Please post your inquiries in the correct forum section in order to be able to receive relevant replies.
You can debug the testWindow() function and check whether the following expression is null or not:
If it is null, then the widget is still not initialized, which can be caused by different reasons (e.g. the Window has not been loaded, or the document.ready event has not fired).
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.