Цитата
void QAbstractItemView::currentChanged ( const QModelIndex & current, const QModelIndex & previous ) [virtual protected slot]
This slot is called when a new item becomes the current item. The previous current item is specified by the previous index, and the new item by the current index.
If you want to know about changes to items see the dataChanged() signal.
Наследуем QTableView и переопределяем слот