-void gtk_gs_center_page(GtkGS * gs);
-void gtk_gs_scroll(GtkGS * gs, gint, gint);
-gboolean gtk_gs_scroll_step(GtkGS * gs, GtkScrollType direction,
- gboolean dowrap);
-gboolean gtk_gs_scroll_to_edge(GtkGS * gs, GtkPositionType vertical,
- GtkPositionType horizontal);