-        g_signal_connect (m_widget, "switch_page",
-                          G_CALLBACK (gtk_notebook_page_changing_callback), this);
-
-        g_signal_connect_after (m_widget, "switch_page",
-                      G_CALLBACK (gtk_notebook_page_changed_callback), this);
+        g_signal_handlers_unblock_by_func(m_widget,
+            (gpointer)gtk_notebook_page_changed_callback, this);