When a Web App Project is compiled, 6 permutations are compiled. What are those permutations, and what do they mean?
Google Web Toolkit uses deferred binding; it creates different versions of your application for different browser targets and localizations. Their FAQ response on Deferred Binding goes into more detail, but basically can be summed up in this quote:
For instance, if GWT supports 4 browsers, and you write your application in 3 languages, then GWT will generate a total of 12 different permutations of your application. During bootstrapping at runtime, GWT picks the appropriate permutation to show the user.