code: def startDrag(self, dragData):
          
          # create the mime data
          mimeData = QMimeData()
          for key, value in dragData.items():
              mimeData.setData('application/x-%s' % key, wrapVariant(value))
          
          # create the drag instance
          drag = QDrag(self.scene().chart())
          drag.setMimeData(mimeData)
          drag.exec_()
docs: Starts a new drag with the inputed data.
          
          :param      dragData | <dict>