One of the really fun and productive things coming to Expression Blend 3 and Silverlight 3 is the concept of Behaviors.  In a nutshell, you will be able to drag/drop a Behavior in Blend 3 onto a UI Element on the design surface, and that will automatically inject runtime logic into that element. Behaviors aren’t a new concept, and there is even an equivalent in the ASP.NET AJAX world if you’ve played with creating custom controls in that universe.

Physics Behaviors!

One of the most fun examples I’ve seen using Behaviors was done by Pete Blois, a Program Manager on the Expression team at Microsoft. Pete and another developer created some Physics Behaviors which very closely mirror the Physics Helper Library I created for the Farseer Physics Engine. I first saw Pete demo the Physics Behaviors at the MVP Summit a few weeks ago, and my jaw dropped at the similarities! Pete & Co.’s Physics Behaviors use the Box2D Physics Engine.

Getting Started with Behaviors

If you’re playing with Silverlight 3 and Blend 3, why wait? You can play with Behaviors today! Note this is all Beta level stuff, so be prepared for some hiccups along the way

Pete’s MIX Session – Pete Blois gave a great overview of Behaviors in this MIX 09 session.

Using Behaviors – A quick Walkthrough by Kirupa on how to use behaviors! Pay special attention to where you find the assembly Microsoft.Expression.Interactivity.dll - you'll need that for the next link.

MIX Behavior Pack – this contains the Physics Behaviors, as well as a bunch of others.

Creating New Behaviors

It turns out it’s pretty easy to create your own behaviors, and I’ll be covering this in a later blog post. But if you can’t wait, just download the MIX Behavior Pack and have a look at the Behaviors, all of their source code is included!