diff --git a/src/ui/gemgraph.ui b/src/ui/gemgraph.ui
index 22b8dc0..31fe3e1 100644
--- a/src/ui/gemgraph.ui
+++ b/src/ui/gemgraph.ui
@@ -3,7 +3,7 @@
 <interface>
   <!-- interface-name gem-graph.ui -->
   <requires lib="gtk" version="4.6"/>
-  <!--template class="GemGraphClientWindow" parent="GtkApplicationWindow"-->
+  <template class="GemGraphClientWindow" parent="GtkApplicationWindow">
     <property name="default-height">960</property>
     <property name="default-width">1920</property>
     <property name="icon-name">application-x-executable</property>
@@ -244,7 +244,7 @@
         </child>
     </object>
     </child>
-  <!--/template-->
+  </template>
 
   <menu id="main_menu">
     <section>
diff --git a/src/ui/window.c b/src/ui/window.c
index 1535a60..6192a30 100644
--- a/src/ui/window.c
+++ b/src/ui/window.c
@@ -75,6 +75,10 @@ static void gem_graph_client_window_class_init(GemGraphClientWindowClass *klass)
     bytes = g_bytes_new_take(contents, len);
     gtk_widget_class_set_template(GTK_WIDGET_CLASS(klass), bytes);
 
+    //  https://docs.gtk.org/gtk4/class.Widget.html#building-composite-widgets-from-template-xml    TODO   Learn !
+    //  gtk_widget_class_bind_template_callback_full (GtkToggleButton, ui_toggle_sidebar, "clicked"); //  "main_button_sidebar"
+
+
     gtk_widget_class_bind_template_child(widget_class, GemGraphClientWindow, main_titlebar);
     gtk_widget_class_bind_template_child(widget_class, GemGraphClientWindow, main_stack);
     gtk_widget_class_bind_template_child(widget_class, GemGraphClientWindow, side_stack);
@@ -97,6 +101,9 @@ static void gem_graph_client_window_init(GemGraphClientWindow *self)
     window = self;
 }
 
+//  https://docs.gtk.org/gtk4/class.Widget.html#building-composite-widgets-from-template-xml
+static void gtk_widget_class_dispose_template() {}  //  TODO ?
+
 /* -------------------------------------------------------------------------- */
 
 void ui_set_stack(int mode)