- gtk_tree_model_get (model, iter1, MODEL_COL_NAME, &prov1, -1);
- gtk_tree_model_get (model, iter2, MODEL_COL_NAME, &prov2, -1);
+ gtk_tree_model_get (model, iter1,
+ MODEL_COL_NAME, &prov1,
+ MODEL_COL_ID_TYPE, &id_type1,
+ -1);
+ gtk_tree_model_get (model, iter2,
+ MODEL_COL_NAME, &prov2,
+ MODEL_COL_ID_TYPE, &id_type2,
+ -1);
+
+ retval = id_type_index (id_type2) - id_type_index (id_type1);
+ if (retval != 0)
+ goto end;