+ gpointer group;
+
+ g_return_if_fail (GTK_IS_NOTEBOOK (notebook));
+
+ /* add 1 to get rid of the -1/NULL difference */
+ group = GINT_TO_POINTER (group_id + 1);
+ gtk_notebook_set_group (notebook, group);
+}
+
+/**
+ * gtk_notebook_set_group:
+ * @notebook: a #GtkNotebook
+ * @group_id: a pointer to identify the notebook group, or %NULL to unset it
+ *
+ * Sets a group identificator pointer for @notebook, notebooks sharing
+ * the same group identificator pointer will be able to exchange tabs
+ * via drag and drop. A notebook with a %NULL group identificator will
+ * not be able to exchange tabs with any other notebook.
+ *
+ * Since: 2.12
+ */
+void
+gtk_notebook_set_group (GtkNotebook *notebook,
+ gpointer group)
+{
+ GtkNotebookPrivate *priv;