EventFilter

self.GraphicsView.installEventFilter(self)

self.GraphicsView.mousePressEvent = self.qView_mousePressEvent

def eventFilter(self,obj,event):
    if obj is self.GraphicsView:
        if event.button() != QtCore.Qt.LeftButton:
            self.qView_mousePressEvent(event)
                return True
    return super(RigModuleUi, self).eventFilter(obj, event)

def qView_mousePressEvent(self,event):
    if (app.keyboardModifiers() == QtCore.Qt.AltModifier  and event.button() == QtCore.Qt.MiddleButton):
        self.GraphicsView.setCursor(QtCore.Qt.SizeAllCursor)
    if (app.keyboardModifiers() == QtCore.Qt.AltModifier  and event.button() == QtCore.Qt.RightButton):
        self.GraphicsView.setCursor(QtCore.Qt.SizeVerCursor)
    if event.button() == QtCore.Qt.LeftButton:
        QtGui.QGraphicsView.mousePressEvent(self.GraphicsView, event)