第一个ExtJS，在FireFox下显示不了，请各位指教

[SourceCode]
Ext.onReady(function() {
var northPanel = new Ext.Panel({
  region: 'north',
  autoLoad: {url: 'top.jsp'},
        split: false,
        height: 31,
        minSize: 31,
        maxSize: 31
});
var treePanel = new Ext.Panel({
        title: 'Menus',
        region: 'west',
        contentEl: 'layout_menu',
        split: true,
        border: true,
        collapsible: false,
        margins:'2 0 5 0',
        cmargins:'0 0 0 0',
        lines:false,
        autoScroll:true,
        autoHeight:false,
        width: 220,
        minSize: 220,
        maxSize: 220

});
mainPanel = new Ext.TabPanel({
  region:'center',
  resizeTabs:true,
  minTabWidth: 135,
  tabWidth: 135,
  margins:'2 0 5 0',
  cmargins:'0 0 0 0',
  activeTab: 0,
  items: {
      id:'welcome-panel',
      title: 'Index',
      autoLoad: {url: 'welcome.html',scripts:true}
     }
});
//mainPanel.activate('welcome-panel');
var viewport = new Ext.Viewport({
  layout:'border',
  items:[northPanel, treePanel, mainPanel]
});
var menudata = {
  "id":"rootmenu",
  "text":"System Maintaince",
  "singleClickExpand":true,
  "iconCls":"icon-pkg",
  "isClass":true,
  "children":[{
   "href":"maintaince/menus/list.jsp",
   "text":"Menus",
   "id":"test1",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  },{
   "href":"maintaince/menubuttons/list.jsp",
   "text":"MenuButtons",
   "id":"test2",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  },{
   "href":"maintaince/functioncode/list.jsp",
   "text":"FunctionUNITS",
   "id":"test3",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  },{
   "href":"maintaince/functionurl/list.jsp",
   "text":"FunctionURL",
   "id":"test4",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  },{
   "href":"maintaince/functioncolumn/list.jsp",
   "text":"FunctionDLL",
   "id":"test5",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  },{
   "href":"maintaince/functionlist/list.jsp",
   "text":"FunctionLIST",
   "id":"test6",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  },{
   "href":"maintaince/functionprint/list.jsp",
   "text":"FunctionPRINT",
   "id":"test7",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  },{
   "href":"maintaince/functionquery/list.jsp",
   "text":"FunctionQUERY",
   "id":"test8",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  }
  ]
};

var menudata2 = {
  "id":"rootmenu2",
  "text":"Database Maintaince",
  "singleClickExpand":true,
  "iconCls":"icon-pkg",
  "isClass":true,
  "children":[{
   "href":"maintaince/menus/list.jsp",
   "text":"Menus",
   "id":"test21",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  },{
   "href":"maintaince/menubuttons/list.jsp",
   "text":"MenuButtons",
   "id":"test22",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  },{
   "href":"maintaince/functioncode/list.jsp",
   "text":"FunctionUNITS",
   "id":"test23",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  },{
   "href":"maintaince/functionlist/list.jsp",
   "text":"FunctionLIST",
   "id":"test24",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  },{
   "href":"maintaince/menubuttons/list.jsp",
   "text":"MenuButtons",
   "id":"test25",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  },{
   "href":"maintaince/functioncode/list.jsp",
   "text":"FunctionUNITS",
   "id":"test263",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  },{
   "href":"maintaince/functionlist/list.jsp",
   "text":"FunctionLIST",
   "id":"test27",
   "edit":false,
   "leaf":true,
   "iconCls":"icon-cls"
  }
  ]
};


var Tree = Ext.tree;
var treePanel = new Tree.TreePanel({
   el:'layout_menu',
   border : false,
   rootVisible:true,
   animate:true,
   enableDD:false,
   lines:false,
   containerScroll: true,
   loader: new Ext.tree.TreeLoader({
    preloadChildren: true,
    clearOnLoad: true
   }),
   root: new Ext.tree.AsyncTreeNode({
    text:'CareSoft',
    id:'root',
iconCls:"icon-pkg",
    expanded:true,
    children:[menudata,menudata2]
    }),
   collapseFirst:false  
});
treePanel.render();
treePanel.expandAll();
new Tree.TreeSorter(treePanel,{folderSort:true});
treePanel.on("click", function(node, e){
  e.stopEvent();
  var _attr = node.attributes;
  var _href = _attr.href;
 
  if(node.isLeaf() && _href){
   var _id =  node.id;
   var _tab = mainPanel.findById(_id);
   if(_tab) {
    mainPanel.activate(_id);
    return;
   }

   mainPanel.add({
    id: _id,
    title: node.text,
    autoHeight: true,
margins:'5 5 5 5',
    autoLoad: {url: _href, scripts:true, params: 'id='+ _id +'&title=' + node.text },
    closable:true
   }).show();
  
  }
});
});
在IE中运行正常，但在 FireFox中菜单那部份是空白的，用FireBug可以看到有元素存在，但就是没有显示出来，错误信息没有，只有一些CSS方面的警告，请各位指教。
另外，个人感觉到看sample挺漂亮的，但自己做到应用程序中后，发现并不怎么样，感觉不是很清爽，还不如1.1中那个纯蓝色的感觉好，你们认为呢？

我也碰到了这个问题，
我用firebug是可以一层一层的点到显示不了的树的跟节点的
搞不懂怎么回事为什么没显示出来

试出来了
要给panel的容器定义相应的样式才可以显示，指定宽度高度就可以显示了