QQmlApplicationEngine/QWidget::createWindowContainer Interface drift

// main.cpp
#include <QtQml/QQmlApplicationEngine>
#include <QtWidgets/QApplication>
#include <QtQuick/QQuickWindow>
#include <QtWidgets>
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:///main.qml")));

    QWindow *qmlWindow = qobject_cast<QWindow*>(engine.rootObjects().at(0));
    QWidget *container = QWidget::createWindowContainer(qmlWindow);
    container->setMinimumSize(qmlWindow->size());
    QWidget *widget = new QWidget();

    QGridLayout *grid = new QGridLayout(widget);
    grid->addWidget(container,0,0);
    grid->addWidget(new QPushButton(widget),1,0);

    widget->show();

    return app.exec();
}

// main.qml
import QtQuick 2.0
import QtQuick.Layouts 1.3
import QtQuick.Controls 2.2
import QtQuick.Controls.Material 2.1
import QtQuick.Controls.Universal 2.1
import Qt.labs.settings 1.0

ApplicationWindow {
    visible:true
    color:"blue"
    header: ToolBar {
        RowLayout {
            anchors.fill: parent
            ToolButton {
                text: qsTr("‹")
                onClicked: stack.pop()
            }
            Label {
                text: "Title"
                elide: Label.ElideRight
                horizontalAlignment: Qt.AlignHCenter
                verticalAlignment: Qt.AlignVCenter
                Layout.fillWidth: true
            }
            ToolButton {
                text: qsTr("⋮")
                onClicked: menu.open()
            }
        }
    }

    StackView {
        id: stack
        anchors.fill: parent
    }
}

QQmlApplicationEngine

QWidget::createWindowContainer