I have a QMainwindow with a QToolBar at top and a QStatusbar at bottom. CentralWidget contains a QGraphicsView.

If I just add QT += webenginewidgets in the pro file (without actually using it) and I set the QGraphicsView to use openGL with

        QOpenGLGLWidget *gl = new QOpenGLWidget();
        QSurfaceFormat format;
        format.setSamples(4);
        gl->setFormat(format);
        gl->makeCurrent();
        setViewport(gl);

Then the toolbar and the statusbar appear twice, one normal and the other flipped vertically and horizontally.

Without openGL in the qgraphicsview all look normal.

Same app runs fine on Windows.

Thanks
Philippe