diff --git a/src/ui/tree.c b/src/ui/tree.c
index 3cb0f38..1404a4a 100644
--- a/src/ui/tree.c
+++ b/src/ui/tree.c
@@ -322,12 +322,13 @@ GtkWidget *create_a_button(GemGraphClientWindow *my_window)
 
     g_signal_connect (button, "clicked", G_CALLBACK (print_hello), NULL);
 
-    printf("---------------------------------------------------------      tree.c  line 325\n\
+    printf("-----------------------------------------------------------      tree.c  line 325\n\
 Current obstacle : invalid use of incomplete typedef 'GemGraphClientWindow'\n\
 How to enable the 'tree.c' code (line 318) to create widgets in the main window ?\n\
-    (In the meanwhile, you can click the 'new button' in the GtkBox.)\n\
+    - The currently displayed tree code is at the end of file : window.c -\n\
+(In the meanwhile, you can click the 'new button' at the bottom of the GtkBox.)\n\n\
 NB  The speed makefile bug has been fixed in branch [devel]\n\
-    (but not here, in [origin/dev/ui-simple-tree])\n");
+    but not here, in branch [origin/dev/ui-simple-tree]\n");
 
     return button;
 }
diff --git a/src/ui/window.c b/src/ui/window.c
index be4e7fe..639558d 100644
--- a/src/ui/window.c
+++ b/src/ui/window.c
@@ -128,6 +128,15 @@ static void gem_graph_client_window_init(GemGraphClientWindow *self)
     //XXX TEMP ui_setup_glarea(window->run_glarea, window->run_controls);
 }
 
+/*
+       Est-ce que c'est encore utile ?
+
+  if (!gtk_widget_get_visible (my_window))
+    gtk_widget_set_visible (my_window, TRUE);
+  else
+    gtk_window_destroy (GTK_WINDOW (my_window));
+*/
+
 /* -------------------------------------------------------------------------- */
 
 static void create_my_list_model();
@@ -148,7 +157,7 @@ void ui_set_stack(const char *mode)
             break;
         case 'r':
             gtk_menu_button_set_icon_name(window->main_button_mode, "system-run-symbolic");
-            create_my_list_model();
+            create_my_list_model(window);
             create_a_button_in_(window);
             create_a_button(window); // <<< This function is in tree.c
             break;
@@ -320,7 +329,7 @@ static GListStore *create_node_recursive (GListModel *model,  //  GListStore* g_
                                    int depth)
 {
   if (model == NULL)
-    printf("tree.c   >   print test() in :  create_node_recursive()");
+    printf("tree.c   >   print test() in :  create_node_recursive()\n");
 
   GtkTreeIter iter;
 
@@ -328,7 +337,7 @@ static GListStore *create_node_recursive (GListModel *model,  //  GListStore* g_
       model = gtk_tree_store_new (NUM_COLUMNS, G_TYPE_STRING);
 
   while (current_item->label) {
-    if (1) printf("[%d] %s,   ", depth, current_item->label);
+    if (1) printf("[%d]-%s,  ", depth, current_item->label);
     gtk_tree_store_append (model, &iter, iter_parent);
     gtk_tree_store_set (model, &iter, STRING_COLUMN, current_item->label, -1);
 
@@ -346,10 +355,42 @@ static GListStore *create_node_recursive (GListModel *model,  //  GListStore* g_
     return NULL;
 }
 
-static void create_my_list_model()
+static void create_my_list_model(GemGraphClientWindow *my_window)
 {
+    GtkWidget *my_tree_box;
+    GtkWidget *my_scrolled_window;
     GListStore *my_list_model = NULL;
+    GtkWidget *my_tree_view;
+    GtkCellRenderer *renderer;
+
     my_list_model = create_node_recursive (my_list_model, O, NULL, 0);
-    printf("   <<    tree is OK\n");
+    printf("   <<    tree successfully created !\n");
+
+    my_tree_view = gtk_tree_view_new_with_model (my_list_model);
+    gtk_tree_view_set_headers_visible (GTK_TREE_VIEW (my_tree_view), FALSE);
+    gtk_tree_view_set_enable_tree_lines (GTK_TREE_VIEW (my_tree_view), TRUE);
+    gtk_widget_set_vexpand (my_tree_view, TRUE);
+    gtk_tree_selection_set_mode (gtk_tree_view_get_selection (GTK_TREE_VIEW (my_tree_view)),
+                               GTK_SELECTION_MULTIPLE);
+    gtk_tree_view_set_reorderable (GTK_TREE_VIEW (my_tree_view), TRUE);
+    g_object_unref (my_list_model);
+
+    renderer = gtk_cell_renderer_text_new (); g_object_set (renderer, "xalign", 0.0, NULL);
+    gtk_tree_view_insert_column_with_attributes (GTK_TREE_VIEW (my_tree_view), -1,
+                                "Col 0", renderer, "text", STRING_COLUMN, NULL);
+
+    my_scrolled_window = gtk_scrolled_window_new ();
+    gtk_scrolled_window_set_has_frame (GTK_SCROLLED_WINDOW (my_scrolled_window), TRUE);
+    gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (my_scrolled_window),
+                                  GTK_POLICY_AUTOMATIC,
+                                  GTK_POLICY_AUTOMATIC);
+    gtk_box_append (GTK_BOX (my_window->runlib_objects), my_scrolled_window);
+    gtk_widget_show(my_tree_box);
+
+    gtk_scrolled_window_set_child (GTK_SCROLLED_WINDOW (my_scrolled_window), my_tree_view);
+
+    /* expand all rows after the my_tree_view widget has been realized */
+    g_signal_connect (my_tree_view, "realize",
+                    G_CALLBACK (gtk_tree_view_expand_all), NULL);
 }