Extending MXML Components with MXML

I've recently needed to create an MXML component that enables users to add MXML
content into it. The solution is simple yet powerful and provides a way to easily create
extendable MXML components.
In the example below, the component holds a ButtonBar and a ViewStack.
The ViewStack itself is a property of the component that can be added in MXML
when using the component. Each user can add as many views as he needs and
the ButtonBar displays the views.

Code can be found here.