diff --git a/src/ui/tree.c b/src/ui/tree.c
index 1404a4a..ce5fb8e 100644
--- a/src/ui/tree.c
+++ b/src/ui/tree.c
@@ -60,7 +60,7 @@
 /******************************************************************************/
 
 
-/*
+/*   Old links   ( deprec ? )   To check.
 https://blog.gtk.org/2020/06/08/more-on-lists-in-gtk-4/
 https://docs.gtk.org/gtk4/section-list-widget.html
 https://en.wikibooks.org/wiki/GTK%2B_By_Example/Tree_View/Tree_Models
@@ -195,36 +195,6 @@ https://en.wikibooks.org/wiki/GTK%2B_By_Example/Tree_View/Columns_and_Renderer
  *............................................................................*/
 
 
-/*  M A N I F E S T    <<<    J'AI TOUT VIRÉ SAUF "make"    */
-/* ;; */
-/* ;; Dépendances sous GNU Guix */
-/* ;; */
-
-
-/* (specifications->manifest */
-/*   (list */
-/*       "bash" */
-/*       "coreutils" */
-/*       "gcc-toolchain" */
-/*       "pkg-config" */
-/*       "valgrind" */
-/*       "findutils" */
-/*       "gdb" */
-/*       "make"           <<<<<<<<<<<<   */
-/*       "gtk" */
-/*       "libxml2" */
-/*       "glew" */
-/*       "glfw" */
-/*       "libepoxy" */
-/*       "pango@1.90.0" */
-/*       "xorgproto" */
-/*       "glib" */
-/*       "mesa-headers" */
-/*       "mesa" */
-/*       "libadwaita" */
-/*    ) */
-/* ) */
-
 #include <unistd.h>
 #include <gtk-4.0/gtk/gtk.h>
 #include <glib-2.0/glib.h>
@@ -328,7 +298,8 @@ How to enable the 'tree.c' code (line 318) to create widgets in the main window
     - 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 branch [origin/dev/ui-simple-tree]\n");
+    but not here, in branch [origin/dev/ui-simple-tree]\n\n\
+/home/jean/01/GTK4/tree (learning)/The_Gnome_way/demos/gtk-demo\n");
 
     return button;
 }
diff --git a/src/ui/window.c b/src/ui/window.c
index 639558d..a240a0e 100644
--- a/src/ui/window.c
+++ b/src/ui/window.c
@@ -129,7 +129,7 @@ static void gem_graph_client_window_init(GemGraphClientWindow *self)
 }
 
 /*
-       Est-ce que c'est encore utile ?
+       Is this useful ?  (Does it FREE something ?)
 
   if (!gtk_widget_get_visible (my_window))
     gtk_widget_set_visible (my_window, TRUE);
@@ -139,9 +139,12 @@ static void gem_graph_client_window_init(GemGraphClientWindow *self)
 
 /* -------------------------------------------------------------------------- */
 
-static void create_my_list_model();
+static GtkWidget *create_my_list_model();
 GtkWidget *create_a_button_in_(GemGraphClientWindow *my_window);
 
+GtkWidget *my_tree = NULL;
+GtkWidget *my_button = NULL;
+
 void ui_set_stack(const char *mode)
 {
 
@@ -157,9 +160,11 @@ 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(window);
-            create_a_button_in_(window);
-            create_a_button(window); // <<< This function is in tree.c
+            if (! my_tree) my_tree = create_my_list_model(window);
+            if (! my_button) {
+                my_button = create_a_button_in_(window);  // <<<  The active function is in this file
+                create_a_button(window); // <<< This function is in tree.c and still sterile !!!   TODO
+            }
             break;
         case 'p':
             gtk_menu_button_set_icon_name(window->main_button_mode, "x-office-presentation-symbolic");
@@ -328,16 +333,12 @@ static GListStore *create_node_recursive (GListModel *model,  //  GListStore* g_
                                    GtkTreeIter *iter_parent,
                                    int depth)
 {
-  if (model == NULL)
-    printf("tree.c   >   print test() in :  create_node_recursive()\n");
-
   GtkTreeIter iter;
 
   if (model == NULL)
       model = gtk_tree_store_new (NUM_COLUMNS, G_TYPE_STRING);
 
   while (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);
 
@@ -350,22 +351,20 @@ static GListStore *create_node_recursive (GListModel *model,  //  GListStore* g_
   }
 
   if (depth == 0)
-    return G_LIST_MODEL(model); // can cast to GListModel or to GtkTreeStore ?
+    return G_LIST_MODEL(model); // Should we cast to GtkTreeStore ?
   else
     return NULL;
 }
 
-static void create_my_list_model(GemGraphClientWindow *my_window)
+static GtkWidget *create_my_list_model(GemGraphClientWindow *my_window)
 {
     GtkWidget *my_tree_box;
     GtkWidget *my_scrolled_window;
     GListStore *my_list_model = NULL;
-    GtkWidget *my_tree_view;
+    GtkWidget *my_tree_view = NULL;
     GtkCellRenderer *renderer;
 
     my_list_model = create_node_recursive (my_list_model, O, NULL, 0);
-    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);
@@ -392,5 +391,7 @@ static void create_my_list_model(GemGraphClientWindow *my_window)
     /* 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);
+
+    return my_tree_view;
 }