diff --git a/demos/gtk-demo/tree_store.c b/demos/gtk-demo/tree_store.c
index 944bc2c..65cecec 100644
--- a/demos/gtk-demo/tree_store.c
+++ b/demos/gtk-demo/tree_store.c
@@ -13,6 +13,17 @@
 /*                                                                                                                                   */
 /*************************************************************************************************************************************/
 
+// -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   -   - //
+
+/**************************************************              <>              *****************************************************/
+/*                                                                                                                                   */
+/*  https://developer-old.gnome.org/gtk4/stable/GtkTreeView.html                                                                     */
+/*  GtkTreeViewColumn, GtkTreeSelection, GtkTreeModel, GtkTreeView drag-and-drop, GtkTreeSortable, GtkTreeModelSort, GtkListStore,   */
+/*  GtkTreeStore, GtkCellRenderer, GtkCellEditable, GtkCellRendererPixbuf, GtkCellRendererText, GtkCellRendererToggle                */
+/*                                                                                                                                   */
+/*  https://www.gnu.org/software/guile-gnome/docs/gtk/html/GtkCellRenderer.html                                                      */
+/*                                                                                                                                   */
+/*************************************************************************************************************************************/
 
 
 /* The GtkTreeStore is used to store data in tree form, to be used later on by a GtkTreeView to display it.
@@ -59,7 +70,7 @@ static TreeItem item_name_0[] =
 static TreeItem item_name_1[] =
 {
   { "A", FALSE, TRUE, NULL },
-  { "B", FALSE, FALSE, NULL },
+  { "B", TRUE, FALSE, NULL },
   { "C", FALSE, TRUE, NULL },
   { "D", FALSE, TRUE, NULL },
   { NULL }
@@ -131,70 +142,25 @@ create_model (void)
   return GTK_TREE_MODEL (model);
 }
 
-static void   //  https://www.gnu.org/software/guile-gnome/docs/gtk/html/GtkCellRendererToggle.html
-item_toggled (GtkCellRendererToggle *cell,
-              char                  *path_str,
-              gpointer               data)
-{
-  GtkTreeModel *model = (GtkTreeModel *)data;
-  GtkTreePath *path = gtk_tree_path_new_from_string (path_str);
-  GtkTreeIter iter;
-  gboolean toggle_item;
-
-  int *column;
-
-  column = g_object_get_data (G_OBJECT (cell), "column");
-
-  /* get toggled iter */
-  gtk_tree_model_get_iter (model, &iter, path);
-  gtk_tree_model_get (model, &iter, column, &toggle_item, -1);
-
-  /* do something with the value */
-  toggle_item ^= 1;
-
-  /* set new value */
-  gtk_tree_store_set (GTK_TREE_STORE (model), &iter, column,
-                      toggle_item, -1);
-
-  /* clean up */
-  gtk_tree_path_free (path);
-}
-
 static void
 add_columns (GtkTreeView *treeview)
 {
-  int col_offset;
   GtkCellRenderer *renderer;
-//  GtkTreeViewColumn *column;
-  GtkTreeModel *model = gtk_tree_view_get_model (treeview);
 
   /* column for item_1 names */
   renderer = gtk_cell_renderer_text_new ();
   g_object_set (renderer, "xalign", 0.0, NULL);
 
-  col_offset = gtk_tree_view_insert_column_with_attributes (GTK_TREE_VIEW (treeview), -1, "Col 0", renderer, "text",
-                                                            COLUMN_0, NULL);
-/*  column = */ gtk_tree_view_get_column (GTK_TREE_VIEW (treeview), col_offset - 1);
-//  gtk_tree_view_column_set_clickable (GTK_TREE_VIEW_COLUMN (column), TRUE);
+  gtk_tree_view_insert_column_with_attributes (GTK_TREE_VIEW (treeview), -1,
+      "Col 0", renderer, "text", COLUMN_0, NULL);
 
   /* AA column */
   renderer = gtk_cell_renderer_toggle_new ();
   g_object_set (renderer, "xalign", 0.0, NULL);
   g_object_set_data (G_OBJECT (renderer), "column", (int *)COLUMN_1);
 
-  //  g_signal_connect (renderer, "toggled", G_CALLBACK (item_toggled), model);
-
-  col_offset = gtk_tree_view_insert_column_with_attributes (GTK_TREE_VIEW (treeview), -1, "Col 1", renderer, "active",
-                                                            COLUMN_1, "visible", VISIBLE_COLUMN, "activatable", WORLD_COLUMN, NULL);
-
-/*  column = */ gtk_tree_view_get_column (GTK_TREE_VIEW (treeview), col_offset - 1);
-//  gtk_tree_view_column_set_sizing (GTK_TREE_VIEW_COLUMN (column), GTK_TREE_VIEW_COLUMN_FIXED);
-//  gtk_tree_view_column_set_clickable (GTK_TREE_VIEW_COLUMN (column), TRUE);
-
-/*  column = */ gtk_tree_view_get_column (GTK_TREE_VIEW (treeview), col_offset - 1);
-//  gtk_tree_view_column_set_sizing (GTK_TREE_VIEW_COLUMN (column), GTK_TREE_VIEW_COLUMN_FIXED);
-//  gtk_tree_view_column_set_clickable (GTK_TREE_VIEW_COLUMN (column), TRUE);
-
+  gtk_tree_view_insert_column_with_attributes (GTK_TREE_VIEW (treeview), -1,
+      "Col 1", renderer, "active", COLUMN_1, "visible", VISIBLE_COLUMN, "activatable", WORLD_COLUMN, NULL);
 }
 
 GtkWidget *
@@ -223,8 +189,7 @@ do_tree_store (GtkWidget *do_widget)
       gtk_widget_set_margin_bottom (vbox, 8);
       gtk_window_set_child (GTK_WINDOW (window), vbox);
 
-      gtk_box_append (GTK_BOX (vbox),
-                          gtk_label_new ("Learning GTK trees"));
+      gtk_box_append (GTK_BOX (vbox), gtk_label_new ("Learning GTK trees"));
 
       sw = gtk_scrolled_window_new ();
       gtk_scrolled_window_set_has_frame (GTK_SCROLLED_WINDOW (sw), TRUE);