diff --git a/src/ui/sand_box.c b/src/ui/sand_box.c
index 14db78c..b6898c5 100644
--- a/src/ui/sand_box.c
+++ b/src/ui/sand_box.c
@@ -60,13 +60,13 @@ static void on_bind_cb (GtkSignalListItemFactory *self, GtkListItem *my_list_ite
   gtk_label_set_text (GTK_LABEL (my_label), gtk_string_object_get_string (my_string_object));
 }
 
-static void on_selection_change (GtkSelectionModel* my_selection_model,  guint position, guint n_items, gpointer user_data)
+static void on_selection_change (GtkStringList *my_selection_model,  guint position, guint n_items, gpointer user_data)
 {
     printf("list size = %d    item type = %ld\
     position (premier élement ayant changé d'état) = %2d %7s\
     nombre d'éléments ayant changé d'état = %2d\n",
-        g_list_model_get_n_items (my_selection_model),
-        g_list_model_get_item_type(my_selection_model),
+        g_list_model_get_n_items (G_LIST_MODEL (my_selection_model)),
+        g_list_model_get_item_type(G_LIST_MODEL (my_selection_model)),
         position,
         gtk_string_list_get_string (my_selection_model, position),
         n_items );
@@ -74,19 +74,20 @@ static void on_selection_change (GtkSelectionModel* my_selection_model,  guint p
 
 //-------------------------------------------------------------------------------------------------------------------------------------------
 
-void on_activating_this_expander (GtkExpander *my_expander, gpointer my_data) {printf("on_activating  >  %s\n", gtk_string_object_get_string (my_expander));}
-void gtk_expander_set_child      (GtkExpander* expander, GtkWidget* child) {printf("gtk_expander_set_child ()   %s\n", gtk_string_object_get_string (child));}
+void on_activating_this_expander (GtkExpander *my_expander, gpointer my_data) {printf("on_activating exp.  >   %s\n", gtk_string_object_get_string (GTK_STRING_OBJECT(my_expander)));}
+void gtk_expander_set_child      (GtkExpander* expander, GtkWidget* child) {printf("gtk_expander_set_child ()   %s\n", gtk_string_object_get_string (GTK_STRING_OBJECT(child)));}
 
 GListModel *my_item_create_func (gpointer item, gpointer user_data)
 {
     printf("%s   ", gtk_string_object_get_string(item));
     gchar *my_child_array[] = {"1", "2", "3", NULL};
+    GtkStringList *my_child_string_list = gtk_string_list_new ((const char * const *) my_child_array);
 
-    if (gtk_string_object_get_string(item) == "zero") {
-        GtkWidget *my_expander = gtk_expander_new (my_child_array);
-        gtk_expander_set_child (my_expander, NULL);
-        on_activating_this_expander (my_expander, NULL);
-        return my_child_array;
+    if (strcmp(gtk_string_object_get_string(item), "zero")) {
+        GtkWidget *my_expander = gtk_expander_new (NULL);
+        /* gtk_expander_set_child (GTK_EXPANDER(my_expander), NULL); */
+        /* on_activating_this_expander (GTK_EXPANDER(my_expander), NULL); */
+        return G_LIST_MODEL (my_child_string_list);
     }
     else return NULL;
 }
@@ -99,12 +100,12 @@ static void and_now_let_s_climb_that_tree (GtkWidget *in_that_box)
     GtkMultiSelection *my_selection_model = gtk_multi_selection_new (G_LIST_MODEL (my_string_list));
 
     /* if (gtk_single_selection_get_selected_item (my_selection_model)) */
-    /*     gtk_selection_model_selection_changed (my_selection_model, 0, 1); */
+    /*     gtk_selection_model_selection_changed  (my_selection_model, 0, 1); */
 
     GtkListItemFactory *my_list_item_factory = gtk_signal_list_item_factory_new ();
     g_signal_connect (my_list_item_factory, "setup", G_CALLBACK (on_setup_cb), NULL);
     g_signal_connect (my_list_item_factory, "bind", G_CALLBACK (on_bind_cb), NULL);
-    if (1) { g_signal_connect (my_selection_model, "selection-changed", G_CALLBACK (on_selection_change), NULL);}
+    if (1) { g_signal_connect (G_LIST_MODEL (my_string_list), "selection-changed", G_CALLBACK (on_selection_change), NULL);}
 
 
 //  GListModel *(* GtkTreeListModelCreateModelFunc) (GObject* item, gpointer user_data)  //  remplacerait gtk_string_list_new() ?