public function updateCMSFields(\FieldList $fields) {

    parent::updateCMSFields($fields);

    //var_dump('pippo'); exit;

    /* SliderImage */
    $field = new UploadField('SliderImage');
    $field->setTitle('Immagine Slider');
    $fields->addFieldToTab('Root.Main', $field, 'File');

    /* PositionInScroller */
    $field = new DropdownField('PositionInScroller', 'Posizione nello Scroller', self::$positions);
    $field->setTitle('Posizione nello Slider');
    $fields->addFieldToTab('Root.Main', $field, 'SliderImage');
}