From 381bdfb32a3f2a5bb5d845a8262b8d9017de7b10 Mon Sep 17 00:00:00 2001
From: Robby Findler <robby@racket-lang.org>
Date: Tue, 25 Feb 2014 10:55:29 -0600
Subject: [PATCH] use private pseudo-random-generator

closes PR 14369
---
 pkgs/htdp-pkgs/htdp-lib/2htdp/private/world.rkt | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/pkgs/htdp-pkgs/htdp-lib/2htdp/private/world.rkt b/pkgs/htdp-pkgs/htdp-lib/2htdp/private/world.rkt
index aa11829145..6514cadb1d 100644
--- a/pkgs/htdp-pkgs/htdp-lib/2htdp/private/world.rkt
+++ b/pkgs/htdp-pkgs/htdp-lib/2htdp/private/world.rkt
@@ -51,6 +51,8 @@
  package-world ;; Package -> World 
  )
 
+(define p-r-g (make-pseudo-random-generator))
+
 (define world%
   (last-mixin
    (clock-mixin
@@ -264,7 +266,10 @@
        (rec    on-receive))
       
       (define drawing #f) ;; Boolean; is a draw callback scheduled?
-      (define (set-draw#!) (set! draw# (random 3)) (set! drawing #f))
+      (define (set-draw#!) 
+        (set! draw# (parameterize ((current-pseudo-random-generator p-r-g))
+                      (random 3)))
+        (set! drawing #f))
       (define draw# 0) 
       (set-draw#!)