winjs.d.ts including typed event arguments

>  interface CustomEventEx<T> extends CustomEvent {
  detail: T;
  }
  interface LaunchActivatedEvent extends CustomEventEx<Windows.UI.WebUI.WebUILaunchActivatedEventArgs> {
  setPromise(promise: Windows.Foundation.IPromise<boolean>);
 type: string;
  }

Could be better in this code:
>WinJS.Application.addEventListener("activated", (ev: LaunchActivatedEvent ) => {…});