i need to use Alt+Ctrl+arrow keys combination

[prasad.ece2]

windows 64-bit and Qt version is 4.8.5, i am using VS2010 by adding Qt plugin

void CBoxViewItem::keyPressEvent(QKeyEvent* f_event)
{
    if(f_event->KeyPress)
    {
        if(f_event->type() == QEvent::KeyPress)
        {
            if(f_event->modifiers().testFlag(Qt::AltModifier) && f_event->modifiers().testFlag(Qt::ControlModifier).)
            {
                switch(f_event->key())
                {
                    case Qt::Key_Left: 
                            qDebug()<<"Alt + Ctrl + Key_Left"; 
                            break;
                    case Qt::Key_Up: 
                            qDebug()<<"Alt + Ctrl + Key_Up"; 
                            break;
                    case Qt::Key_Right: 
                              qDebug()<<"Alt + Ctrl + Key_Right"; 
                               break;
                    case Qt::Key_Down:
                              qDebug()<<"Alt + Ctrl + Key_Down"; 
                              break;
                    default: 
                           qDebug()<<"Use Only Arrow Keys"; 
                           break;
                }
            }
            else
              qDebug()<<"Use Alt + Ctrl";
        }
    }
}

void CBoxViewItem::keyPressEvent(QKeyEvent* f_event)
{
    if(f_event->KeyPress)
    {
        if(f_event->type() == QEvent::KeyPress)
        {
            if(f_event->modifiers().testFlag(Qt::AltModifier) && f_event->modifiers().testFlag(Qt::ControlModifier).)
            {
                switch(f_event->key())
                {
                    case Qt::Key_Left: 
                            qDebug()<<"Alt + Ctrl + Key_Left"; 
                            break;
                    case Qt::Key_Up: 
                            qDebug()<<"Alt + Ctrl + Key_Up"; 
                            break;
                    case Qt::Key_Right: 
                              qDebug()<<"Alt + Ctrl + Key_Right"; 
                               break;
                    case Qt::Key_Down:
                              qDebug()<<"Alt + Ctrl + Key_Down"; 
                              break;
                    default: 
                           qDebug()<<"Use Only Arrow Keys"; 
                           break;
                }
            }
            else
              qDebug()<<"Use Alt + Ctrl";
        }
    }
}

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this is always going to default case only.