Good to know this. As I said, my money was on a problem with the mapper, but with the exception of the problem you identified, it all looked OK. The mapper *should* keep the view updated whenever there is a change to the model, and calling setData() is exactly that.

I am curious now - if you had derived your model from QAbstractTableModel, would the QHPieModelMapper have automatically used the headers from that? QStandardItemModel *could be* used to represent tabular data, whereas QAbstractTableModel *always* does so the mapper could be assured of finding a horizontal header row.

Thanks for following up by posting your solution.