/**
  * Updates the fields used in the cms
  * @param {FieldList} $fields Fields to be extended
  */
 public function updateCMSFields(FieldList $fields)
 {
     $fields->addFieldToTab('Root.Main', $field = new OptionsetField('DefaultPreviewMode', _t('UserPreviewPreference.DEFAULT_MODE', '_Default Preview Mode'), array('content' => _t('UserPreviewPreference.CONTENT_MODE', '_Content Mode: Only menu and content areas are shown'), 'split' => _t('UserPreviewPreference.SPLIT_MODE', '_Split Mode: Side by Side editing and previewing'), 'preview' => _t('UserPreviewPreference.PREVIEW_MODE', '_Preview Mode: Only menu and preview areas are shown')), Config::inst()->get('UserPreviewPreference', 'DefaultMode')));
     if (Session::get('ShowPreviewSettingChangeReload') == true) {
         $field->setError(_t('UserPreviewPreference.CHANGE_REFRESH', '_You have updated your preview preference, you must refresh your browser to see the updated setting'), 'warning');
         Requirements::javascript(CMSPREVIEWPREFERENCE_BASE . '/javascript/clear-local-preference.js');
         if ($this->isSaving == false) {
             Session::clear('ShowPreviewSettingChangeReload');
         }
     }
 }