Piwik\Plugins\Actions\Actions::isCustomVariablesPluginsEnabled PHP Method

    public static function isCustomVariablesPluginsEnabled()
    {
        return \Piwik\Plugin\Manager::getInstance()->isPluginActivated('CustomVariables');
    }

 private function addSearchWidgets(WidgetsList $widgetsList, $controller)
 {
     $category = 'Actions_SubmenuSitesearch';
     $widgetsList->add($category, 'Actions_WidgetSearchKeywords', $controller, 'getSiteSearchKeywords');
     if (Actions::isCustomVariablesPluginsEnabled()) {
         $widgetsList->add($category, 'Actions_WidgetSearchCategories', $controller, 'getSiteSearchCategories');
     }
     $widgetsList->add($category, 'Actions_WidgetSearchNoResultKeywords', $controller, 'getSiteSearchNoResultKeywords');
     $widgetsList->add($category, 'Actions_WidgetPageUrlsFollowingSearch', $controller, 'getPageUrlsFollowingSiteSearch');
     $widgetsList->add($category, 'Actions_WidgetPageTitlesFollowingSearch', $controller, 'getPageTitlesFollowingSiteSearch');
 }