One of the great new additions in 3.5 is UIElement3D, which brings input, focus, and eventing to the 3D space. To use UIElement3D, you can use the two new classes that derive from it, ModelUIElement3D and ContainerUlElement3D, or you can create your own custom UIElement3D class.

In this blog post, Kurt creates a Sphere class by subclassing UIElement3D, and shows off some new 3D features in the process. Very cool!