UpperCase Behavior

I was asked to create a TextBox input which has only UpperCase letters. After a bit of research, I have found this article which has inspired me to come up with this solution. As we all know that Behavior is a cool stuff in Silverlight 3, so I decided to use the concept from that article and create a Behavior which detects all the key and uppercase it. Feel free to download the source code and have a play with it.