diff --git a/demos/gtk-demo/tree_store.c b/demos/gtk-demo/tree_store.c
index fda6319..34e8dee 100644
--- a/demos/gtk-demo/tree_store.c
+++ b/demos/gtk-demo/tree_store.c
@@ -66,6 +66,13 @@ static TreeItem B[] = {{ "E", E }, { "F", F }, { "G", G }, { NULL }};
 static TreeItem A[] = {{ "C", C }, { "D", D }, { NULL }};
 static TreeItem R[] = {{ "A", A }, { "B", B }, { NULL }};
 
+static GtkTreeModel *
+iterate_node(GtkTreeStore *model, TreeItem *parent)
+{
+  printf("parent->label : %s\n", parent->label);
+  return GTK_TREE_MODEL (model);
+}
+
 static GtkTreeModel *
 create_model (void)
 {
@@ -78,7 +85,6 @@ create_model (void)
   while (item_0->label)
     {
       TreeItem *item_1 = item_0->children;
-
       gtk_tree_store_append (model, &iter, NULL);
       gtk_tree_store_set (model, &iter, COLUMN_0, item_0->label, -1);
 
@@ -92,6 +98,7 @@ create_model (void)
           TreeItem *item_2 = item_1->children;
             while (item_2->label) {
             GtkTreeIter child_child_iter;
+            iterate_node(model, item_2);
             gtk_tree_store_append (model, &child_child_iter, &child_iter);
             gtk_tree_store_set (model, &child_child_iter, COLUMN_0, item_2->label, -1);