public function getModalCss(Vtiger_Request $request)
 {
     $parentCssInstances = parent::getModalCss($request);
     $cssFileNames = ['~libraries/jquery/jstree/themes/proton/style.css'];
     $modalInstances = $this->checkAndConvertCssStyles($cssFileNames);
     $cssInstances = array_merge($modalInstances, $parentCssInstances);
     return $cssInstances;
 }