解決chrome瀏覽器無法得到window.showModalDialog傳回值

父頁面：

 function openwindows(){var obj = new Object();    //obj.ordernumlst=new Array("001","002","003");    var retval = window.showModalDialog("ordervideo.jsp?orderIds="+"0010,0020,0030",obj,"dialogWidth=500px;dialogHeight=500px");        //for chrome    if(retval == undefined) {    retval = window.returnValue;    }    alert(retval);      }

子頁面：

function onload(){    var flag = '<%=request.getAttribute("resultflag")%>';    if(flag == 'error') {    //for chrome   if(window.opener != undefined) {   window.opener.returnValue = flag;   } else {  window.returnValue=flag;   }    window.close();    }    else if (flag == 'save') {    //for chrome    if(window.opener != undefined) {    window.opener.returnValue = flag;    } else {  window.returnValue=flag;    }      window.close();    }}