Draggable QPushButton Flicker?

Andaharoo

I'm a newbie with QT and I tried to implement a draggable QPushButton like so:

void DragButton::mousePressEvent(QMouseEvent* event)
{
    dragging = true;
}

void DragButton::mouseMoveEvent(QMouseEvent* event)
{
    if (dragging)
        move(event->pos());
}

void DragButton::mouseReleaseEvent(QMouseEvent* event)
{
    dragging = false;
}

Note: DragButton inherits QPushButton.
I loved this solution as it's very simple and intuitive. However it doesn't work like expected. Here are the results as a gif:
alt text
I haven't been able to find a good solution. What could be causing this flicker?

Eligijus

If you look at QMouseEvent class documentation you'll find this:
const QPoint & QMouseEvent::pos() const

Returns the position of the mouse cursor, relative to the widget that received the event.

If you move the widget as a result of the mouse event, use the global position returned by globalPos() to avoid a shaking motion.

So solution would be to use globalPos or relative coordinates to parent widget here's the implementation of the latter:

void DragButton::mouseMoveEvent(QMouseEvent *e)
{
    if(e->buttons() & Qt::LeftButton)
        move(mapToParent(e->pos()));
}