Popup widget shown over a native widget not visible

A popup widget shown over a native widget (created from QWidget::createWindowContainer) stays on foreground even if it is raised.

See attachment to reproduce following the steps below:

• launch the app
• click on the first button Show popup
• the popup is not visible
• click on the second button Show native popup (using QWidget::raise)
• the popup is visible
• click on Hide me button
• the popup is hidden
• click again on the second button Show native popup (using QWidget::raise)
• the popup is not visible
• Now click on last button Show native popup (using QWindow::raise)
• the popup is displayed again

 This test case shows 2 issues:

• a non native popup widget can't be displayed above a native widget created from QWidget::createWindowContainer
• a native popup widget can't be displayed above its parent widget, if the parent widget has been raised before