diff --git a/collects/drracket/private/module-language-tools.rkt b/collects/drracket/private/module-language-tools.rkt
index 3ca2998d8f..27e0fa39c8 100644
--- a/collects/drracket/private/module-language-tools.rkt
+++ b/collects/drracket/private/module-language-tools.rkt
@@ -83,9 +83,10 @@
           (sort-toolbar-buttons-panel)))
       (super-new)
       (inherit get-button-panel)
-      (set! toolbar-button-panel (new horizontal-panel% 
+      (set! toolbar-button-panel (new panel:horizontal-discrete-sizes% 
                                       [parent (get-button-panel)]
-                                      [stretchable-width #f]))
+                                      [alignment '(right center)]
+                                      [stretchable-width #t]))
       (after-initialized)
       (set! after-initialized void)
       
diff --git a/collects/drracket/private/unit.rkt b/collects/drracket/private/unit.rkt
index f174befeca..eaea4c25e8 100644
--- a/collects/drracket/private/unit.rkt
+++ b/collects/drracket/private/unit.rkt
@@ -55,8 +55,6 @@ module browser threading seems wrong.
 (define show-planet-paths (string-constant module-browser-show-planet-paths/short))
 (define refresh (string-constant module-browser-refresh))
 
-(define define-button-long-label "(define ...)")
-
 (define oprintf
   (let ([op (current-output-port)])
     (λ args
@@ -1896,7 +1894,8 @@ module browser threading seems wrong.
           (let loop ([obj button-panel])
             (when (is-a? obj area-container<%>)
               (when (or (is-a? obj vertical-panel%)
-                        (is-a? obj horizontal-panel%))
+                        (is-a? obj horizontal-panel%)
+                        (is-a? obj panel:discrete-sizes<%>))
                 (unless (equal? (send obj get-orientation) (not vertical?))
                   (send obj set-orientation (not vertical?))))
               (for-each loop (send obj get-children))))
@@ -4372,7 +4371,10 @@ module browser threading seems wrong.
       [define teachpack-items null]
       [define break-button (void)]
       [define execute-button (void)]
-      [define button-panel (new horizontal-panel% [parent top-panel] [spacing 2])]
+      [define button-panel (new panel:horizontal-discrete-sizes% 
+                                [parent top-panel]
+                                [stretchable-width #t]
+                                [alignment '(right center)])]
       (define/public (get-execute-button) execute-button)
       (define/public (get-break-button) break-button)
       (define/public (get-button-panel) button-panel)
@@ -4454,14 +4456,9 @@ module browser threading seems wrong.
                  [label (string-constant break-button-label)]))
       (register-toolbar-button break-button #:number 101)
       
-      (send button-panel stretchable-height #f)
-      (send button-panel stretchable-width #f) 
-      
       (send top-panel change-children
             (λ (l)
-              (list name-panel save-button
-                    (make-object vertical-panel% top-panel) ;; spacer
-                    button-panel)))
+              (list name-panel save-button button-panel)))
       
       (send top-panel stretchable-height #f)
       (inherit get-label)
@@ -4816,7 +4813,7 @@ module browser threading seems wrong.
                   (string-constant no-full-name-since-not-saved)])
       
       (inherit set-allow-shrinking)
-      (set-allow-shrinking 100)))
+      (set-allow-shrinking 50)))
   
   
   
diff --git a/collects/framework/private/frame.rkt b/collects/framework/private/frame.rkt
index 5eca14274b..0b7c6b9683 100644
--- a/collects/framework/private/frame.rkt
+++ b/collects/framework/private/frame.rkt
@@ -1124,7 +1124,7 @@
                                  [extra-menu-items (λ (menu) (add-line-number-menu-items menu))]))
     (define position-canvas (new position-canvas% 
                                  [parent position-parent] 
-                                 [init-width "000:00-000:00"]))
+                                 [init-width "1:1"]))
     (define/private (change-position-edit-contents str)
       (send position-canvas set-str str))
     
diff --git a/collects/framework/private/panel.rkt b/collects/framework/private/panel.rkt
index ca48f1cfb4..5e71738020 100644
--- a/collects/framework/private/panel.rkt
+++ b/collects/framework/private/panel.rkt
@@ -1,10 +1,14 @@
-#lang racket/unit
+#lang racket/base
 
-  (require racket/class
-           racket/list
-           "sig.rkt"
-           mred/mred-sig)
+(require racket/class
+         racket/list
+         racket/unit
+         "sig.rkt"
+         mred/mred-sig
+         mrlib/switchable-button)
+(provide panel@)
 
+(define-unit panel@
   (import [prefix icon: framework:icon^]
           mred^)
   (export framework:panel^)
@@ -634,6 +638,261 @@
     ;; canvas (widget -> editor) -> editor
     (define/public (split-vertical canvas maker)
       (do-split canvas maker (generic splitter-private<%> self-vertical?)
-                vertical-panel% (generic splitter<%> split-vertical)))
+                vertical-panel% (generic splitter<%> split-vertical)))))
 
-    ))
+    
+  (define discrete-child<%> 
+    (interface ()
+      get-discrete-widths
+      get-discrete-heights))
+  
+  (define discrete-sizes<%> (interface ((class->interface panel%))
+                              get-orientation
+                              set-orientation))
+  
+  (define (discrete-get-widths c)
+    (cond
+      [(is-a? c switchable-button%) 
+       (list (send c get-large-width)
+             (send c get-small-width))]
+      [(is-a? c discrete-sizes<%>)
+       (send c get-discrete-widths)]
+      [else
+       #f]))
+  
+  (define (discrete-get-heights c)
+    (cond
+      [(is-a? c discrete-sizes<%>)
+       (send c get-discrete-heights)]
+      [else
+       #f]))
+  
+  (define discrete-sizes-mixin
+    (mixin ((class->interface panel%)) (discrete-sizes<%> discrete-child<%>)
+      (inherit get-children spacing get-alignment border container-flow-modified
+               get-size get-client-size)
+      (define horizontal? #t)
+      (define/public (get-orientation) horizontal?)
+      (define/public (set-orientation h?)
+        (unless (equal? horizontal? h?)
+          (set! horizontal? h?)
+          (container-flow-modified)))
+      
+      (define/public (get-discrete-widths)
+        (cond
+          [horizontal?
+           (define ws 
+             (for/list ([c (in-list (get-children))])
+               (discrete-get-widths c)))
+           (and (andmap values ws)
+                (remove-duplicates
+                 (map
+                  (λ (x) (apply + x))
+                  (candidate-sizes ws))))]
+          [else #f]))
+      
+      (define/public (get-discrete-heights)
+        (cond
+          [horizontal? #f]
+          [else
+           (define hs 
+             (for/list ([c (in-list (get-children))])
+               (discrete-get-heights c)))
+           (and (andmap values hs)
+                (remove-duplicates
+                 (map
+                  (λ (x) (apply + x))
+                  (candidate-sizes hs))))]))
+      
+      (define/override (container-size infos)
+        (define the-spacing (spacing))
+        (define the-border (spacing))
+        (define-values (total-min-w total-min-h)
+          (for/fold ([w 0] [h 0])
+            ([info (in-list infos)]
+             [n (in-naturals)])
+            (define-values (min-w min-h h-stretch? v-stretch?)
+              (apply values info))
+            (define this-spacing (if (zero? n) 0 the-spacing))
+            (cond
+              [horizontal?
+               (values (+ w this-spacing min-w)
+                       (max h min-h))]
+              [else
+               (values (max w min-w)
+                       (+ h this-spacing min-h))])))
+        (define-values (sw sh) (get-size))
+        (define-values (cw ch) (get-client-size))
+        (values (+ total-min-w the-border the-border
+                   (- sw cw))
+                (+ total-min-h the-border the-border
+                   (- sh ch))))
+      
+      (define/override (place-children infos w h)
+        (define the-spacing (spacing))
+        (define the-border (border))
+        (define-values (halign valign) (get-alignment))
+        (define children (get-children))
+        (define all-sizess
+          (candidate-sizes
+           (for/list ([c (in-list children)]
+                      [info (in-list infos)]
+                      #:unless (if horizontal?
+                                   (and (not (discrete-get-widths c))
+                                        (list-ref info 2))
+                                   (and (not (discrete-get-heights c))
+                                        (list-ref info 3))))
+             (if horizontal?
+                 (or (discrete-get-widths c)
+                     (list (list-ref info 0)))
+                 (or (discrete-get-heights c)
+                     (list (list-ref info 1)))))))
+        (define fitting-sizes
+          (for/or ([sizes (in-list all-sizess)])
+            (and (<= (apply + sizes) 
+                     (- (if horizontal? w h)
+                        (* 2 the-border)))
+                 sizes)))
+        (define fixed-size (apply + fitting-sizes))
+        (define number-stretchable
+          (for/sum ([info (in-list infos)]
+                    [c children])
+            (if (if horizontal?
+                    (and (not (discrete-get-widths c))
+                         (list-ref info 2))
+                    (and (not (discrete-get-heights c))
+                         (list-ref info 3)))
+                1
+                0)))
+        (define initial-position
+          (+ the-border
+             (if (zero? number-stretchable)
+                 (if horizontal?
+                     (case halign
+                       [(right) (- w fixed-size)]
+                       [(center) (round (/ (- w fixed-size) 2))]
+                       [(left) 0])
+                     (case valign
+                       [(bottom) (- h fixed-size)]
+                       [(center) (round (/ (- h fixed-size) 2))]
+                       [(top) 0]))
+                 0)))
+        (define-values (stretchable-size stretchable-leftover)
+          (if (zero? number-stretchable)
+              (values 0 0)
+              (let ([total 
+                     (- (if horizontal?
+                            w
+                            h)
+                        fixed-size)])
+                (values (quotient total number-stretchable)
+                        (modulo total number-stretchable)))))
+        (define (take-one) 
+          (cond
+            [(zero? stretchable-leftover)
+             0]
+            [else
+             (set! stretchable-leftover (- stretchable-leftover 1))
+             1]))
+        (let loop ([infos infos]
+                   [children children]
+                   [spot initial-position])
+          (cond
+            [(null? infos) null]
+            [else
+             (define-values (min-w min-h h-stretch? v-stretch?)
+               (apply values (car infos)))
+             (define discrete-child? (if horizontal?
+                                         (discrete-get-widths (car children))
+                                         (discrete-get-heights (car children))))
+             (define this-one
+               (cond
+                 [(and horizontal? h-stretch? (not discrete-child?))
+                  (list spot
+                        (round (- (/ h 2) (/ min-h 2)))
+                        (+ stretchable-size (take-one))
+                        min-h)]
+                 [(and (not horizontal?) v-stretch? (not discrete-child?))
+                  (list (round (- (/ w 2) (/ min-w 2)))
+                        spot
+                        min-w
+                        (+ stretchable-size (take-one)))]
+                 [horizontal?
+                  (define size (car fitting-sizes))
+                  (set! fitting-sizes (cdr fitting-sizes))
+                  (list spot 
+                        (round (- (/ h 2) (/ min-h 2)))
+                        size
+                        min-h)]
+                 [else
+                  (define size (car fitting-sizes))
+                  (set! fitting-sizes (cdr fitting-sizes))
+                  (list (round (- (/ w 2) (/ min-w 2)))
+                        spot
+                        min-w
+                        size)]))
+             (cons this-one (loop (cdr infos)
+                                  (cdr children)
+                                  (+ spot
+                                     (if horizontal? 
+                                         (list-ref this-one 2)
+                                         (list-ref this-one 3)))))])))
+      
+      (super-new)))
+  
+  (define horizontal-discrete-sizes%
+    ;; extra wrapper to get the name right
+    (class (discrete-sizes-mixin panel%)
+      (super-new)))
+  (define vertical-discrete-sizes%
+    (class (discrete-sizes-mixin panel%)
+      (super-new)
+      (inherit set-orientation)
+      (set-orientation #f))))
+
+
+;; candidate-sizes : (listof (listof number)) -> (listof (listof number))
+;; in the input, the outer list corresponds to the children for a panel,
+;; and each inner list are the sizes that the children can take on.
+;; This function returns each possible configuration of sizes, starting
+;; with the largest for each and then shrinking each child one size
+;; at a time, starting from the earlier children in the list.
+;; Note that this will not try all combinations of sizes; once a child
+;; has been shrunk one size, larger sizes for that child will not be
+;; considered, and shrinking always proceeds from the left to the right.
+(define (candidate-sizes lolon)
+  (define all-boxes (map (λ (x) (box (sort x >=))) lolon))
+  (define answer '())
+  (define (record-current)
+    (set! answer (cons (map car (map unbox all-boxes)) answer)))
+  (for ([box (in-list all-boxes)])
+    (for ([i (in-range (- (length (unbox box)) 1))])
+      (record-current)
+      (set-box! box (cdr (unbox box)))))
+  (record-current)
+  (reverse answer))
+
+(module+ test
+  (require rackunit)
+  
+  (define (log-em lolon) (candidate-sizes lolon))
+  
+  (check-equal? (log-em '((1)))
+                (list '(1)))
+  (check-equal? (log-em '((1) (2) (3)))
+                (list '(1 2 3)))
+  (check-equal? (log-em '((4 3 2 1)))
+                (list '(4) '(3) '(2) '(1)))
+  (check-equal? (log-em '((1 2 3 4)))
+                (list '(4) '(3) '(2) '(1)))
+  (check-equal? (log-em '((5 1) (6 2) (7 3)))
+                (list '(5 6 7)
+                      '(1 6 7)
+                      '(1 2 7)
+                      '(1 2 3)))
+  (check-equal? (log-em '((10 9 8) (7 6 5)))
+                (list '(10 7)
+                      '(9 7)
+                      '(8 7)
+                      '(8 6)
+                      '(8 5))))
diff --git a/collects/framework/private/sig.rkt b/collects/framework/private/sig.rkt
index e4f9511d94..e0fe6b2b73 100644
--- a/collects/framework/private/sig.rkt
+++ b/collects/framework/private/sig.rkt
@@ -60,7 +60,13 @@
      horizontal-dragable%
 
      splitter<%>
-     splitter-mixin))
+     splitter-mixin
+     
+     discrete-sizes<%>
+     discrete-child<%>
+     discrete-sizes-mixin
+     horizontal-discrete-sizes%
+     vertical-discrete-sizes%))
   (define-signature panel^ extends panel-class^
     (dragable-container-size
      dragable-place-children))
diff --git a/collects/gui-debugger/debug-tool.rkt b/collects/gui-debugger/debug-tool.rkt
index bfa60c5f6b..8fd850684c 100644
--- a/collects/gui-debugger/debug-tool.rkt
+++ b/collects/gui-debugger/debug-tool.rkt
@@ -1391,7 +1391,7 @@
                (label (string-constant debug-tool-button-name))
                (bitmap debug-bitmap)
                (alternate-bitmap small-debug-bitmap)
-               (parent (new vertical-pane%
+               (parent (new panel:horizontal-discrete-sizes%
                             [parent (get-button-panel)]
                             [alignment '(center center)]))
                (callback (λ (button) (debug-callback)))))
@@ -1526,9 +1526,9 @@
                   (send (send debug-button get-parent) delete-child debug-button)))))
         
         (send (get-button-panel) change-children
-              (lambda (_)
+              (lambda (children)
                 (cons (send debug-button get-parent)
-                      (remq (send debug-button get-parent) _))))
+                      (remq (send debug-button get-parent) children))))
         
         ; hide debug button if it's not supported for the initial language:
         (check-current-language-for-debugger)))
diff --git a/collects/handin-client/client-gui.rkt b/collects/handin-client/client-gui.rkt
index 3912a64740..f2b1d7e5ec 100644
--- a/collects/handin-client/client-gui.rkt
+++ b/collects/handin-client/client-gui.rkt
@@ -783,7 +783,7 @@
           (super help-menu:after-about menu))
 
         (define client-panel
-          (new vertical-pane% (parent (get-button-panel))))
+          (new panel:vertical-discrete-sizes% (parent (get-button-panel))))
 
         (define client-button
           (new switchable-button%
diff --git a/collects/macro-debugger/tool.rkt b/collects/macro-debugger/tool.rkt
index f5716694d1..6ee7db2b57 100644
--- a/collects/macro-debugger/tool.rkt
+++ b/collects/macro-debugger/tool.rkt
@@ -127,10 +127,8 @@
                  get-current-tab)
 
         (define macro-debug-panel
-          (new horizontal-pane%
-               (parent (get-button-panel))
-               (stretchable-height #f)
-               (stretchable-width #f)))
+          (new panel:horizontal-discrete-sizes%
+               (parent (get-button-panel))))
         (define macro-debug-button
           (new switchable-button%
                (label macro-stepper-button-label)
diff --git a/collects/mrlib/scribblings/switchable-button.scrbl b/collects/mrlib/scribblings/switchable-button.scrbl
index 74d040a265..da89b4e294 100644
--- a/collects/mrlib/scribblings/switchable-button.scrbl
+++ b/collects/mrlib/scribblings/switchable-button.scrbl
@@ -1,5 +1,5 @@
 #lang scribble/doc
-@(require "common.rkt" (for-label mrlib/switchable-button))
+@(require "common.rkt" (for-label mrlib/switchable-button framework))
 
 @title{Switchable Button}
 
@@ -12,21 +12,32 @@
   display of just the icon and a display with the 
   label and the icon side-by-side. 
   
-  @defconstructor/auto-super[([label string?]
-                              [callback (-> (is-a?/c switchable-button%) any/c)]
+  The @racket[panel:discrete-sizes-mixin] explicitly
+  uses @racket[switchable-button%]s via their
+  @method[switchable-button% get-small-width] and
+  @method[switchable-button% get-small-height] methods.
+  See @racket[panel:discrete-sizes-mixin] for more details.
+  
+  @defconstructor/auto-super[([label (or/c string? (is-a?/c bitmap%) #f)]
                               [bitmap (is-a?/c bitmap%)]
+                              [callback (-> (is-a?/c switchable-button%) any/c)]
                               [alternate-bitmap (is-a?/c bitmap%) bitmap]
-                              [vertical-tight? boolean? #f])]{
+                              [vertical-tight? boolean? #f]
+                              [min-width-includes-label? boolean? #f])]{
     The @racket[callback] is called when the button
-    is pressed. The @racket[string] and @racket[bitmap] are
+    is pressed. The @racket[label] and @racket[bitmap] are
     used as discussed above.
     
     If @racket[alternate-bitmap] is supplied, then it is used
-    when the button is switched to the view that just shows the bitmap.
-    If it is not supplied, both modes show the same bitmap.
+    when the label is not visible (via a call to @method[switchable-button% set-label-visible]).
+    If it is not supplied, both modes show @racket[bitmap].
     
     If the @racket[vertical-tight?] argument is @racket[#t], then the button takes up
     as little as possible vertical space.
+    
+    If the @racket[min-width-includes-label?] is @racket[#t], then the minimum
+    width includes both the bitmap and the label. Otherwise, it includes
+    only the bitmap.
   }
   
   @defmethod[(set-label-visible [visible? boolean?]) void?]{
@@ -40,4 +51,19 @@
   @defmethod[(get-button-label) string?]{
     Returns the label of this button.
   }
+  
+  @defmethod[(get-large-width) exact-nonnegative-integer?]{
+     Returns the width of the button when it would show both
+     the label and the bitmap and when it is in label-visible
+     mode (i.e., when @racket[set-label-visible] has been called
+     with @racket[#t]).
+  }
+
+  @defmethod[(get-small-width) exact-nonnegative-integer?]{
+     Returns the width of the button when it would show both
+     just the bitmap (not the alternate bitmap),
+     and when it is in label-visible
+     mode (i.e., when @racket[set-label-visible] has been called
+     with @racket[#t]).
+  }
 }
diff --git a/collects/mrlib/switchable-button.rkt b/collects/mrlib/switchable-button.rkt
index 442589547a..b9838caa4e 100644
--- a/collects/mrlib/switchable-button.rkt
+++ b/collects/mrlib/switchable-button.rkt
@@ -1,6 +1,6 @@
-#lang scheme/base
-(require scheme/gui/base
-         scheme/class)
+#lang racket/base
+(require racket/gui/base
+         racket/class)
 
 (provide switchable-button%)
 (define gap 4) ;; space between the text and the icon
@@ -57,7 +57,8 @@
                 bitmap
                 callback
                 [alternate-bitmap bitmap]
-                [vertical-tight? #f])
+                [vertical-tight? #f]
+                [min-width-includes-label? #f])
     
     (define/public (get-button-label) label)
     
@@ -206,13 +207,13 @@
             ;; Draw background. Use alpha blending if it can work,
             ;;  otherwise fall back to a suitable color.
             (let ([color (cond
-                          [disabled? #f]
-                          [in? (if (eq? (send dc get-smoothing) 'aligned)
-                                   (if down? 0.5 0.2)
-                                   (if down?
-                                       half-gray
-                                       one-fifth-gray))]
-                          [else #f])])
+                           [disabled? #f]
+                           [in? (if (eq? (send dc get-smoothing) 'aligned)
+                                    (if down? 0.5 0.2)
+                                    (if down?
+                                        half-gray
+                                        one-fifth-gray))]
+                           [else #f])])
               (when color
                 (send dc set-pen "black" 1 'transparent)
                 (send dc set-brush (if (number? color) "black" color) 'solid)
@@ -232,14 +233,19 @@
               (send dc set-alpha .5))
             
             (cond
-              [with-label? 
-               (let-values ([(tw th _1 _2) (send dc get-text-extent label)])
-                 (let ([text-start (+ (/ cw 2) 
-                                      (- (/ tw 2))
-                                      (- (/ (send bitmap get-width) 2))
-                                      (- rhs-pad))])
-                   (send dc draw-text label text-start (- (/ ch 2) (/ th 2)))
-                   (draw-the-bitmap (+ text-start tw gap) (- (/ ch 2) (/ (send bitmap get-height) 2)))))]
+              [with-label?
+               (cond
+                 [(<= cw (get-small-width))
+                  (draw-the-bitmap (- (/ cw 2) (/ (send bitmap get-width) 2)) 
+                                   (- (/ ch 2) (/ (send bitmap get-height) 2)))]
+                 [else
+                  (define-values (tw th _1 _2) (send dc get-text-extent label))
+                  (define text-start (+ (/ cw 2) 
+                                        (- (/ tw 2))
+                                        (- (/ (send bitmap get-width) 2))
+                                        (- rhs-pad)))
+                  (send dc draw-text label text-start (- (/ ch 2) (/ th 2)))
+                  (draw-the-bitmap (+ text-start tw gap) (- (/ ch 2) (/ (send bitmap get-height) 2)))])]
               [else
                (draw-the-bitmap (- (/ cw 2) (/ (send (if with-label? bitmap alternate-bitmap) get-width) 2))
                                 (- (/ ch 2) (/ (send (if with-label? bitmap alternate-bitmap) get-height) 2)))])
@@ -268,22 +274,53 @@
         (refresh)))
     
     (define/private (update-sizes)
-      (let ([dc (get-dc)])
-        (cond
-          [with-label?
-           (let-values ([(w h _1 _2) (send dc get-text-extent label normal-control-font)])
-             (do-w/h (+ w gap (send bitmap get-width) rhs-pad)
-                     (max h (send bitmap get-height))))]
-          [else
-           (do-w/h (send alternate-bitmap get-width)
-                   (send alternate-bitmap get-height))])))
+      (define dc (get-dc))
+      (define-values (tw th _1 _2) (send dc get-text-extent label normal-control-font))
+      (define h 
+        (inexact->exact 
+         (floor
+          (+ (max th
+                  (send alternate-bitmap get-height)
+                  (send bitmap get-height))
+             h-circle-space margin margin 
+             (if vertical-tight? -6 0)))))
+      (cond
+        [with-label?
+         (cond
+           [min-width-includes-label?
+            (min-width (get-large-width))]
+           [else
+            (min-width (get-small-width))])
+         (min-height h)]
+        [else
+         (min-width (get-without-label-small-width))
+         (min-height h)]))
     
-    (define/private (do-w/h w h)
-      (let ([w (floor (inexact->exact w))]
-            [h (floor (inexact->exact h))])
-        (min-width (+ w w-circle-space margin margin))
-        (min-height (+ h h-circle-space margin margin 
-                       (if vertical-tight? -6 0)))))
+    (define/public (get-large-width)
+      (define dc (get-dc))
+      (define-values (tw th _1 _2) (send dc get-text-extent label normal-control-font))
+      (inexact->exact
+       (floor
+        (+ (+ tw gap (send bitmap get-width) rhs-pad)
+           w-circle-space
+           margin
+           margin))))
+    
+    (define/private (get-without-label-small-width)
+      (inexact->exact
+       (floor
+        (+ (send alternate-bitmap get-width)
+           w-circle-space
+           margin
+           margin))))
+    
+    (define/public (get-small-width)
+      (inexact->exact
+       (floor
+        (+ (send bitmap get-width)
+           w-circle-space
+           margin
+           margin))))
     
     (super-new [style '(transparent no-focus)])
     (send (get-dc) set-smoothing 'aligned)
diff --git a/collects/scribblings/framework/panel.scrbl b/collects/scribblings/framework/panel.scrbl
index 8695dfed8e..aad7df0aa2 100644
--- a/collects/scribblings/framework/panel.scrbl
+++ b/collects/scribblings/framework/panel.scrbl
@@ -1,7 +1,6 @@
 #lang scribble/doc
 @(require scribble/manual scribble/extract)
-@(require (for-label framework))
-@(require (for-label scheme/gui))
+@(require (for-label framework mrlib/switchable-button racket/gui))
 @title{Panel}
 
 @definterface[panel:single<%> (area-container<%>)]{
@@ -219,4 +218,59 @@
 
 }
 
+@definterface[panel:discrete-sizes<%> ()]{
+  Classes implementing this interface support children
+  with multiple fixed sizes. As the panel is resized,
+  it calculates a set of sizes of its children
+  that fills its available size and approtions the space accordingly
+  using only one of the fixed sizes.
+  
+  The strategy it uses is to try to give the largest of
+  the sizes to children that appear later in
+  the list of children (to the right horizontal and lower
+  vertically). It does not try all possible combinations.
+  
+  Each child that supports minimum sizes is expected to
+  implement the @racket[panel:discrete-child<%>] interface.
+  Children that do not implement this interface are just
+  treated like @racket[horizontal-panel%] or @racket[vertical-panel%]
+  would treat them, with the exception of 
+  @racket[switchable-button%]. In that case, the
+  results of
+  @method[switchable-button% get-small-width] and
+  @method[switchable-button% get-large-width] are 
+  treated as the two fixed sizes for instances of that class.
+
+  Also note that, the orientation of the panel determines whether
+  or not it treats heights or widths as described above. That is,
+  when a panel is in vertical mode, it ignores the horizontal
+  discrete sizes, and vice-versa.
+  
+  @defmethod[(set-orientation [horizontal? boolean?]) void?]{
+    Changes the orientation of the panel.                                                           
+  }
+  @defmethod[(get-orientation) boolean?]{
+    Returns the current orientation of the panel.                                                           
+  }
+}
+
+@definterface[panel:discrete-child<%> ()]{
+   Classes that implement this method collaborate with 
+   @racket[panel:discrete-sizes<%>] to indicate 
+   which fixed sizes they support.
+                                          
+  @defmethod[(get-discrete-widths) (listof exact-nonnegative-integer?)]{
+     Return a list of widths this class supports.
+  }
+  @defmethod[(get-discrete-heights) (listof exact-nonnegative-integer?)]{    
+     Return a list of heights this class supports.
+  }
+}
+
+@defmixin[panel:discrete-sizes-mixin (panel%) (panel:discrete-sizes<%> panel:discrete-child<%>)]{
+   Provides an implementation of @racket[panel:discrete-sizes<%>].
+                                 
+   It uses the sizes of its children to implement the @racket[panel:discrete-child<%>] interface.
+}
+
 @(include-previously-extracted "main-extracts.rkt" #rx"^panel:")
diff --git a/collects/stepper/stepper-tool.rkt b/collects/stepper/stepper-tool.rkt
index 6c95660e7b..62158aa0c6 100644
--- a/collects/stepper/stepper-tool.rkt
+++ b/collects/stepper/stepper-tool.rkt
@@ -173,7 +173,7 @@
       (define/public (get-stepper-button) stepper-button)
       
       (define stepper-button-parent-panel 
-        (new horizontal-panel%
+        (new frame:panel:horizontal-discrete-sizes%
              [parent (get-button-panel)]
              [stretchable-width #f]
              [stretchable-height #f]))