关于点击左边的菜单 在右边增加一个tab的问题???

var root=new Ext.tree.AsyncTreeNode({
        id:rootsid,
        text:"物流管理系统",
        loader:new Ext.tree.TreeLoader({
            url:"DATA/Dtree.aspx",
            listeners:{
                "beforeload":function(treeloader,node)
                {
                        treeloader.baseParams={
                        id:node.id,
                        method:'POST'
                        };
                }
            }
        })
    });

    var addTab = function(tabId, tabTitle, targetUrl, type) {
        //alert("add1"); alert(type);
        center.add({
            id: tabId + type,
            title: tabTitle,
            iconCls: 'tabs',
            html: "<iframe src='" + targetUrl + "'scrolling='no' frameborder=0 width=100% height=100%></iframe>",
            closable: true
        }).show();
    }
    var updateTab = function(tabId, title, url, type) {
        //alert("update1"); alert(tabId);
        var tab = center.getItem(tabId + type);
        if (!tab) {
            tab = addTab(tabId, title, url, type); //alert("ok");
        }
        else {
            tab.body.dom.innerHTML = "<iframe src='" + url + "'scrolling='no' frameborder=0 width=100% height=100%></iframe>";
        }
        center.setActiveTab(tab); //alert("update2");
    }

    var treenode = new Ext.tree.TreePanel({
        autoScroll: true,
        animate: true,
        root: root,
        rootVisible: false,
        border: false,
        animate: true,
        lines: true,
        //enableDD: true,
        containerScroll: true,
        listeners:
        {
            "click": function(node, event) {
                if (node.isLeaf()) {
                    event.stopEvent();
                    updateTab(node.id, node.text, 'HomePage.aspx?action=' + node.id, 'customer');
                }
                 else {
                    event.stopEvent();
                    node.toggle();
                }

            }
        }

    });