[Interest] qt_add_qml_module and not embedding QML files

[Ulf Hermann]

> 2. The app is primarily widgets, but we use QML inside QQuickView, 
> inside container widgets. So when the app starts 3 or 4 QML engines are 
> created.

That is a problem. The preview can only handle a single QML engine so 
far. You should see the following error message:

"<n> QML engines available. We cannot decide which one should load the 
component."