Hi, I have a problem with QGraphicsItem:os (), or just I don't get it.

From the doc of QGraphicsItem:os (): "[...] this function returns the same as mapToParent(0, 0) [...]
That is true except when applying a transformation to the item that is not centered on it's origin; e.g.:

QTransform t;
t.translate(c.x(), c.y());
t.rotate(a);
t.translate(-c.x(), -c.y());
item->setTransform(t,true);

where a is an angle and c (in item's local coordinates) is a point different from (0,0).
For example:

transform(): QTransform(type=TxShear, 11=0.983923 12=0.178594 13=0 21=-0.178594 22=0.983923 23=0 31=13.7529 32=-52.7745 33=1)

pos(): QPointF(33, -246)
mapToParent(0,0): QPointF(46.7529, -298.774)
mapFromParent(pos()) : QPointF(-4.10658, 54.3822)


when I expect:

pos() == mapToParent(0,0)
(0,0) == mapFromParent(pos())


Any suggestions?
Thanks