DataRectChanged
virtual void DataRectChanged(BRect oldDataRect,
DataRectChanged(oldDataRect, fDataRect);
fScrollSource->DataRectChanged(oldDataRect, fDataRect);
DataRectChanged(oldDataRect, fDataRect);
fScrollSource->DataRectChanged(oldDataRect, fDataRect);
virtual void DataRectChanged(BRect oldDataRect,
virtual void DataRectChanged(BRect oldDataRect,