/*! Tries to register on the screen given by @sc. If it succeeds, it fills
in @sc and returns TRUE, otherwise it returns FALSE.
*/
-gboolean screen_register(d_screen_t *sc);
+gboolean screen_register(struct d_display *dpy, int num, d_screen_t *sc);
void screen_add_window(d_screen_t *sc, xcb_window_t wid);
void screen_remove_window(d_screen_t *sc, struct d_window *w);