The Home widget was added in 4.0 Beta 2. It's dead simple to add and the provided example code is a simple, minimal page of just a Scene and the Home Button. However, when I add the Home Button widget to my page which utilizes some other widgets (not sure if this has anything to do with it) my map view literally pans down and zooms in a bit on a nonstop repeating loop right on startup. Has anybody else seen this? Looks like some kind of Beta 2 bug.