The showModalDialog returns a Null solution in the Google browser

The return value of showModalDialog is available under IE and firefox, but Null is returned under Google. The solution is described below

The parent page:

 
function openwindows(){ 
var obj = new Object(); 

//Opens the modal subform and gets the return value
var retval = window.showModalDialog("ordervideo.jsp?rderIds="+"0010,0020,0030",obj,"dialogWidth=500px;dialogHeight=500px"); 

//for chrome 
if(retval == undefined) { 
retval = window.returnValue; 
} 
alert(retval); 
} 

Child pages:

 
function onload(){ 

//for chrome 
if(window.opener != undefined) { //The value of window.opener is not empty under Google browser and undefined under IE/firefox to determine if it is a Google browser
window.opener.returnValue = flag; // Method to assign a return value in the Google browser window.opener.close(); // This must be closed once, otherwise execute the following window.close() Unable to close the popup window because the popup window under the Google browser is new window 
} 

else { 
window.returnValue=flag; //This method of assignment is compatible with Internet explorer/firefox, but does not support the Google browser
} 
window.close(); 

}