g_return_val_if_fail (EV_IS_SIDEBAR_PAGE (sidebar_page), FALSE);
g_return_val_if_fail (EV_IS_DOCUMENT (document), FALSE);
iface = EV_SIDEBAR_PAGE_GET_IFACE (sidebar_page);
g_return_val_if_fail (EV_IS_SIDEBAR_PAGE (sidebar_page), FALSE);
g_return_val_if_fail (EV_IS_DOCUMENT (document), FALSE);
iface = EV_SIDEBAR_PAGE_GET_IFACE (sidebar_page);