code: def dragMoveEvent(self, event):
          
          super(AbstractDragView, self).dragMoveEvent(event)
          if event.mimeData().hasFormat("application/x-protocol"):
              # find the nearest break to cursor
              self.dragline = self.cursor(event.pos())
              self.viewport().update()
              event.setDropAction(QtCore.Qt.MoveAction)
              event.accept()
          else:
              event.ignore()
docs: Determines if the widget under the mouse can recieve the drop