Dunno if this is CORRECT or resolves the XSS issues that was the inciting reason why IH4 was updated to begin with.. This code works, but I need someone to validate if it resolves the XSS issue that was identified in IH4 v4.1.

Code:
<?php
/**mod Image Handler 4.3.2
 * Override Template for common/tpl_main_page.php
 *
 * @package templateSystem
 * @copyright Copyright 2005-2006 Tim Kroeger
 * @copyright Copyright 2003-2005 Zen Cart Development Team
 * @copyright Portions Copyright 2003 osCommerce
 * @license http://www.zen-cart.com/license/2_0.txt GNU Public License V2.0
 * @version $Id: tpl_main_page.php,v 2.0 Rev 8 2010-05-31 23:46:5 DerManoMann Exp $
 */
?>
<body id="popupAdditionalImage" class="centeredContent" onload="resize();">
<div>
<?php
    echo '<a href="javascript:window.close()">' . zen_image(strip_tags($_GET['products_image_large_additional']), $products_values->fields['products_name'] . ' ' . TEXT_CLOSE_WINDOW) . '</a>';
?>
</div>
</body>