vtowin
struct ww *vtowin(struct value *, struct ww *);
if ((w = vtowin(a++, selwin)) == NULL)
if ((w = vtowin(a, (struct ww *)0)) == NULL)
if ((w = vtowin(a, selwin)) == NULL)
if ((w = vtowin(a, selwin)) == NULL)
if ((w = vtowin(a++, selwin)) == NULL)
if ((w = vtowin(a, (struct ww *)0)) != NULL)
if ((w = vtowin(a++, selwin)) == NULL)