Damage of window decorations' right and bottom edges are outside the surface

const QImage &QWaylandAbstractDecoration::contentImage()
{
    Q_D(QWaylandAbstractDecoration);
    if (d->m_isDirty) {
        //Update the decoration backingstore

        const int scale = waylandWindow()->scale();
        const QSize imageSize = window()->frameGeometry().size() * scale;
#ifdef Q_OS_SYLIXOS  // This code should be optimized, it not only for porting SylixOS.
        if ((d->m_decorationContentImage.format() != QImage::Format_ARGB32_Premultiplied) || 
            (d->m_decorationContentImage.size()   != imageSize)) {
            d->m_decorationContentImage = QImage(imageSize, QImage::Format_ARGB32_Premultiplied);
            d->m_decorationContentImage.setDevicePixelRatio(scale);
            d->m_decorationContentImage.fill(Qt::transparent);
            this->paint(&d->m_decorationContentImage);
            // // Should the parameter here be like this? Not frameGeometry() but geometry()!
            QRegion damage = marginsRegion(window()->geometry().size(), window()->frameMargins());
            for (QRect r : damage)
                waylandWindow()->damage(r);
        }
#else
        d->m_decorationContentImage = QImage(imageSize, QImage::Format_ARGB32_Premultiplied);
        d->m_decorationContentImage.setDevicePixelRatio(scale);
        d->m_decorationContentImage.fill(Qt::transparent);
        this->paint(&d->m_decorationContentImage);

        QRegion damage = marginsRegion(window()->frameGeometry().size(), window()->frameMargins());
        for (QRect r : damage)
            waylandWindow()->damage(r);
#endif
        d->m_isDirty = false;
    }

    return d->m_decorationContentImage;
}