One of WPF’s most interesting additions to standard .NET programming has to be routed events. It took me a while to come up with an accurate way to visualize event routing. Karl Shifflett has made this learning process much easier for all by creating an excellent application called Routed Event Viewer. It allows you to watch as routed events tunnel their way down and bubble their way up the element tree, and even allows you to control which elements handle the events.
His blog post explains the Routed Event Viewer and provides a link to download it. Check it out!