WebView in QuickWidget on macOS - broken??

[danryu]

I have a Qt6 widgets-based app with a tabbed interface, that needs to load a webpage in one tab.
To do this I create a QuickWidget and load a simple QML WebView.
(Working with Qt 6.3.0 on macOS 11 and Windows 11.)

However: the WebView does not display correctly on macOS, whereas it seems fine on Windows.
On macOS the webview appears as a blank white frame - but can be forced to appear buggily by adding a QMenu (see below).

I am not trying to do anything exotic or experimental, as far as I know.
In fact I have really just taken the quickwidget example project, and added a QML WebView.
This should work, right? So why doesn't it?

The working code below replicates the issue.
Download complete test project zip here: quickwidgetWeb.zip

---

main.cpp:

#include <QQuickWidget>
#include <QtWebView>
#include <QtWidgets>

class MainWindow : public QMainWindow {
    Q_OBJECT
public:
    MainWindow();
};

MainWindow::MainWindow()
{
    // need this on macOS to enable webview!?!
    QMenu *fileMenu = menuBar()->addMenu("someMenu");

    QTabWidget *tabWidget = new QTabWidget;
    setCentralWidget(tabWidget);

    const QSize size(400, 400);
    QTextBrowser *textBrows = new QTextBrowser();
    textBrows->setPlainText("Some plain text");
    tabWidget->addTab(textBrows, "Plain text");

    QQuickWidget *w = new QQuickWidget;
    w->resize(size);
    w->setResizeMode(QQuickWidget::SizeRootObjectToView);
    w->setSource(QUrl("qrc:quickwidget/webview.qml"));
    tabWidget->addTab(w, tr("WebView"));

    tabWidget->show();
}

int main(int argc, char **argv)
{
    QtWebView::initialize(); // at least necessary on Windows - webengine
    QApplication app(argc, argv);

    // this example and QQuickWidget are only functional when rendering with OpenGL
    QQuickWindow::setGraphicsApi(QSGRendererInterface::OpenGL);

    MainWindow mainWindow;
    mainWindow.show();

    return app.exec();
}

#include "main.moc"

---

webview.qml

import QtQuick 2.0
import QtWebView 1.1

Item {
    WebView {
        id: webView
        anchors.fill: parent
        url: "https://qt.io"
    }
}

---

quickwidget.pro

QT       += core gui quick widgets quickwidgets webview

TARGET = quickwidget
TEMPLATE = app

CONFIG += qmltypes
QML_IMPORT_NAME = QuickWidgetExample
QML_IMPORT_MAJOR_VERSION = 1

SOURCES += main.cpp

RESOURCES += quickwidget.qrc

This works fine on at least Windows. The non-webview tab is visible, and the web content displays when the webview tab is selected.

But on macOS the WebView is a blank white screen.

(NB: I had to set QT_WEBVIEW_PLUGIN=native in the Run environment to get past the "No WebView plug-in found!" error...)

Forcing (buggy) webview operation on macOS
If I set a QMenu in the MainWindow as shown in the main.cpp code example, then the WebView does display on macOS - BUT it seems that the OpenGL context sharing is broken? The WebView forces itself to the top layer, and can only be resized by maximizing and un-maximizing the window.

Can anybody help me get this working correctly?