在ie8下，点击左边的树形导航栏，在右面板中，弹出相对应的内容，这些内容都写在iframe中，但是在ie8下，需要随便在页面上点击一下鼠标，才能显示内容，换成Firefox和ie7，都能正常的显示，求各位高手解答。
这是部分代码
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<%@ page contentType="text/html;charset=UTF-8"%><%@ include file ="/includes/jsp/init.jsp"%><!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><title>系统首页</title><!-- 引入基础的JS和CSS文件 --><%@ include file="/common/meta_ext.jsp"%><link href="/resources/css/index/index.css" rel="stylesheet" type="text/css"/><link href="/resources/css/index/index-treetab.css" rel="stylesheet" type="text/css"/><script src="/resources/js/index/index.js" type="text/javascript"></script><script src="/resources/js/ext/ux/Portal.js" type="text/javascript"></script><script src="/resources/js/ext/ux/PortalColumn.js" type="text/javascript"></script><script src="/resources/js/ext/ux/Portlet.js" type="text/javascript"></script><script src="/resources/js/ext/ux/TabCloseMenu.js" type="text/javascript"></script><script src="/resources/js/jquery/jquery.js" type="text/javascript"></script><script type="text/javascript">var opername='<%= user.getOperName()%>'; Ext.onReady(function(){ Ext.QuickTips.init(); //定义页头var header =new Ext.Panel({ border: false, layout: 'anchor', region: 'north', margins: '0 0 1 0', height: 100, items: [{ xtype: 'box', el: 'header', border: false, anchor: 'none -1' }], bbar: [ '->','-',{ xtype: 'splitbutton', text: '当前用户：'+opername, iconCls: 'icon-user-male', menu: [{ text:'修改用户基本信息', handler:help },{ text:'修改密码', handler:help }] },'-',{ text: '退出系统', iconCls: 'icon-exit', handler: relogin },'-'] }); //定义树菜单控件var tree =new Ext.tree.TreePanel({ useArrows: true, animate: true, enableDD: false, border: false, rootVisible: false, autoScroll: true, containerScroll: true, bodyStyle: 'padding:3px', root: new Ext.tree.AsyncTreeNode({ id: '-1', draggable: false, leaf: false }), loader: new Ext.tree.TreeLoader({ dataUrl: '/extAction.do?task=getTreeJson', listeners: { "beforeload": function(treeLoader, node){ treeLoader.baseParams.id = node.id; } } }) }); tree.on('click', function(node, e){ if(node.id !=-1&& node.attributes.url !=null){ openUrl(node.attributes.url); }else{ tree.expandPath(node.getPath()); } }); tree.on('beforeexpandnode', function(node){ if(node.id!=-1&&node.getDepth()==1){ tree.collapseAll(); } }); //定义树菜单面板var treePanel =new Ext.Panel({ region: 'west', collapsible: true, autoScroll: true, split: true, iconCls: 'icon-expand-all', title: '菜单导航', 220, maxWidth: 300, minWidth: 220, margins: '0 0 3 5', items: tree }); //定义主界面整体布局var viewPort =new Ext.Viewport({ layout: 'border', items: [header, treePanel, new Ext.Panel({ id:'main_panel', region: 'center', 400, contentEl:'con' })] }); }); function openUrl(url){ if(url!=null){ document.getElementById('misFrame').src = url; } } </script></head><body><div id="header" style="background-image:url(/resources/images/background/header6.jpg);background-repeat: repeat-x;"><img src="/resources/images/background/toplf5.jpg"/></div><div id="con" style="height:100%;"><iframe src="http://www.baidu.com" id="misFrame" name="misFrame" width="100%" height="100%" frameborder="0"></iframe></div></body></html>=====================================================答案：在<head>中间加一句<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE7" />