public function showElementAction ($elementType, $key)
    {
        try
        {
            $element = $this->elementTypesModel->getElement($key, $elementType);

            if ((null === $element) || $element->isHidden())
            {
                throw new NotFoundHttpException("Element '{$key}' of type '{$elementType}' not found.");
            }

            $templateSuffix = $this->elementTypesModel->isFullPageElementType($elementType) ? "_fullpage" : "";

            return $this->twig->render("@core/show_element{$templateSuffix}.twig", [
                "element" => $element
            ]);
        }
        catch (\InvalidArgumentException $e)
        {
            throw new NotFoundHttpException("Unknown element type '{$elementType}'.", $e);
        }
    }