demo.htm<input type="text" name="txt">
<input type="button" onclick="window.open('in.htm')" value="Open">in.htm<script>
function CloseOpen() {
if(event.clientX<=0 && event.clientY<0) {
window.opener.document.all.txt.value=document.all.son.value;
}
}
</script>
<body onunload="CloseOpen()">
<input type="text" name="son">