The docs for GtkTreeModel suggest iterating through the model using a while() loop, which makes the use of 'continue;' more error prone.

Perhaps the documentation should be updated with this pattern:

        gboolean valid;                
        for (valid = gtk_tree_model_get_iter_first (model, &iter);
             valid;
             valid = gtk_tree_model_iter_next (model, &iter))
        {
          ...
        }