Copy paste:

Code:
<html>
<head>
<title>Simple Form</title>
</head>
<body>
<script language="JavaScript">
<!--
function windowOpen() {
    var
myWindow=window.open('popup.htm','windowRef','width=200,height=200');
    if (!myWindow.opener) myWindow.opener = self;
}
//--></script>
<input name="openPopup" type="button" id="openPopup"
onClick="Javascript:windowOpen();" value="Get Value" />
<form name="form1" id="form1" method="post" action="">
    <input type="text" value="" name="output"></input>
</form>
</body>
</html>

THE POPUP FORM (popup.htm)
<html>
<head>
<title>The Popup</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
</head>

<body>
<script language="JavaScript"><!--
function updateOpener() {
    window.opener.document.forms[0].output.value =
document.forms[0].inputX.value;
    window.close();
}
//-->
</script>
EventId:
<input type="text" name="inputX"></input>
<input name="Close" type="submit" id="Close"
onClick="Javascript:updateOpener()" value="Close"></input>
</body>
</html>