diff --git a/drracket-core-lib/drracket/drracket.rkt b/drracket-core-lib/drracket/drracket.rkt
index 6f3647f00..58fc4be1c 100644
--- a/drracket-core-lib/drracket/drracket.rkt
+++ b/drracket-core-lib/drracket/drracket.rkt
@@ -30,29 +30,26 @@
                     (define vec (sync evt))
                     (define str (vector-ref vec 1))
                     (when (regexp-match #rx"^cm: *compil(ing|ed)" str)
-                      (display str)
-                      (newline))
+                      (displayln str))
                     (loop))))))
 
 (cond
   [debugging?
    (flprintf "PLTDRDEBUG: loading CM to load/create errortrace zos\n")
-   (let-values ([(zo-compile
-                  make-compilation-manager-load/use-compiled-handler)
-                 (parameterize ([current-namespace (make-base-empty-namespace)]
-                                [use-compiled-file-paths '()])
-                   (values
-                    (dynamic-require 'errortrace/zo-compile 'zo-compile)
-                    (dynamic-require 'compiler/cm 'make-compilation-manager-load/use-compiled-handler)))])
-     (flprintf "PLTDRDEBUG: installing CM to load/create errortrace zos\n")
-     (current-compile zo-compile)
-     (use-compiled-file-paths (list (build-path compiled-dir "errortrace")))
-     (current-load/use-compiled (make-compilation-manager-load/use-compiled-handler))
-     (error-display-handler (dynamic-require 'errortrace/errortrace-lib
-                                             'errortrace-error-display-handler))
-     (when cm-trace?
-       (flprintf "PLTDRDEBUG: enabling CM tracing\n")
-       (run-trace-thread)))]
+   (define-values (zo-compile make-compilation-manager-load/use-compiled-handler)
+     (parameterize ([current-namespace (make-base-empty-namespace)]
+                    [use-compiled-file-paths '()])
+       (values (dynamic-require 'errortrace/zo-compile 'zo-compile)
+               (dynamic-require 'compiler/cm 'make-compilation-manager-load/use-compiled-handler))))
+   (flprintf "PLTDRDEBUG: installing CM to load/create errortrace zos\n")
+   (current-compile zo-compile)
+   (use-compiled-file-paths (list (build-path compiled-dir "errortrace")))
+   (current-load/use-compiled (make-compilation-manager-load/use-compiled-handler))
+   (error-display-handler (dynamic-require 'errortrace/errortrace-lib
+                                           'errortrace-error-display-handler))
+   (when cm-trace?
+     (flprintf "PLTDRDEBUG: enabling CM tracing\n")
+     (run-trace-thread))]
   [install-cm?
    (flprintf "PLTDRCM: loading compilation manager\n")
    (define make-compilation-manager-load/use-compiled-handler
@@ -91,13 +88,12 @@
       (for/list ([x (in-list (find-relevant-directories (list id)))])
         (define proc (get-info/full x))
         (if proc
-            (map (λ (dirs)
-                   (apply build-path
-                          x
-                          (if (list? dirs)
-                              dirs
-                              (list dirs))))
-                 (proc id (λ () '())))
+            (for/list ([dirs (in-list (proc id (λ () '())))])
+              (apply build-path
+                     x
+                     (if (list? dirs)
+                         dirs
+                         (list dirs))))
             '()))))
    
    (define make-compilation-manager-load/use-compiled-handler
diff --git a/drracket-core-lib/drracket/sprof.rkt b/drracket-core-lib/drracket/sprof.rkt
index 9cfe9e625..695dce023 100644
--- a/drracket-core-lib/drracket/sprof.rkt
+++ b/drracket-core-lib/drracket/sprof.rkt
@@ -16,13 +16,11 @@
               (sleep pause-time)
               (define new-traces
                 (map (λ (t) (continuation-mark-set->context (continuation-marks t))) (get-threads)))
-              (for-each (λ (trace)
-                          (for-each (λ (line)
-                                      (hash-set! traces-table
-                                                 line
-                                                 (cons trace (hash-ref traces-table line '()))))
-                                    trace))
-                        new-traces)
+              (for ([trace (in-list new-traces)])
+                (for-each
+                 (λ (line)
+                   (hash-set! traces-table line (cons trace (hash-ref traces-table line '()))))
+                 trace))
               (cond
                 [(zero? i)
                  (update-gui traces-table)
@@ -38,8 +36,8 @@
      (format "~a:~a~a"
              (cond
                [(path? (srcloc-source src))
-                (let-values ([(base name dir?) (split-path (srcloc-source src))])
-                  name)]
+                (define-values (base name dir?) (split-path (srcloc-source src)))
+                name]
                [else (srcloc-source src)])
              (if (srcloc-line src)
                  (format "~a:~a" (srcloc-line src) (srcloc-column src))
@@ -108,14 +106,14 @@
         [(send event button-up? 'left)
          (define admin (get-admin))
          (when admin
-           (let ([dc (send admin get-dc)])
-             (let-values ([(x y) (dc-location-to-editor-location (send event get-x)
-                                                                 (send event get-y))])
-               (let* ([loc (find-position x y)]
-                      [para (position-paragraph loc)])
-                 (set! clicked-srcloc-pr
-                       (and (<= 0 para (last-paragraph)) (car (list-ref gui-display-data para))))
-                 (update-gui-display)))))]
+           (send admin get-dc)
+           (define-values (x y)
+             (dc-location-to-editor-location (send event get-x) (send event get-y)))
+           (define loc (find-position x y))
+           (define para (position-paragraph loc))
+           (set! clicked-srcloc-pr
+                 (and (<= 0 para (last-paragraph)) (car (list-ref gui-display-data para))))
+           (update-gui-display))]
         [else (void)]))
 
     (define/public (set-gui-display-data/refresh traces-table)
@@ -138,12 +136,11 @@
       (set! clear-old-pr void)
       (define denom-ht (make-hasheq))
       (define filtered-gui-display-data
-        (map (λ (pr)
-               (let ([id (car pr)]
-                     [stacks (filter-stacks (cdr pr))])
-                 (for-each (λ (stack) (hash-set! denom-ht stack #t)) stacks)
-                 (cons id stacks)))
-             gui-display-data))
+        (for/list ([pr (in-list gui-display-data)])
+          (define id (car pr))
+          (define stacks (filter-stacks (cdr pr)))
+          (for-each (λ (stack) (hash-set! denom-ht stack #t)) stacks)
+          (cons id stacks)))
       (define denom-count (hash-count denom-ht))
       (let loop ([prs filtered-gui-display-data]
                  [first? #t]
@@ -151,22 +148,22 @@
         (cond
           [(null? prs) (void)]
           [else
-           (let* ([pr (car prs)]
-                  [fn (car pr)]
-                  [count (length (cdr pr))])
-             (cond
-               [(zero? count) (loop (cdr prs) first? i)]
-               [else
-                (unless first?
-                  (insert "\n"))
-                (let ([before (last-position)])
-                  (hash-set! line-to-source i pr)
-                  (insert (format-percentage (/ count denom-count)))
-                  (insert (format " ~a" (format-fn-name fn)))
-                  (let ([after (last-position)])
-                    (when (equal? (car pr) clicked-srcloc-pr)
-                      (set! clear-old-pr (highlight-range before after "NavajoWhite")))))
-                (loop (cdr prs) #f (+ i 1))]))]))
+           (define pr (car prs))
+           (define fn (car pr))
+           (define count (length (cdr pr)))
+           (cond
+             [(zero? count) (loop (cdr prs) first? i)]
+             [else
+              (unless first?
+                (insert "\n"))
+              (let ([before (last-position)])
+                (hash-set! line-to-source i pr)
+                (insert (format-percentage (/ count denom-count)))
+                (insert (format " ~a" (format-fn-name fn)))
+                (let ([after (last-position)])
+                  (when (equal? (car pr) clicked-srcloc-pr)
+                    (set! clear-old-pr (highlight-range before after "NavajoWhite")))))
+              (loop (cdr prs) #f (+ i 1))])]))
       (lock #t)
       (end-edit-sequence)
       (update-info-editor clicked-srcloc-pr)
@@ -373,11 +370,10 @@
           (define/public (get-threads-to-profile)
             (define thds '())
             (let loop ([cust (get-user-custodian)])
-              (for-each (λ (obj)
-                          (cond
-                            [(custodian? obj) (loop obj)]
-                            [(thread? obj) (set! thds (cons obj thds))]))
-                        (custodian-managed-list cust system-custodian)))
+              (for ([obj (in-list (custodian-managed-list cust system-custodian))])
+                (cond
+                  [(custodian? obj) (loop obj)]
+                  [(thread? obj) (set! thds (cons obj thds))])))
             thds)
 
           ;; FIX
diff --git a/drracket-tool-text-lib/drracket/private/syncheck/traversals.rkt b/drracket-tool-text-lib/drracket/private/syncheck/traversals.rkt
index 4a52e9b1f..50e4a81e5 100644
--- a/drracket-tool-text-lib/drracket/private/syncheck/traversals.rkt
+++ b/drracket-tool-text-lib/drracket/private/syncheck/traversals.rkt
@@ -48,76 +48,81 @@
           (λ (sexp [ignored void])
             (parameterize ([current-directory (or user-directory (current-directory))]
                            [current-load-relative-directory user-directory])
-              (let ([is-module? (syntax-case sexp (module)
-                                  [(module . rest) #t]
-                                  [_ #f])])
-                (cond
-                  [is-module?
-                   (let ([phase-to-binders (make-hash)]
-                         [phase-to-varrefs (make-hash)]
-                         [phase-to-varsets (make-hash)]
-                         [phase-to-tops (make-hash)]
-                         [phase-to-requires (make-hash)]
-                         [binding-inits (make-hash)]
-                         [templrefs (make-id-set 0)]
-                         [module-lang-requires (make-hash)]
-                         [requires (make-hash)]
-                         [require-for-syntaxes (make-hash)]
-                         [require-for-templates (make-hash)]
-                         [require-for-labels (make-hash)]
-                         [sub-identifier-binding-directives (make-hash)])
-                     (annotate-basic sexp
-                                     user-namespace user-directory
-                                     phase-to-binders
-                                     phase-to-varrefs
-                                     phase-to-varsets
-                                     phase-to-tops
-                                     binding-inits
-                                     templrefs
-                                     module-lang-requires
-                                     phase-to-requires
-                                     sub-identifier-binding-directives)
-                     (annotate-variables user-namespace
-                                         user-directory
-                                         phase-to-binders
-                                         phase-to-varrefs
-                                         phase-to-varsets
-                                         phase-to-tops
-                                         templrefs
-                                         module-lang-requires
-                                         phase-to-requires
-                                         sub-identifier-binding-directives)
-                     (annotate-contracts sexp
-                                         (hash-ref phase-to-binders 0 (λ () (make-id-set 0)))
-                                         (hash-ref binding-inits 0 (λ () (make-id-set 0)))
-                                         binder+mods-binder)
-                     (when print-extra-info?
-                       (print-extra-info (list (list 'phase-to-binders phase-to-binders)
-                                               (list 'phase-to-varrefs phase-to-varrefs)
-                                               (list 'phase-to-varsets phase-to-varsets)
-                                               (list 'phase-to-tops phase-to-tops)
-                                               (list 'phase-to-requires phase-to-requires)
-                                               (list 'binding-inits binding-inits)
-                                               (list 'templrefs templrefs)
-                                               (list 'module-lang-requires module-lang-requires)
-                                               (list 'requires requires)
-                                               (list 'require-for-syntaxes require-for-syntaxes)
-                                               (list 'require-for-templates require-for-templates)
-                                               (list 'require-for-labels require-for-labels)
-                                               (list 'sub-identifier-binding-directives
-                                                     sub-identifier-binding-directives)))))]
-                  [else
+              (define is-module?
+                (syntax-case sexp (module)
+                  [(module . rest
+                     )
+                   #t]
+                  [_ #f]))
+              (cond
+                [is-module?
+                 (let ([phase-to-binders (make-hash)]
+                       [phase-to-varrefs (make-hash)]
+                       [phase-to-varsets (make-hash)]
+                       [phase-to-tops (make-hash)]
+                       [phase-to-requires (make-hash)]
+                       [binding-inits (make-hash)]
+                       [templrefs (make-id-set 0)]
+                       [module-lang-requires (make-hash)]
+                       [requires (make-hash)]
+                       [require-for-syntaxes (make-hash)]
+                       [require-for-templates (make-hash)]
+                       [require-for-labels (make-hash)]
+                       [sub-identifier-binding-directives (make-hash)])
                    (annotate-basic sexp
-                                   user-namespace user-directory
-                                   tl-phase-to-binders
-                                   tl-phase-to-varrefs
-                                   tl-phase-to-varsets
-                                   tl-phase-to-tops
-                                   tl-binding-inits
-                                   tl-templrefs
-                                   tl-module-lang-requires
-                                   tl-phase-to-requires
-                                   tl-sub-identifier-binding-directives)]))))]
+                                   user-namespace
+                                   user-directory
+                                   phase-to-binders
+                                   phase-to-varrefs
+                                   phase-to-varsets
+                                   phase-to-tops
+                                   binding-inits
+                                   templrefs
+                                   module-lang-requires
+                                   phase-to-requires
+                                   sub-identifier-binding-directives)
+                   (annotate-variables user-namespace
+                                       user-directory
+                                       phase-to-binders
+                                       phase-to-varrefs
+                                       phase-to-varsets
+                                       phase-to-tops
+                                       templrefs
+                                       module-lang-requires
+                                       phase-to-requires
+                                       sub-identifier-binding-directives)
+                   (annotate-contracts sexp
+                                       (hash-ref phase-to-binders 0 (λ () (make-id-set 0)))
+                                       (hash-ref binding-inits 0 (λ () (make-id-set 0)))
+                                       binder+mods-binder)
+                   (when print-extra-info?
+                     (print-extra-info (list (list 'phase-to-binders phase-to-binders)
+                                             (list 'phase-to-varrefs phase-to-varrefs)
+                                             (list 'phase-to-varsets phase-to-varsets)
+                                             (list 'phase-to-tops phase-to-tops)
+                                             (list 'phase-to-requires phase-to-requires)
+                                             (list 'binding-inits binding-inits)
+                                             (list 'templrefs templrefs)
+                                             (list 'module-lang-requires module-lang-requires)
+                                             (list 'requires requires)
+                                             (list 'require-for-syntaxes require-for-syntaxes)
+                                             (list 'require-for-templates require-for-templates)
+                                             (list 'require-for-labels require-for-labels)
+                                             (list 'sub-identifier-binding-directives
+                                                   sub-identifier-binding-directives)))))]
+                [else
+                 (annotate-basic sexp
+                                 user-namespace
+                                 user-directory
+                                 tl-phase-to-binders
+                                 tl-phase-to-varrefs
+                                 tl-phase-to-varsets
+                                 tl-phase-to-tops
+                                 tl-binding-inits
+                                 tl-templrefs
+                                 tl-module-lang-requires
+                                 tl-phase-to-requires
+                                 tl-sub-identifier-binding-directives)])))]
          [expansion-completed
           (λ ()
             (parameterize ([current-directory (or user-directory (current-directory))]
diff --git a/drracket/gui-debugger/debug-tool.rkt b/drracket/gui-debugger/debug-tool.rkt
index ce8e80c38..837dded50 100644
--- a/drracket/gui-debugger/debug-tool.rkt
+++ b/drracket/gui-debugger/debug-tool.rkt
@@ -191,18 +191,16 @@
             (begin-edit-sequence)
             (define breakpoints (send (get-tab) get-breakpoints))
             (define shifts empty)
-            (hash-for-each
-             breakpoints
-             (lambda (pos status)
-               (cond
-                 ; deletion after breakpoint: no effect
-                 [(<= pos start)]
-                 ; deletion of breakpoint: remove from table
-                 [(and (< start pos) (<= pos (+ start len))) (hash-remove! breakpoints pos)]
-                 ; deletion before breakpoint: shift breakpoint
-                 [(> pos (+ start len))
-                  (hash-remove! breakpoints pos)
-                  (set! shifts (cons (cons (- pos len) status) shifts))])))
+            (for ([(pos status) (in-hash breakpoints)])
+              (cond
+                ; deletion after breakpoint: no effect
+                [(<= pos start)]
+                ; deletion of breakpoint: remove from table
+                [(and (< start pos) (<= pos (+ start len))) (hash-remove! breakpoints pos)]
+                ; deletion before breakpoint: shift breakpoint
+                [(> pos (+ start len))
+                 (hash-remove! breakpoints pos)
+                 (set! shifts (cons (cons (- pos len) status) shifts))]))
             (for-each (lambda (p) (hash-set! breakpoints (car p) (cdr p))) shifts))
           (inner (void) on-delete start len))
         
@@ -219,13 +217,12 @@
             (begin-edit-sequence)
             (define breakpoints (send (get-tab) get-breakpoints))
             (define shifts empty)
-            (hash-for-each breakpoints
-                           (lambda (pos status)
-                             (when (< start pos)
-                               ;; text inserted before this breakpoint, so shift
-                               ;; the breakpoint forward by <len> positions
-                               (hash-remove! breakpoints pos)
-                               (set! shifts (cons (cons (+ pos len) status) shifts)))))
+            (for ([(pos status) (in-hash breakpoints)])
+              (when (< start pos)
+                ;; text inserted before this breakpoint, so shift
+                ;; the breakpoint forward by <len> positions
+                (hash-remove! breakpoints pos)
+                (set! shifts (cons (cons (+ pos len) status) shifts))))
             ;; update the breakpoint locations
             (for-each (lambda (p) (hash-set! breakpoints (car p) (cdr p))) shifts)))
         
@@ -489,28 +486,26 @@
           (when (and (send (get-tab) debug?) (not before))
             ;; render breakpoints
             (let ([breakpoints (send (get-tab) get-breakpoints)])
-              (hash-for-each
-               breakpoints
-               (lambda (pos enabled?)
-                 (when (and (>= pos 0) (or enabled? (and mouse-over-pos (= mouse-over-pos pos))))
-                   (define-values (xl yl xr yr) (find-char-box this pos))
-                   (define diameter (- xr xl))
-                   (define yoff (/ (- yr yl diameter) 2))
-                   (define op (send dc get-pen))
-                   (define ob (send dc get-brush))
-                   (case enabled?
-                     [(#t)
-                      (send dc set-pen bp-pen)
-                      (send dc set-brush bp-brush)]
-                     [(#f)
-                      (send dc set-pen bp-mo-pen)
-                      (send dc set-brush bp-mo-brush)]
-                     [else
-                      (send dc set-pen bp-tmp-pen)
-                      (send dc set-brush bp-tmp-brush)])
-                   (send dc draw-ellipse (+ xl dx) (+ yl dy yoff) diameter diameter)
-                   (send dc set-pen op)
-                   (send dc set-brush ob)))))
+              (for ([(pos enabled?) (in-hash breakpoints)])
+                (when (and (>= pos 0) (or enabled? (and mouse-over-pos (= mouse-over-pos pos))))
+                  (define-values (xl yl xr yr) (find-char-box this pos))
+                  (define diameter (- xr xl))
+                  (define yoff (/ (- yr yl diameter) 2))
+                  (define op (send dc get-pen))
+                  (define ob (send dc get-brush))
+                  (case enabled?
+                    [(#t)
+                     (send dc set-pen bp-pen)
+                     (send dc set-brush bp-brush)]
+                    [(#f)
+                     (send dc set-pen bp-mo-pen)
+                     (send dc set-brush bp-mo-brush)]
+                    [else
+                     (send dc set-pen bp-tmp-pen)
+                     (send dc set-brush bp-tmp-brush)])
+                  (send dc draw-ellipse (+ xl dx) (+ yl dy yoff) diameter diameter)
+                  (send dc set-pen op)
+                  (send dc set-brush ob))))
             ;; mark the boundaries of the current stack frame
             ;; unless we're at the end of the expression and looking at the top frame,
             ;; in which case just mark the current location
@@ -804,11 +799,11 @@
                    ; break-after
                    (case-lambda
                      [(top-mark ccm val)
-                      (let* ([debug-marks (continuation-mark-set->list ccm debug-key)])
-                        (car (send (get-tab) suspend
-                                   oeh
-                                   (cons top-mark debug-marks)
-                                   (list 'exit-break val))))]
+                      (define debug-marks (continuation-mark-set->list ccm debug-key))
+                      (car (send (get-tab) suspend
+                                 oeh
+                                 (cons top-mark debug-marks)
+                                 (list 'exit-break val)))]
                      [(top-mark ccm . vals)
                       (define debug-marks (continuation-mark-set->list ccm debug-key))
                       (apply values
@@ -818,15 +813,16 @@
                                    (cons 'exit-break vals)))])))
                  (uncaught-exception-handler
                   (lambda (exn)
-                    (if (and (exn:break? exn) (send (get-tab) suspend-on-break?))
-                        (let ([marks (exn-continuation-marks exn)]
-                              [cont (exn:break-continuation exn)])
-                          (send (get-tab) suspend
-                                oeh
-                                (continuation-mark-set->list marks debug-key)
-                                'break)
-                          (cont))
-                        (oeh exn)))))))))))
+                    (cond
+                      [(and (exn:break? exn) (send (get-tab) suspend-on-break?))
+                       (define marks (exn-continuation-marks exn))
+                       (define cont (exn:break-continuation exn))
+                       (send (get-tab) suspend
+                             oeh
+                             (continuation-mark-set->list marks debug-key)
+                             'break)
+                       (cont)]
+                      [else (oeh exn)]))))))))))
     
     (define (debug-tab-mixin super%)
       (class super%
@@ -1237,37 +1233,37 @@
           (send variables-text end-edit-sequence))
         
         (define/public (register-stack-frames frames already-stopped?)
-          (let* ([trimmed-exprs
-                  (map (lambda (frame)
-                         (let ([expr (mark-source frame)])
-                           (cond
-                             ; should succeed unless the user closes a secondary tab during debugging
-                             [(and expr (filename->defs (syntax-source expr)))
-                              => (lambda (defs)
-                                   (trim-expr-str
-                                    (if (syntax-position expr)
-                                        (send defs get-text
-                                              (sub1 (syntax-position expr))
-                                              (+ -1 (syntax-position expr) (syntax-span expr)))
-                                        "??")
-                                    15))]
-                             ["??"])))
-                       frames)]
-                 [trimmed-lengths (map add1 (map string-length trimmed-exprs))]
-                 [positions (foldl + 0 trimmed-lengths)])
-            (send stack-frames begin-edit-sequence)
-            (send stack-frames lock #f)
-            (unless already-stopped?
-              (send stack-frames delete 0 (send stack-frames last-position))
-              (for-each (lambda (trimmed-expr)
-                          (send stack-frames insert (format "~a\n" trimmed-expr)))
-                        trimmed-exprs))
-            (send stack-frames change-style normal-sd 0 (send stack-frames last-position))
-            (send stack-frames change-style bold-sd
-                  (send stack-frames paragraph-start-position (send (get-current-tab) get-frame-num))
-                  (send stack-frames paragraph-end-position (send (get-current-tab) get-frame-num)))
-            (send stack-frames lock #t)
-            (send stack-frames end-edit-sequence)))
+          (define trimmed-exprs
+            (map (lambda (frame)
+                   (let ([expr (mark-source frame)])
+                     (cond
+                       ; should succeed unless the user closes a secondary tab during debugging
+                       [(and expr (filename->defs (syntax-source expr)))
+                        =>
+                        (lambda (defs)
+                          (trim-expr-str (if (syntax-position expr)
+                                             (send defs get-text
+                                                   (sub1 (syntax-position expr))
+                                                   (+ -1 (syntax-position expr) (syntax-span expr)))
+                                             "??")
+                                         15))]
+                       ["??"])))
+                 frames))
+          (define trimmed-lengths (map add1 (map string-length trimmed-exprs)))
+          (foldl + 0 trimmed-lengths)
+          (send stack-frames begin-edit-sequence)
+          (send stack-frames lock #f)
+          (unless already-stopped?
+            (send stack-frames delete 0 (send stack-frames last-position))
+            (for-each (lambda (trimmed-expr) (send stack-frames insert (format "~a\n" trimmed-expr)))
+                      trimmed-exprs))
+          (send stack-frames change-style normal-sd 0 (send stack-frames last-position))
+          (send stack-frames change-style
+                bold-sd
+                (send stack-frames paragraph-start-position (send (get-current-tab) get-frame-num))
+                (send stack-frames paragraph-end-position (send (get-current-tab) get-frame-num)))
+          (send stack-frames lock #t)
+          (send stack-frames end-edit-sequence))
         
         (define/public (clear-stack-frames/vars)
           (send stack-frames begin-edit-sequence)
@@ -1551,29 +1547,35 @@
         
         (define/augment (on-tab-change old new)
           (check-current-language-for-debugger)
-          (if (send new debug?)
-              (let ([status (send new get-break-status)])
-                (if status
-                    (send new suspend-gui (send new get-stack-frames) status #f #t)
-                    (send new resume-gui))
-                (show-debug))
-              (hide-debug))
+          (cond
+            [(send new debug?)
+             (define status (send new get-break-status))
+             (if status
+                 (send new suspend-gui (send new get-stack-frames) status #f #t)
+                 (send new resume-gui))
+             (show-debug)]
+            [else (hide-debug)])
           (inner (void) on-tab-change old new))
         
         (define/public (check-current-language-for-debugger)
-          (let* ([settings (send (get-definitions-text) get-next-settings)]
-                 [lang (drscheme:language-configuration:language-settings-language settings)]
-                 [visible? (and (send lang capability-value 'gui-debugger:debug-button)
-                                (not (is-a? lang drscheme:module-language:module-language<%>)) ;; the opt-out button handles this language
-                                (not (debugger-does-not-work-for?
-                                      (extract-language-level settings))))])
-            (define debug-parent (send debug-button get-parent))
-            (define debug-button-currently-visible? (member debug-button (send debug-parent get-children)))
-            (if visible?
-                (unless debug-button-currently-visible?
-                  (send debug-parent add-child debug-button))
-                (when debug-button-currently-visible?
-                  (send debug-parent delete-child debug-button)))))
+          (define settings (send (get-definitions-text) get-next-settings))
+          (define lang (drscheme:language-configuration:language-settings-language settings))
+          (define visible?
+            (and
+             (send lang capability-value 'gui-debugger:debug-button)
+             (not
+              (is-a?
+               lang
+               drscheme:module-language:module-language<%>)) ;; the opt-out button handles this language
+             (not (debugger-does-not-work-for? (extract-language-level settings)))))
+          (define debug-parent (send debug-button get-parent))
+          (define debug-button-currently-visible?
+            (member debug-button (send debug-parent get-children)))
+          (if visible?
+              (unless debug-button-currently-visible?
+                (send debug-parent add-child debug-button))
+              (when debug-button-currently-visible?
+                (send debug-parent delete-child debug-button))))
         
         (send (get-button-panel) change-children
               (lambda (children)
@@ -1582,7 +1584,7 @@
         
         ; hide debug button if it's not supported for the initial language:
         (check-current-language-for-debugger)))
-    (drscheme:language:register-capability 'gui-debugger:debug-button (flat-contract boolean?) #t)
+    (drscheme:language:register-capability 'gui-debugger:debug-button boolean? #t)
     (drscheme:get/extend:extend-definitions-text debug-definitions-text-mixin)
     (drscheme:get/extend:extend-interactions-text debug-interactions-text-mixin)
     (drscheme:get/extend:extend-unit-frame debug-unit-frame-mixin)
diff --git a/drracket/version/tool.rkt b/drracket/version/tool.rkt
index 81aca6f9e..b543f5b96 100644
--- a/drracket/version/tool.rkt
+++ b/drracket/version/tool.rkt
@@ -30,9 +30,11 @@
   ;; wait until the definitions are instantiated, return top-level window
   (define (wait-for-definitions)
     (define ws (get-top-level-windows))
-    (if (null? ws)
-      (begin (sleep 1) (wait-for-definitions))
-      (car ws)))
+    (cond
+      [(null? ws)
+       (sleep 1)
+       (wait-for-definitions)]
+      [else (car ws)]))
   #| ;; Cute code, but may resize the window if too much space, and people
      ;; didn't like this way of asking if you want update checks.
   ;; show a message and a disable button