PHP弹出子窗口给父窗口传值

父窗口
addpayway.php

....................
<tr>
<td width="27%" align="right" class="but" >会员ID：</td>
<td width="219%" colspan="5" class="but" style="PADDING-LEFT: 10px" >
<script type='text/javascript'>
function openWindow()  
{  
window.open('User_Manage_select.php','_blank','height=450,width=470,status=no,toolbar=no,menubar=no,scrollbars=no,location=no');
}
</script>
<input name="UserID" type="text" id="UserID" onclick="openWindow()"></td>
</tr> 
....................

PopUp页面当中
User_Manage_select.php

....................
<input name="UserID<?php echo $rs->Fields(userid)->value;?>" type="hidden" id="UserID<?php echo $rs->Fields(userid)->value;?>" value="<?php echo $rs->Fields(userid)->value;?>">
....................

<script type="text/javascript">
function popup(xxx)  
{  
//alert(xxx);
//window.opener.document.getElementById("UserID").value=document.getElementById("UserID").value;
window.opener.document.getElementById("UserID").value=xxx;
window.close()  
}
</script>
        <input type="button" value=" 选 择 " name="button1" onClick="popup(<?php echo $rs->Fields(userid)->value;?>)" /></td>
....................