Semi-transparent QDrag pixmap

[Jugdish]

Hi,
I'm trying to make the pixmap on a QDrag object be semi-transparent, and not having much luck. Is it possible?

Here is the code I've got right now:

void MyTreeView::startDrag(Qt::DropActions supportedActions)
{
    QDrag *drag = new QDrag(this);
 
    QPixmap pixmap("/path/to/my/image.png");
    QPixmap alphaChannel(pixmap.width(), pixmap.height());
    alphaChannel.fill(QColor(128,128,128));
    pixmap.setAlphaChannel(alphaChannel);
 
    drag->setPixmap(pixmap);
 
    drag->exec(supportedActions);
}

void MyTreeView::startDrag(Qt::DropActions supportedActions)
{
    QDrag *drag = new QDrag(this);

    QPixmap pixmap("/path/to/my/image.png");
    QPixmap alphaChannel(pixmap.width(), pixmap.height());
    alphaChannel.fill(QColor(128,128,128));
    pixmap.setAlphaChannel(alphaChannel);

    drag->setPixmap(pixmap);

    drag->exec(supportedActions);
}

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However, setting the alpha channel on the pixmap just makes it look faded, but doesn't actually show the window contents underneath the pixmap, so it's not really transparent.