protected function setFormClass(FormInterface $oForm, $sFormLayout = self::LAYOUT_HORIZONTAL)
    {
        if (is_string($sFormLayout)) {
            $sLayoutClass = 'form-' . $sFormLayout;
            if ($sFormClass = $oForm->getAttribute('class')) {
                if (!preg_match('/(\s|^)' . preg_quote($sLayoutClass, '/') . '(\s|$)/', $sFormClass)) {
                    $oForm->setAttribute('class', trim($sFormClass . ' ' . $sLayoutClass));
                }
            } else {
                $oForm->setAttribute('class', $sLayoutClass);
            }
        }
        return $this;
    }