<form method="post" name="myform">
<input type="text" name="param" />
<input type="submit" />
</form>
<script type="text/javascript">
function test() {
	w.document.write("<script>window.opener.document.myform.param.value=123</" + "script>");
	w.document.close();
}
var w=window.open();
setTimeout('test()',0);
</script>