class proxyReimpl : public QSortFilterProxyModel
{
protected:

 virtual bool lessThan(const QModelIndex &left, const QModelIndex &right) const
 {
     QVariant leftData = sourceModel()->data(left);
     QVariant rightData = sourceModel()->data(right);
     kDebug() << leftData.toString() << "\n" << rightData.toString() << "\n";
     return QSortFilterProxyModel::lessThan(left, right);
 }
}

class CallgrindFunctionsListTModel : public QAbstractItemModel
{
    Q_OBJECT

public:
    CallgrindFunctionsListTModel(CallgrindModel* model);

    QModelIndex               index(int, int, const QModelIndex &parent = QModelIndex()) const;
    QModelIndex               parent(const QModelIndex&) const;
    int                       rowCount(const QModelIndex &parent = QModelIndex()) const;
    int                       columnCount(const QModelIndex&) const;
    QVariant                  data(const QModelIndex &index, int role) const;
    QVariant                  headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const;
    CallgrindCallstackItem   *itemForIndex(const QModelIndex &index) const;

    iCachegrindItem::Columns  columnToPosInModelList(int col) const;

private:
//here are all my informations centralized
    CallgrindModel  *m_model;
};


HERE IS THE SNIPPER CODE THAT DECLARES THE MODEL:
    QAbstractItemModel    *fctTreeModel = m->getQAbstractItemModel(CallgrindModel::E_FCT_LIST);
    proxyReimpl *proxyFctTreeModel = new proxyReimpl();

    proxyFctTreeModel->setSourceModel( fctTreeModel );

    ui->FunctionsTreeView->setModel( proxyFctTreeModel );