protected function getInvokingElement()
    {
        if ($this->invokingElement)
            return $this->invokingElement;
        // __this is elementName:eventHandlerName
        $elementAndEventName = Openbizx::$app->getClientProxy()->getFormInputs("__this");
        if (!$elementAndEventName)
            return array(null, null);
        list ($elementName, $eventHandlerName) = explode(":", $elementAndEventName);
        $element = $this->getElement($elementName);
        $eventHandler = $element->eventHandlers->get($eventHandlerName);
        $this->invokingElement = array($element, $eventHandler);
        return $this->invokingElement;
    }