2 different mx namespaces?

Question

When creating a ViewStack component in FDT, the mx namespace URI is http://www.adobe.com/2006/mxml. The application component and spark components have their mx URI set to library://ns.adobe.com/flex/mx.

Any reason ViewStack and presumably other components haven't updated to the new URI?

Answer 1

You have basically answered your own question.

The ViewStack component is an mx component which does not have a Spark equivalent unlike many other components, hence it uses old mx namespace.

There are indeed other components such as DataGrid that will also still be using the old mx namespace.