Qt Designer: QDesignerContainerExtension: page title mechanism is broken

Pages added within designer are not correctly rendered.

Steps to reproduce:

• add MultiPageWidget in your project with designer
• change page title
• compile and start your application
• the page title is lost, label is defaulting to "Page 1"

Since the aim of this example is to show how a container widget works, it leaves developer without any clue on how to implement page settings correctly.

After inspection of the moc, the title is saved in the windowTitle property.
Pages are inserted in the setupUI() call, but at that point the windowTitle has not yet been set. Hence the title is lost.