protected function preloader($attrib)
    {
        $images = preg_split('/[\s\t\n,]+/', $attrib['images'], -1, PREG_SPLIT_NO_EMPTY);
        $images = array_map(array($this, 'abs_url'), $images);
        $images = array_map(array($this, 'asset_url'), $images);

        if (empty($images) || $_REQUEST['_task'] == 'logout') {
            return;
        }

        $this->add_script('var images = ' . self::json_serialize($images, $this->devel_mode) .';
            for (var i=0; i<images.length; i++) {
                img = new Image();
                img.src = images[i];
            }', 'docready');
    }