Adobe today released an early version of its latest Flex 4 SDK, "Gumbo," an open-source rich-client toolkit targeting the Flash VM. A key theme of Flex 4 is improved developer productivity, as well as enhanced collaboration capabilities between designers and developers.

Although the appearance of Flex components can already be affected with CSS stylesheets and with visual assets, such as images, and integration between FlexBuilder 3 and designer tools, such as PhotoShop already exists, Flex 4 aims to raise the level of developer-designer collaboration to an even higher level. To that effect, Adobe has designed a new architecture for skinning Flex components, and for integrating vector graphics with Flex applications. Improved support for application states and state transitions are also part of Flex 4.

In a demonstration of Flex 4 features, Eli Greenfield, an architect on the Flex SDK team, noted that:

[With Flex 4], a designer working on a Flex application is in complete control over the look and feel of the application... Once I've added the [various component] states into the skin file, I can go back up to my vector graphics [description], and tell [it] how exactly the individual properties of my graphics are going to change as those items go from state to state...

Matt Chotin, Flex SDK product manager at Adobe, added in a presentation on Flex 4 features that:

There are three primary themes for the next version of Flex, which we are code-naming Gumbo. The first is design in mind, second, developer productivity and, third framework evolution.

Design in mind is probably our number one features for this release, and we're doing a number of things around that theme. One of them is building the MXML language out to support more toolability... There is going to be a new language namespace, MXML2009. The old namespace, MXML 2006 will remain there, everything is still going to work, but 2009 is going to provide a couple of enhancements that will allow the tools to work much better.

Additionally, we're going to create a new file format, FXG. This is about describing vector graphics with XML in a way that closely matches what the Flash Player is capable of doing. You're going to see that in some of the tools. The beta versions of the latest Creative Suite tools already have that format. This is going to be one of the primary ways of transferring information between Thermo/Flex and various tools.

The biggest thing you'll see in the SDK itself is some of the new components and skinning architecture... It's a whole new architecture meant to allow easy skinnability of components, much cleaner separation... We're also working on improving states, effects, transitions, and layout...

What do you think of the main new features in Flex 4?