Incorrect events dispatching after embedding QWindow in application.

After embedding QWindow (e.g. QQuickView) via QWidget::createWindowContainer(), some widgets miss mouse events.

I've distinguished (see applied video and code) one case, but there are others, I guess.

Adding window container to layout results in creating some new QWidgetWindows for some already existed widgets. If these windows overlap, events delivery can be incorrect.

I believe this is very important, because such behaviour stops developers from using Qt Quick 2 in mature apps based on widgets.