There is no Qt:SortRole

For exmple:

bool QTableWidgetItem::operator<(const QTableWidgetItem &other) const
{
    const QVariant v1 = data(Qt::DisplayRole), v2 = other.data(Qt::DisplayRole);
    return QAbstractItemModelPrivate::variantLessThan(v1, v2);
}

Suppose, We have column "event time" which is storing time_t as Qt::SortRole and "Today","last week" and so on in Qt::DisaplayRole
( Now, I use hidden column with time_t just for correct sorting )

It will be nice, if Qt::SortRole role data may be specified. When no such role set, standard implementation should user Qt::DisplayRole.

Also, please update Documentation in QTableWidget and maybe other places where you are talking about sorting, that sorting is based on Qt::DisplayRole.