Can't use stacked layout as a child of another layout

Let's say I would like to construct the following application:

- Central widget (QWidget with QVBoxLayout)
--- Widget #1 (QWidget)
--- Widget #2 (QWidget)
--- Widget #3 (QWidget with QStackedLayout)

The result: Widget #3 is the only visible widget. For example QWebEngineView has QStackedLayout by default, so it can not be used this way.