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?
You have basically answered your own question.
The
ViewStackcomponent is anmxcomponent which does not have aSparkequivalent unlike many other components, hence it uses old mx namespace.There are indeed other components such as
DataGridthat will also still be using the old mx namespace.