QAbstractItemView::dataChanged / update on single cells not working in Qt 4.5.3

dataChange on single cells calls update.
but the funtion never calls the update on the rect, because the rect never intersects the viewport geometry.
I think the geometry give an the geometry to the parent widget and visualRect the geometry to the viewport. so that the two rect shifted by header sizes.

i use an own implementation of headerview, but also with the default tablewidget this does not working.
the only workaround is to send an dataChanged for more than one cell, but this updates all cells.

//4.5.3
void QAbstractItemView::update(const QModelIndex &index)
{
Q_D(QAbstractItemView);
if (index.isValid())

{ const QRect rect = visualRect(index); //this test is important for peformance reason //For example in dataChanged we simply update all the cells without checking //it can be a major bottleneck to update rects that aren't even part of the viewport if (d->viewport->geometry().intersects(rect)) d->viewport->update(rect); }

}

//4.5.2
void QAbstractItemView::update(const QModelIndex &index)
{
Q_D(QAbstractItemView);
if (index.isValid())
d->viewport->update(visualRect(index));
}