Dead-lock using Surface3D and QQmlApplicationEngine

// main.cpp
#include <QGuiApplication>
#include <QQmlApplicationEngine>

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);            QGuiApplication app(argc, argv);

   QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;    
    return app.exec();
}

// main.qml
import QtQuick 2.11 
import QtQuick.Controls 2.4 
import QtDataVisualization 1.3
ApplicationWindow { 
visible: true 
width: 640 
height: 480 
Surface3D{} 
}

// main.cpp

#include <QApplication>
#include <QQuickWidget>

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QApplication app(argc, argv);    

    QQuickWidget *view = new QQuickWidget;
    view->setSource(QUrl(QStringLiteral("qrc:/main.qml")));
    view->show();//    QQmlApplicationEngine engine;

    return app.exec();
}

// main.qml
import QtQuick 2.11 
import QtDataVisualization 1.3
 Item { 
     width: 640 
     height: 480 
     Surface3D{} 
}

// minimal.qbs
import qbsProject {
    minimumQbsVersion: "1.7.1"    CppApplication {
        Depends { name: "Qt.core" }
        Depends { name: "Qt.quick" }
        Depends { name: "Qt.quickwidgets" }
        Depends { name: "Qt.datavisualization" }        // Additional import path used to resolve QML modules in Qt Creator's code model
        property pathList qmlImportPaths: []        cpp.cxxLanguageVersion: "c++11"        cpp.defines: [
            // The following define makes your compiler emit warnings if you use
            // any feature of Qt which as been marked deprecated (the exact warnings
            // depend on your compiler). Please consult the documentation of the
            // deprecated API in order to know how to port your code away from it.
            "QT_DEPRECATED_WARNINGS",            // You can also make your code fail to compile if you use deprecated APIs.
            // In order to do so, uncomment the following line.
            // You can also select to disable deprecated APIs only up to a certain version of Qt.
            //"QT_DISABLE_DEPRECATED_BEFORE=0x060000" // disables all the APIs deprecated before Qt 6.0.0
        ]        files: [
            "main.cpp",
            "qml.qrc",
        ]        Group {     // Properties for the produced executable
            fileTagsFilter: "application"
            qbs.install: true
        }
    }
}

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQuickWindow>
QObjectList grabChildrenObjByClassName(QObject *parentObj, const QString & className){
    QObjectList objList;    
    foreach(QObject *obj, parentObj->children()){        
    if ((obj->metaObject()->className() == className ) ||    (obj->metaObject()->superClass()->className() == className )){
            objList << obj;
        }else{
            objList << grabChildrenObjByClassName(obj, className);
        }
    }
    return objList;
}

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);      QGuiApplication app(argc, argv);    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;    

if(QSysInfo::productType() == "windows"){// && QSysInfo::productVersion() == "10"){
        QObject *rootObj = engine.rootObjects().first();        
if (rootObj != nullptr){
            QQuickWindow *wnd = qobject_cast<QQuickWindow*>(rootObj);             if(wnd != nullptr){
                QString const className("QtDataVisualization::DeclarativeSurface");
                QObjectList surface3DList = grabChildrenObjByClassName(wnd, className);                QObject::connect(wnd, &QQuickWindow::visibleChanged, [surface3DList](bool flg){
                    if (!flg){
                        foreach(QObject *obj, surface3DList){
                            obj->deleteLater();
                        }
                    }
                });
            }
        }
    }    return app.exec();
}