Try collapse and then expand left panel. It just gone
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8"/>
<title>Complex Layout - jQuery EasyUI Demo</title>
<!-- TreeGrid -->
<link rel="stylesheet" type="text/css" href="http://www.jeasyui.com/easyui/themes/default/easyui.css"/>
<link rel="stylesheet" type="text/css" href="http://www.jeasyui.com/easyui/themes/icon.css"/>
<link rel="stylesheet" type="text/css" href="http://www.jeasyui.com/easyui/themes/color.css"/>
<link rel="stylesheet" type="text/css" href="http://www.jeasyui.com/easyui/demo/demo.css"/>
<script type="text/javascript" src="http://code.jquery.com/jquery-1.6.min.js"></script>
<script type="text/javascript" src="http://www.jeasyui.com/easyui/jquery.easyui.min.js"></script>
<style>
html, body, table{
margin: 0;
padding: 0;
border: 0;
width:100%;
height:100%;
}
</style>
</head>
<body>
<table><tr><td>
<div class="easyui-layout" fit="true">
<div data-options="region:'north'" style="height:0px; display:none;"></div>
<div data-options="region:'south',split:true" style="height:50px;"></div>
<div data-options="region:'east',split:true" title="East" style="width:180px;">
<ul class="easyui-tree" data-options="url:'tree_data1.json',method:'get',animate:true,dnd:true"></ul>
</div>
<div data-options="region:'west',split:true" title="West" style="width:100px;">
<div class="easyui-accordion" data-options="fit:true,border:false">
<div title="Title1" style="padding:10px;">
content1
</div>
<div title="Title2" data-options="selected:true" style="padding:10px;">
content2
</div>
<div title="Title3" style="padding:10px">
content3
</div>
</div>
</div>
<div data-options="region:'center',title:'Main Title',iconCls:'icon-ok'">
<div class="easyui-tabs" data-options="fit:true,border:false,plain:true">
<div title="About" data-options="href:'_content.html'" style="padding:10px"></div>
<div title="DataGrid" style="padding:5px">
<table class="easyui-datagrid"
data-options="url:'datagrid_data1.json',method:'get',singleSelect:true,fit:true,fitColumns:true">
<thead>
<tr>
<th data-options="field:'itemid'" width="80">Item ID</th>
<th data-options="field:'productid'" width="100">Product ID</th>
<th data-options="field:'listprice',align:'right'" width="80">List Price</th>
<th data-options="field:'unitcost',align:'right'" width="80">Unit Cost</th>
<th data-options="field:'attr1'" width="150">Attribute</th>
<th data-options="field:'status',align:'center'" width="50">Status</th>
</tr>
</thead>
</table>
</div>
</div>
</div>
</div>
</td></tr></table>
</body>
</html>