(UPDATED) A problem with using WA_Translucent background and QSizeGrip

[dzz007]

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow mw;

    mw.centralWidget()->setWindowFlags(Qt::SubWindow);

    QSizeGrip * sizeGrip = new QSizeGrip(mw.centralWidget());

    QGridLayout * layout = new QGridLayout(mw.centralWidget());


    mw.setWindowFlags(mw.windowFlags() | Qt::FramelessWindowHint);
    mw.setAttribute(Qt::WA_TranslucentBackground);

    qDebug() << sizeGrip->testAttribute(Qt::WA_TranslucentBackground);
    sizeGrip->setAttribute(Qt::WA_TranslucentBackground, false);
    qDebug() << sizeGrip->testAttribute(Qt::WA_TranslucentBackground);
    sizeGrip->setWindowFlags(sizeGrip->windowFlags() & ~Qt::FramelessWindowHint);

    sizeGrip->setWindowOpacity(1.0);
    mw.setWindowOpacity(1.0);

    layout->addWidget(sizeGrip, 0,0,1,1,Qt::AlignBottom | Qt::AlignRight);
    mw.centralWidget()->setStyleSheet("QWidget#a{border-image: url(:/f)}");
    mw.show();

    return a.exec();
}

Hello guys above is my code and the form it created is like this:

the problem is the size griper is composed by 9 little dot with a lot of hole in it and when my mouse hovered around on the griper it is like flashing between the <double arrow state> and <pointer state> (i guess it is caused by the TranslucentBackground attribute and those <translucent> dots in the gripper.

[Double-arrow]

[Pointer]

Could you help me please I would really appreciate that.