An author here. What drop-downs are you referring to? We are a server-side framework (GWT = client-side). That means there is no need to implement a client-server protocol to access server-side resources, which, as application complexity increases, is a huge benefit.
JWt is also the web framework with best support for refactoring (no string-based bindings) and best support for OO design (you can specialize widgets easily).
A JWt application does not rely on JavaScript (unlike GWT) and can be properly indexed by a search engine (unlike GWT). That makes it more general purpose.
I love the fact that folks are still innovations and trying different patterns and approaches, even if that means fourfteen web frameworks for java.
Checking out the tutorial, just wanted to Congrats the JWt author on the release.