diff --git a/universe.rkt b/universe.rkt
index 47be377..4335130 100644
--- a/universe.rkt
+++ b/universe.rkt
@@ -4,7 +4,7 @@
 (require racket/match)
 (require racket/class)
 (require racket/async-channel)
-(require racket/gui/base)
+(require (except-in racket/gui/base yield))
 (require 2htdp/image)
 (require "os2.rkt")
 
@@ -25,7 +25,7 @@
   (wrap-evt (alarm-evt msecs) (lambda (_) (current-inexact-milliseconds))))
 
 (define wild-sub (topic-subscriber (wild)))
-(define (broadcast message) (send-message (topic-publisher 'universe) message))
+(define (broadcast message) (send-message message))
 
 (define (replace-world w1 w2)
   (cond
@@ -44,43 +44,41 @@
      (on-tick tick-expr rate-expr 0))
     ((_ tick-expr rate-expr limit-expr)
      (list
-      (role wild-sub
+      (role 'on-tick wild-sub
 	#:state w
-	#:id id
 	['tick (replace-world w (tick-expr w))])
       (spawn (transition (ticker-state 0 rate-expr limit-expr)
-	       (role wild-sub
+	       (role 'tick-stopper wild-sub
 		 #:state ts
 		 ['stop (transition ts (kill))])
 	       (let loop ((next-alarm-time 0))
-		 (role (topic-subscriber (time-evt next-alarm-time))
+		 (role 'tick-sequence (topic-subscriber (cons (time-evt next-alarm-time) (wild)))
 		   #:state (and ts (ticker-state counter interval limit))
-		   #:id id
-		   [now
+		   [(cons _ now)
 		    (if (and (positive? limit) (>= counter limit))
 			(transition ts (kill))
 			(transition (ticker-state (+ counter 1) interval limit)
-			  (delete-role id)
+			  (delete-role 'tick-sequence)
 			  (loop (+ now (* 1000 interval)))
 			  (broadcast 'tick)))]))))))))
 
 (define-syntax-rule (on-key key-expr)
-  (role wild-sub
+  (role 'on-key wild-sub
     #:state w
     [`(key-down ,kev) (replace-world w (key-expr w kev))]))
 
 (define-syntax-rule (on-release release-expr)
-  (role wild-sub
+  (role 'on-release wild-sub
     #:state w
     [`(key-up ,kev) (replace-world w (release-expr w kev))]))
 
 (define-syntax-rule (on-mouse mouse-expr)
-  (role wild-sub
+  (role 'on-mouse wild-sub
     #:state w
     [`(mouse ,x ,y ,mev) (replace-world w (mouse-expr w x y mev))]))
 
 (define-syntax-rule (stop-when last-world?)
-  (role wild-sub
+  (role 'stop-when wild-sub
     #:state w
     [`(new-state ,_) (if (last-world? w)
 			 (replace-world w (stop-with w))
@@ -89,19 +87,22 @@
 (define-syntax-rule (on-draw render-expr) (to-draw render-expr))
 
 (define-syntax-rule (to-draw render-expr)
-  (role wild-sub
+  (role 'to-draw wild-sub
     #:state w
     [`(new-state ,_) (transition w (broadcast `(render ,(render-expr w))))]))
 
 (define (ui-actions c:ui->world c:world->ui)
   (list 
-   (role (topic-subscriber c:ui->world) #:state w)
-   (role wild-sub
+   (role 'ui-actions (topic-subscriber (cons c:ui->world (wild)))
+     #:state w
+     [(cons _ e)
+      (transition w (send-message e))])
+   (role 'ui-stopper wild-sub
      #:state w
      ['stop
       (async-channel-put c:world->ui 'stop)
       (transition w (kill))])
-   (role wild-sub
+   (role 'ui-renderer wild-sub
      #:state w
      [`(render ,scene)
       (async-channel-put c:world->ui `(render ,scene))
@@ -173,7 +174,7 @@
 	      (loop))))
 
   (define (error-listener topic)
-    (role topic
+    (role 'error-listener topic
       #:state w
       #:topic flow
       #:reason reason