public static function removeCssClass(&$options, $class)
    {
        if (isset($options['class'])) {
            $classes = array_unique(preg_split('/\s+/', $options['class'] . ' ' . $class, -1, PREG_SPLIT_NO_EMPTY));
            if (($index = array_search($class, $classes)) !== false) {
                unset($classes[$index]);
            }
            if (empty($classes)) {
                unset($options['class']);
            } else {
                $options['class'] = implode(' ', $classes);
            }
        }
    }