Swank, Подключи библиотеку. В head.php перед
"\n" . '</head><body>' . core::display_core_errors();Ставь
"\n" . '<script type="text/javascript" src="/papka/highslide-with-gallery.js"></script>
<link rel="stylesheet" type="text/css" href="/papka/highslide.css" />' .