Differences between Flex 3 and Flex 4 beta
The Flex 4 (codename: Gumbo) beta release is a major change from Flex 3. The Flex 4 beta introduces a new component and skinning architecture. As a Flex 3 developer, however, you will likely not encounter too many challenges when compiling Flex 3 applications with the Flex 4 beta, since a goal of the new release is to maintain backwards compatibility with Flex 3.
In this article, I will provide a general overview of the main objectives in the Flex 4 beta, architecture differences, and an introduction to changes in components, layouts, use of states, and effects. I’ll also answer some questions regarding what to expect when you compile your Flex 3 application in Flex 4 beta. This article will not cover all of the new features and functionality in Flex 4. For that information, see Matt Chotin’s What’s new in Flex 4 SDK betaarticle.
Throughout this document, the term Halo components refers to components originally included in Flex 3. The term Spark components refers to the new set of components in the Flex 4 beta.
Read more at: http://www.adobe.com/devnet/flex/articles/flex3and4_differences.html
