QWebEngineView with transparent bg always on top

[jjoorrpp]

What I expect:

• QWebEngineView with a translucent background

• QWidget overlay on QWebEngineView

Codes are:

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    QMainWindow mainWindow;

    QWebEngineView view(&mainWindow);
    view.setUrl(QUrl("https://www.qt.io"));
    view.setGeometry(50, 50, 300, 300);

    view.page()->setBackgroundColor(Qt::transparent); /// <- #1 make web engine view bg transparent

    QWidget overlay(&mainWindow);
    overlay.setGeometry(0, 0, 100, 100);
    overlay.raise(); /// <- #2 make overlay widget on top
    overlay.setStyleSheet("background:red");

    mainWindow.resize(400, 400);
    mainWindow.show();
    return app.exec();
}

Result is:

Problem is:
QWebEngineView overlayed on QWidget.
QWidget cannot overlay on QWebEngineView when QWebEngineView has transparent bg.

How to solve it?

ps: problem appears on Windows 10, Qt 5.15.0 with msvc2019

[jjoorrpp]

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