJS}/resources/images/default/s.gif"
    </script>

    <script type="text/javascript">
        Ext.onReady(function(){
            var allowinactive = ("{!allowinactiveselect}" == "true");
            var tree = new Ext.tree.TreePanel({
                renderTo: 'treediv',
                useArrows: true,
                autoScroll: true,
                animate: true,
                containerScroll: true,
                border: false,
                root: new Ext.tree.TreeNode({
                    text: 'All Campaigns',
                    expanded: true,
                    disabled: true,
                    id: 'camproot'
                }),
                listeners: {
                    // for the treepanel - but apparently not the menu - I can define a single event function for the whole thing
                    click: function(n) { {!fn}(n.id.substr(4)); }  // execute supplied callback
                }
            });
            // add the campaigns as tree nodes
            var parentNode;
            <apex:repeat value="{!CampaignTree}" var="c" id="treenodes">
                // add this Campaign as a menu item
                parentNode = tree.getNodeById(("{!c.parentid}" == "") ? "camproot" : ("NODE" + "{!c.parentid}"));
                parentNode.appendChild(new Ext.tree.TreeNode({id : ("NODE" + "{!c.id}"), text : "{!c.name}", leaf : "{!c.isleaf}",
                                                              // do not allow selecting inactive campaigns
                                                              disabled : !allowinactive && {!NOT(c.isActive)},
                                                              // if they are leafs, do not even show them...
                                                              hidden : !allowinactive && {!AND(c.isLeaf, NOT(c.isActive))}}));
            </apex:repeat>
        });
    </script>
    <div id="treediv"/>

</apex:component>