To create a panel with absolute attribute, a style property must be applied to the outer panel object. Try the following code:
<div id="helpPanel" class="easyui-panel" style="padding:10px;background:#FFFFFF;" data-options="title:'HELP',closable:true,closed:true,
style:{
position:'absolute',
left: 50,
top: 50
}"></div>
As an absolute panel, the width and height need to be set before display on screen.
$('#helpPanel').panel('open').panel('resize',{
width:$(window).width()-100,
height:$(window).height()-100
});