class PianoKey(QtGui.QGraphicsPolygonItem):
    def __init__(self, *args):
        super(PianoKey, self).__init__(*args)
    def hoverEnterEvent(self, event):
        print event
        return super(lkey, self).hoverEnterEvent(event)

gview = QtGui.QGraphicsView()
gview.setScene(piano.PianoScene())
gview.setMouseTracking(True)

class PianoScene(QtGui.QGraphicsScene):
    def mouseMoveEvent(self, event):
        if event.type()==QtCore.QEvent.GraphicsSceneMouseMove:
            print str(self.itemAt(event.scenePos()))
            s = str(event.scenePos().x())+', '+str(event.scenePos().y())
            self.lb.setText(s)
        return super(PianoScene, self).mouseMoveEvent(event)