Implementing User interfaces for a specific platform can be quite frustrating when you try to migrate the result to a different platform. Even very small differences between implementations can spoil the effort.
Especially when prototyping it is much easier to start from a simple descriptive file and "interpret" the result.
Internationalization is supported using resource bundles. The "TestI18n" base class can be used as a utility to make sure that all entries in the platform independent description have a corresponding translation.