Extjs layout border 一片空白解决办法。

Ext.onReady(main);

function main()
{
new Ext.Viewport({
enableTabScroll:true,
layout:"border",
items:
[{
title:"面板",
region:"north",   //顶部面板
height:50,
html:'<h1>网站后台管理系统</h1>'
}, {
title:"菜单",
region:"west",    //左边菜单项，有按钮可控制伸缩的
width:200,
collapsible:true,
html:"菜单栏"
}, {
xtype:"tabpanel",   //选项卡
region:"center",
items:
[
{title:"面板1",html:'<h1>面板1内容</h1>'},
{title:"面板2",html:'<h1>面板2内容</h1>'},
{title:"面板3",html:'<h1>面板3内容</h1>'},
]
}]
});
};