Comment 4 for bug 781432

this is what nvidia-settings does on treeview selection change:
    /*
     * remove the existing widget from the page viewer, if anything is
     * presently there
     */

    if (ctk_window->page) {
        gtk_container_remove(GTK_CONTAINER(ctk_window->page_viewer),
                             ctk_window->page);
        ctk_window->page = NULL;
    }

and this happens afterwards:
    /* Pack the new widget */

    if (widget) {
        ctk_window->page = widget;
        gtk_box_pack_start(GTK_BOX(ctk_window->page_viewer), widget,
                           TRUE, TRUE, 2);
    }

No unmap event is received