Ok, you would like to increase the splitting size for the region panel. To achieve this effect, the style code below should be overridden.
<style>
.layout-split-north{ border-bottom-width:24px;}
.layout-split-south{ border-top-width:24px;}
.layout-split-west{ border-right-width:24px;}
.layout-split-east{ border-left-width:24px;}
.layout-split-proxy-h { width: 24px; }
.layout-split-proxy-v { height: 24px; }
</style>
Make sure that the 'edge' property must be set to the corresponding size you want to grab it.
<body class="easyui-layout">
<div title="west" data-options="region:'west',split:true,edge:24" style="width:180px"></div>
<div data-options="region:'center'"></div>
</body>