QTreeView and CheckBoxes

[FreeG]

Hi all, I would like to know if it is possible to have a TreeView widget displaying check boxes only on some nodes. Up to now I tried subclassing QAbstractItemModel in this way:

Qt::ItemFlags MyModel::flags ( const QModelIndex & index ) const
{
    if (index.isValid())
    {
        MyNode* node = static_cast<MyNode*>(index.internalPointer());
        if (node->needsCheckbox())
            return Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable;
    }
 
    return Qt::NoItemFlags;
}

Qt::ItemFlags MyModel::flags ( const QModelIndex & index ) const
{
    if (index.isValid())
    {
        MyNode* node = static_cast<MyNode*>(index.internalPointer());
        if (node->needsCheckbox())
            return Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable;
    }

    return Qt::NoItemFlags;
}

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but the only result I got is that all nodes have a checkbox, and the ones that fail the node->needsCheckbox() method looks greyed out.

Do I need a custom delegate?

Thanks in advance...