Detection area of for cursors on QGraphicsItems is offset on OSX

After setting a cursor on a graphics item, the cursor is changed in an area slightly (about 2 pixels) offset from the actual shape of the item. For example:

        QGraphicsScene* gs = new QGraphicsScene();
	QGraphicsView* gv = new QGraphicsView(gs, 0);
	QGraphicsRectItem* item = new QGraphicsRectItem(QRectF(0, 0, 10, 10), 0, gs);
	item->setPos(100,100);
	item->setCursor(Qt::SizeFDiagCursor);
	item->show();
	gv->show();

Move the cursor around this box. The area where the cursor changes is about -2,-2 offset from the drawn shape.