Hello
here is complete code where you can see small flicker at the end of dialog load.
Please reload page few times so you can see what i mean.
I used openDuration:800 so it can be better seen.
Additional, when you close dialog, you will see shadow after dialog is closed.
Thank you.
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  <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">
 <script type="text/javascript" src="/scripts/jquery-min.js"></script>
	<script type="text/javascript" src="/scripts/jquery.easyui.min.js"></script>
</head>
<body>
	<div id="dlg_login" Title="Please login" class="easyui-dialog" style="width:514px;height:250px;padding:7px 7px" modal="true" data-options="
    openAnimation:'fade',
    shadow:true,
    openDuration:800,
    closeDuration:400,
    closeAnimation:'fade',
    onBeforeClose:function(){
    var mask = $(this).data('window').mask;
    if (mask){
      mask.fadeOut();}
    },
    onClose:function(){
      $(this).panel('destroy');
    },
    onBeforeOpen:function(){
    var mask = $(this).data('window').mask;
    if (mask){
      mask.fadeIn();}
    }
	  ">
		<form id="form_login" method="post" novalidate></form>
	</div>
</body>
</html>