Like I said AsWing is a really good option in RIA applications development, but there is another solution if you don’t like AsWing, called SPAS (Swing Package for ActionScript).

The Swing Package for ActionScript 3.0 (SPAS 3.0) provides a set of “lightweight” classes for making graphic user interfaces (GUI) on the Flash Plateform.

The SPAS 3.0 is fully compatible with both Flash 9 and Flex 2 applications.
It will be the starting point to extend Rich Internet Application to all applications wich are developed using Adobe’s Flash authoring products.

The SPAS 3.0 supply Flex 2 developers a real and efficient “java-like” set of GUI classes to wrap RIAs much better if they had to work with the native Flash Platform components.

Here is a sample application and some examples of using SPAS 3.0 . You can even find there a quick comparison of these plaftorms: AsWing A3 vs SPAS 3.0. Looks really nice