trait MyScalatraStack extends ScalatraServlet with ScalateSupport {

  def lang() = params.getOrElse("lang", "en")

  notFound {
    contentType = null
    serveStaticResource() getOrElse {
      contentType = "text/html"
      NotFound(
      ssp(s"/$lang/error/404.ssp",
        "title" -> "Not Found 404",
        "layout" -> s"WEB-INF/templates/layouts/$lang/error.ssp",
        "lang" -> lang))
    }
  }
}