wwscroll
wwscroll(selwin, 1);
wwscroll(selwin, -1);
wwscroll(selwin, selwin->ww_w.nr / 2);
wwscroll(selwin, - selwin->ww_w.nr / 2);
wwscroll(selwin, selwin->ww_w.nr);
wwscroll(selwin, - selwin->ww_w.nr);
void wwscroll(struct ww *, int);