A question about using touchkit on gae

As tutorial said, TouchKitServlet is needed to be extended to use touchkit. we also need to extend the GAEVaadinServlet to deploy on the gae. So how to extend the two servlet?

​Thanks in advance

Is there any expert who can help to answer this question?
​I want to deploy the vaddin project on google app engine and I also want use touchkit in this project.
​How to deal with this situation?

I think I got the answer. As indicated in the touchkit tutorial, If you need to rather extend some other servlet, possibly in another add-on, it should be trivial to reimplement the functionality of TouchKitServlet, which is just to manage the TouchKit settings object.
​So I find the source code of TouchKitServlet​ on github, and reimplement the functionality in the child class of GAEVaadinServlet ​. It should be doable.