How to embed QML toolbar and menubar into QMainWindow

I am using QWT library to plot data. It seems that it is not possible to embed QWidget into QML Quick 2. So, I decided to create QMainWindow as my main window and create its toolbar and menubar using Quick Controls. How should I embed that qml toolbar and menubar into QMainWindow?

You should create QML ApplicationWindow with QML MenuBar and ToolBar

main.qml

ApplicationWindow {
    visible: false
    menuBar: MenuBar {
        Menu {
            title: "Edit"
            MenuItem {
                text: "Cut"
            }
        }
    }
    toolBar: ToolBar {
        Row {
            anchors.fill: parent
            ToolButton {
                iconSource: "1.png"
            }
        }
    }
}

main.cpp

QApplication app(argc, argv);
QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:///main.qml")));

Then get pointer to your ApplicationWindow

QWindow *qmlWindow = qobject_cast<QWindow*>(engine.rootObjects().at(0));

Create window container, by using QWidget::createWindowContainer

QWidget *container = QWidget::createWindowContainer(qmlWindow);
container->setMinimumSize(qmlWindow->size());

And place container to the top of your widget

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