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

protected:
    virtual void mouseMoveEvent(QMouseEvent*) {
        QDrag* drag = new QDrag(this);
        QMimeData* mimeData = new QMimeData;

        mimeData->setText(text());
        drag->setMimeData(mimeData);
        drag->exec();
    }
};

int main( int argc, char ** argv )
{
    QApplication app(argc, argv);
    MyWidget w1;
    w1.setGeometry(300,300,400,400);
    w1.setText("Test widget");
    w1.show();

    return app.exec();
}