Creates the drag event for this item.
        
        :param      event | <QMousePressEvent>

def mousePressEvent(self, event):
        """
        Creates the drag event for this item.
        
        :param      event | <QMousePressEvent>
        """
        ddata = self.dataset().dragData()
        if ddata:
            self.startDrag(ddata)
        
        super(XChartDatasetItem, self).mousePressEvent(event)