The Widget Component is based around the concept of itemRenderer factories, just like the flex list and charting components. The goal is to use composition to separate behavior from content, so you can reuse the basic effect across many different applications and uses. In this case, the fluid animation as you move the mouse across the component is built by migrating the actual layout of the renderers towards the intended layout (as determined by the mouse position) over time. You can check out how it will look in action