gtk_tree_model_iter_nth_child (model, &iter, NULL, list_elt);
selection = gtk_tree_view_get_selection (GTK_TREE_VIEW (list));
gtk_tree_selection_select_iter (selection, &iter);
gtk_tree_model_iter_nth_child (model, &iter, NULL, list_elt);
selection = gtk_tree_view_get_selection (GTK_TREE_VIEW (list));
gtk_tree_selection_select_iter (selection, &iter);