[qt4 & Xp] resize columns of a QTreeView

[incapacitant]

I have this QtreeView 'table' based on a QStandardItemModel 'model'.

model->setHeaderData(0, Qt::Horizontal, tr("Mois"));
model->setHeaderData(1, Qt::Horizontal, tr("Facture"));

model->setHeaderData(0, Qt::Horizontal, tr("Mois"));
model->setHeaderData(1, Qt::Horizontal, tr("Facture"));

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I found how I can set the header text, but not how I can resize the columns.
No member in QTreeView does that. And the model should not be involved I guess.
resizeColumnTo Contents does not help me.

So I don't know how I can resize my columns in the view !!