QMimeData does not provide image/png if the imagedrag is in-process

class MyWidget : public QLabel
{
public:
 MyWidget(): QLabel(0) 
 {
  setMinimumSize(QSize(200, 200));
  setAcceptDrops(true);
 }

protected:
 virtual void dropEvent(QDropEvent* event) 
 {
  const QMimeData* mimeData = event->mimeData();
  qDebug() << "allFormats:" << mimeData->formats();
  const QString mime = "image/png";

  const QByteArray data = mimeData->data(mime);
  if(data.isEmpty()) 
  {
   qWarning("Bug: image/png data is not available when the drag is from the same process!");
  }

  QPixmap pix;
  if (!pix.loadFromData(data))
   qWarning("loading failed");
  setPixmap(pix);
  event->acceptProposedAction();
 }
 virtual void dragEnterEvent(QDragEnterEvent* event) 
 {
  event->accept();
 }
 virtual void dragMoveEvent(QDragMoveEvent* event) 
 {
  event->accept();
 }

 virtual void mouseMoveEvent(QMouseEvent*) 
 {
  QDrag* drag = new QDrag(this);
  QMimeData* mimeData = new QMimeData;
  mimeData->setText(text());
  QImage img("image.png");
  Q_ASSERT(!img.isNull());
  mimeData->setImageData(img);
  drag->setMimeData(mimeData);
  drag->exec();
 }
};

int main( int argc, char ** argv )
{
 QApplication app(argc, argv);
 MyWidget w1;
 w1.setText("Please drag from this widget");
 w1.show();
 MyWidget w2;
 w2.setText("Drop here");
 w2.show();
 return app.exec();
}