7 An Example

(open-graphics)

; nothing appears to happen, but the library is initialized...

(define w (open-viewport "practice" 300 300))

; viewport window appears

((draw-line w) (make-posn 30 30) (make-posn 100 100))

; line appears

(close-viewport w)

; viewport disappears

(close-graphics)

; again, nothing appears to happen, but

; unclosed viewports (if any) would disappear