rem: GtkTreeIter iter;
add: GtkTreeIter iter, parent, child;
context: item_toggled (GtkCellRendererToggle *cell,	      gchar                 *path_str,	      gpointer               data){  GtkTreeModel *model = (GtkTreeModel *)data;  GtkTreePath *path = gtk_tree_path_new_from_string (path_str);  GtkTreeIter iter;  gboolean toggle_item;  /* get toggled iter */  gtk_tree_model_get_iter (model, &iter, path);  gtk_tree_model_get (model, &iter, 		      PAYMENT_METHODS_DEFAULT_COLUMN, &toggle_item, 		      -1);  /* do something with the value */  toggle_item ^= 1;  /* set new value */  gtk_tree_store_set (GTK_TREE_STORE (model), &iter, 		      PAYMENT_METHODS_DEFAULT_COLUMN, toggle_item, 		      -1);  /* clean up */  gtk_tree_path_free (path);}