Draw rect when mouse is pressed

Hi,
Here is a piece of qt4 code written in python. Basically, a rectangle is painted when I press the mouse button. But the problem is the qgraphicsview will re-position the view, so the item painted is not under where the mouse is pressed. How do I solve this?

Code:

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from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys
 
class MapView(QGraphicsView):
 
    def __init__(self, parent = None):
        QGraphicsView.__init__(self, parent)
 
    def mousePressEvent(self, event):
        mousePos = self.mapToScene(event.pos())
        self.scene().addRect(mousePos.x(), mousePos.y(), 10, 10)
 
app = QApplication(sys.argv)
scene = QGraphicsScene()
view = MapView()
view.setScene(scene)
view.setFixedSize(400, 300)
view.show()
sys.exit(app.exec_())

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