maskClick 不触发

<header class="mui-bar mui-bar-nav">  
        <a class="mui-action-back mui-icon mui-icon-left-nav mui-pull-left"></a>  
        <h1 class="mui-title">标题</h1>  
    </header>  
    <div class="mui-content">  
        <a href="#popover" class="mui-btn mui-btn-primary mui-btn-block">打开弹出菜单</a>  
        <div class="mui-popover" id="popover">  
            <ul class="mui-table-view">  
                <li class="mui-table-view-cell"><a href="#">Item1</a></li>  
                <li class="mui-table-view-cell"><a href="#">Item2</a></li>  
                <li class="mui-table-view-cell"><a href="#">Item3</a></li>  
            </ul>  
        </div>  
    </div>  
    <script type="text/javascript" charset="utf-8">  
        mui.plusReady(function(){  
            alert('why');  
            var self = plus.webview.currentWebview();  
            self.addEventListener('maskClick',function(){  
                alert('maskClick is activated');  
            });  
        });  
    </script>

点击popover外面的区域没法触发maskClick