diff --git a/collects/mred/private/kernel.ss b/collects/mred/private/kernel.ss
index 7c257f25ab..7b5042e6a5 100644
--- a/collects/mred/private/kernel.ss
+++ b/collects/mred/private/kernel.ss
@@ -78,9 +78,9 @@
 		   (syntax
 		    (define name (let ([c (dynamic-require ''#%mred-kernel 'name)])
 				   (make-primitive-class
-				    (lambda (class prop:object preparer dispatcher unwrapper more-props)
+				    (lambda (class prop:object preparer dispatcher prop:unwrap unwrapper more-props)
 				      (kernel:primitive-class-prepare-struct-type! 
-				       c prop:object class preparer dispatcher unwrapper more-props))
+				       c prop:object class preparer dispatcher prop:unwrap unwrapper more-props))
 				    kernel:initialize-primitive-object
 				    'print-name super (list intf ...) 'args
 				    '(old ...)
diff --git a/collects/scheme/private/class-internal.ss b/collects/scheme/private/class-internal.ss
index 28dd9f988e..b42092c0c0 100644
--- a/collects/scheme/private/class-internal.ss
+++ b/collects/scheme/private/class-internal.ss
@@ -209,10 +209,9 @@
             (lambda (o v) (set! o 0 v))
             struct:wrapper-object)))
 
-;; unwrap-object : (union wrapper-object object) -> object
-;; wrapped objects can only be one level deep, so just do a quick check and unwrap.
-(define (unwrap-object o)
-  (if (wrapper-object? o) (wrapper-object-wrapped o) o))
+(define-values (prop:unwrap object-unwrapper)
+  (let-values ([(prop:unwrap pred acc) (make-struct-type-property 'prop:unwrap)])
+    (values prop:unwrap acc)))
 
 ;;--------------------------------------------------------------------
 ;;  class macros
@@ -1185,7 +1184,7 @@
                                      (make-field-map trace-flag
                                                      (quote-syntax the-finder)
                                                      (quote the-obj)
-                                                     (quote-syntax unwrap-object)
+                                                     (quote-syntax (λ (o) ((object-unwrapper o) o)))
                                                      (quote-syntax inherit-field-name)
                                                      (quote-syntax inherit-field-name-localized)
                                                      (quote-syntax inherit-field-accessor)
@@ -1195,7 +1194,7 @@
                                      (make-field-map trace-flag
                                                      (quote-syntax the-finder)
                                                      (quote the-obj)
-                                                     (quote-syntax unwrap-object)
+                                                     (quote-syntax (λ (o) ((object-unwrapper o) o)))
                                                      (quote-syntax local-field)
                                                      (quote-syntax local-field-localized)
                                                      (quote-syntax local-field-accessor)
@@ -2124,7 +2123,10 @@
             ;; --- Make the new object struct ---
             (let*-values ([(prim-object-make prim-object? struct:prim-object)
                            (if make-struct:prim
-                               (make-struct:prim c prop:object preparer dispatcher unwrap-object (get-properties interfaces))
+                               (make-struct:prim c prop:object 
+                                                 preparer dispatcher
+                                                 prop:unwrap values
+                                                 (get-properties interfaces))
                                (values #f #f #f))]
                           [(struct:object object-make object? object-field-ref object-field-set!)
                            (if make-struct:prim
@@ -2139,6 +2141,7 @@
                                                  ;; Map object property to class:
                                                  (append
                                                   (list (cons prop:object c))
+                                                  (list (cons prop:unwrap values))
                                                   (if deserialize-id
                                                       (list
                                                        (cons prop:serializable
@@ -2680,7 +2683,8 @@
                                         0 ;; No new fields in this class replacement
                                         undefined
                                         ;; Map object property to class:
-                                        (list (cons prop:object c)))])
+                                        (list (cons prop:object c)
+                                              (cons prop:unwrap values)))])
           (set-class-struct:object! c struct:object)
           (set-class-object?! c object?)
           (set-class-make-object! c object-make)
@@ -3306,7 +3310,8 @@
 (vector-set! (class-supers object%) 0 object%)
 (set-class-orig-cls! object% object%)
 (let*-values ([(struct:obj make-obj obj? -get -set!)
-               (make-struct-type 'object #f 0 0 #f (list (cons prop:object object%)) #f)])
+               (make-struct-type 'object #f 0 0 #f (list (cons prop:object object%)
+                                                         (cons prop:unwrap values)) #f)])
   (set-class-struct:object! object% struct:obj)
   (set-class-make-object! object% make-obj))
 (set-class-object?! object% object?) ; don't use struct pred; it wouldn't work with prim classes
@@ -3598,7 +3603,7 @@
               traced?
               stx
               (syntax/loc stx receiver)
-              (syntax/loc stx unwrap-object)
+              (syntax/loc stx (λ (o) ((object-unwrapper o) o)))
               (syntax/loc stx method)
               (syntax/loc stx sym)
               args
@@ -3761,7 +3766,7 @@
                      traced?
                      stx
                      (syntax obj)
-                     (syntax/loc stx unwrap-object)
+                     (syntax/loc stx (λ (o) ((object-unwrapper o) o)))
                      (syntax/loc stx ((generic-applicable gen) obj))
                      (syntax/loc stx (generic-name gen))
                      flat-stx
@@ -3843,7 +3848,7 @@
           [field-ht (class-field-ht cls)]
           [index (hash-ref field-ht id #f)])
      (if index
-         ((vector-ref (class-ext-field-sets cls) index) (unwrap-object obj) val)
+         ((vector-ref (class-ext-field-sets cls) index) ((object-unwrapper obj) obj) val)
          (raise-mismatch-error 
           'get-field
           (format "expected an object that has a field named ~s, got " id)
@@ -3879,7 +3884,7 @@
           [field-ht (class-field-ht cls)]
           [index (hash-ref field-ht id #f)])
      (if index
-         ((vector-ref (class-ext-field-refs cls) index) (unwrap-object obj))
+         ((vector-ref (class-ext-field-refs cls) index) ((object-unwrapper obj) obj))
          (raise-mismatch-error 
           'get-field
           (format "expected an object that has a field named ~s, got " id)
@@ -3965,7 +3970,7 @@
                                                                  (quote-syntax id)
                                                                  (quote-syntax method)
                                                                  (quote-syntax method-obj)
-                                                                 (syntax unwrap-object))]
+                                                                 (syntax (λ (o) ((object-unwrapper o) o))))]
                                                           ...)
                                    ()
                                    body0 body1 ...)))))]
@@ -4018,10 +4023,10 @@
    (trace (when (object? v)
             (inspect-event v)))
    (cond
-     [(class? c) ((class-object? (class-orig-cls c)) (unwrap-object v))]
+     [(class? c) ((class-object? (class-orig-cls c)) ((object-unwrapper v) v))]
      [(interface? c)
       (and (object? v)
-           (implementation? (object-ref (unwrap-object v)) c))]
+           (implementation? (object-ref ((object-unwrapper v) v)) c))]
      [else (raise-type-error 'is-a? "class or interface" 1 v c)])))
 
 (define (subclass? v c)
@@ -4039,7 +4044,7 @@
     (raise-type-error 'object-interface "object" o))
   (trace-begin
    (trace (inspect-event o))
-   (class-self-interface (object-ref (unwrap-object o)))))
+   (class-self-interface (object-ref ((object-unwrapper o) o)))))
 
 (define-traced (object-method-arity-includes? o name cnt)
   (unless (object? o)
@@ -4098,7 +4103,7 @@
     (raise-type-error 'object-info "object" o))
   (trace-begin
    (trace (inspect-event o))
-   (let loop ([c (object-ref (unwrap-object o))]
+   (let loop ([c (object-ref ((object-unwrapper o) o))]
               [skipped? #f])
      (if (struct? ((class-insp-mk c)))
          ;; current inspector can inspect this object
@@ -4138,7 +4143,7 @@
       (raise-type-error 'object->vector "object" in-o))
     (trace-begin
      (trace (inspect-event in-o))
-     (let ([o (unwrap-object in-o)])
+     (let ([o ((object-unwrapper in-o) in-o)])
        (list->vector
         (cons
          (string->symbol (format "object:~a" (class-name (object-ref o))))
@@ -4165,8 +4170,8 @@
     (raise-type-error 'object=? "object" o1))
   (unless (object? o2)
     (raise-type-error 'object=? "object" o2))
-  (eq? (unwrap-object o1)
-       (unwrap-object o2)))
+  (eq? ((object-unwrapper o1) o1)
+       ((object-unwrapper o2) o2)))
 
 ;;--------------------------------------------------------------------
 ;;  primitive classes
@@ -4334,7 +4339,8 @@
                                     0 ;; No new fields in this wrapped object
                                     undefined
                                     ;; Map object property to class:
-                                    (list (cons prop:object c)))])
+                                    (list (cons prop:object c)
+                                          (cons prop:unwrap wrapper-object-wrapped)))])
       (set-class-struct:object! c struct:object)
       (set-class-object?! c object?)
       (set-class-make-object! c object-make)
@@ -4382,7 +4388,7 @@
 (define (make-wrapper-object obj blame methods method-contracts fields field-contracts)
   (check-object-contract obj blame methods fields)
   (let ([new-cls (make-wrapper-class (object-ref obj) blame methods method-contracts fields field-contracts)])
-    ((class-make-object new-cls) (unwrap-object obj))))
+    ((class-make-object new-cls) ((object-unwrapper obj) obj))))
 
 ;;--------------------------------------------------------------------
 ;;  misc utils
diff --git a/src/mred/wxs/wxs_bmap.cxx b/src/mred/wxs/wxs_bmap.cxx
index 0f76c79987..5f768261a1 100644
--- a/src/mred/wxs/wxs_bmap.cxx
+++ b/src/mred/wxs/wxs_bmap.cxx
@@ -659,7 +659,7 @@ int objscheme_istype_wxBitmap(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxBitmap_class);
   if (objscheme_is_a(obj, os_wxBitmap_class))
     return 1;
   else {
@@ -703,7 +703,7 @@ class wxBitmap *objscheme_unbundle_wxBitmap(Scheme_Object *obj, const char *wher
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxBitmap_class);
   (void)objscheme_istype_wxBitmap(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_butn.cxx b/src/mred/wxs/wxs_butn.cxx
index c76e2ef8aa..4381a4cb82 100644
--- a/src/mred/wxs/wxs_butn.cxx
+++ b/src/mred/wxs/wxs_butn.cxx
@@ -796,7 +796,7 @@ int objscheme_istype_wxButton(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxButton_class);
   if (objscheme_is_a(obj, os_wxButton_class))
     return 1;
   else {
@@ -840,7 +840,7 @@ class wxButton *objscheme_unbundle_wxButton(Scheme_Object *obj, const char *wher
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxButton_class);
   (void)objscheme_istype_wxButton(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_chce.cxx b/src/mred/wxs/wxs_chce.cxx
index 75e7408e0f..51b0d790e0 100644
--- a/src/mred/wxs/wxs_chce.cxx
+++ b/src/mred/wxs/wxs_chce.cxx
@@ -899,7 +899,7 @@ int objscheme_istype_wxChoice(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxChoice_class);
   if (objscheme_is_a(obj, os_wxChoice_class))
     return 1;
   else {
@@ -943,7 +943,7 @@ class wxChoice *objscheme_unbundle_wxChoice(Scheme_Object *obj, const char *wher
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxChoice_class);
   (void)objscheme_istype_wxChoice(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_ckbx.cxx b/src/mred/wxs/wxs_ckbx.cxx
index 67d1a977fd..0e6f50dc7b 100644
--- a/src/mred/wxs/wxs_ckbx.cxx
+++ b/src/mred/wxs/wxs_ckbx.cxx
@@ -821,7 +821,7 @@ int objscheme_istype_wxCheckBox(Scheme_Object *obj, const char *stop, int nullOK
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxCheckBox_class);
   if (objscheme_is_a(obj, os_wxCheckBox_class))
     return 1;
   else {
@@ -865,7 +865,7 @@ class wxCheckBox *objscheme_unbundle_wxCheckBox(Scheme_Object *obj, const char *
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxCheckBox_class);
   (void)objscheme_istype_wxCheckBox(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_cnvs.cxx b/src/mred/wxs/wxs_cnvs.cxx
index 1dde33c3c9..0eae07105f 100644
--- a/src/mred/wxs/wxs_cnvs.cxx
+++ b/src/mred/wxs/wxs_cnvs.cxx
@@ -1419,7 +1419,7 @@ int objscheme_istype_wxCanvas(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxCanvas_class);
   if (objscheme_is_a(obj, os_wxCanvas_class))
     return 1;
   else {
@@ -1463,7 +1463,7 @@ class wxCanvas *objscheme_unbundle_wxCanvas(Scheme_Object *obj, const char *wher
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxCanvas_class);
   (void)objscheme_istype_wxCanvas(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_dc.cxx b/src/mred/wxs/wxs_dc.cxx
index 59b7f993cf..9f21d5f238 100644
--- a/src/mred/wxs/wxs_dc.cxx
+++ b/src/mred/wxs/wxs_dc.cxx
@@ -2664,7 +2664,7 @@ int objscheme_istype_wxDC(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxDC_class);
   if (objscheme_is_a(obj, os_wxDC_class))
     return 1;
   else {
@@ -2708,7 +2708,7 @@ class wxDC *objscheme_unbundle_wxDC(Scheme_Object *obj, const char *where, int n
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxDC_class);
   (void)objscheme_istype_wxDC(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -3116,7 +3116,7 @@ int objscheme_istype_wxMemoryDC(Scheme_Object *obj, const char *stop, int nullOK
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxMemoryDC_class);
   if (objscheme_is_a(obj, os_wxMemoryDC_class))
     return 1;
   else {
@@ -3160,7 +3160,7 @@ class wxMemoryDC *objscheme_unbundle_wxMemoryDC(Scheme_Object *obj, const char *
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxMemoryDC_class);
   (void)objscheme_istype_wxMemoryDC(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -3281,7 +3281,7 @@ int objscheme_istype_wxPostScriptDC(Scheme_Object *obj, const char *stop, int nu
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPostScriptDC_class);
   if (objscheme_is_a(obj, os_wxPostScriptDC_class))
     return 1;
   else {
@@ -3325,7 +3325,7 @@ class wxPostScriptDC *objscheme_unbundle_wxPostScriptDC(Scheme_Object *obj, cons
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPostScriptDC_class);
   (void)objscheme_istype_wxPostScriptDC(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -3467,7 +3467,7 @@ int objscheme_istype_basePrinterDC(Scheme_Object *obj, const char *stop, int nul
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_basePrinterDC_class);
   if (objscheme_is_a(obj, os_basePrinterDC_class))
     return 1;
   else {
@@ -3511,7 +3511,7 @@ class basePrinterDC *objscheme_unbundle_basePrinterDC(Scheme_Object *obj, const
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_basePrinterDC_class);
   (void)objscheme_istype_basePrinterDC(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -3671,7 +3671,7 @@ int objscheme_istype_wxGL(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxGL_class);
   if (objscheme_is_a(obj, os_wxGL_class))
     return 1;
   else {
@@ -3715,7 +3715,7 @@ class wxGL *objscheme_unbundle_wxGL(Scheme_Object *obj, const char *where, int n
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxGL_class);
   (void)objscheme_istype_wxGL(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -4029,7 +4029,7 @@ int objscheme_istype_wxGLConfig(Scheme_Object *obj, const char *stop, int nullOK
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxGLConfig_class);
   if (objscheme_is_a(obj, os_wxGLConfig_class))
     return 1;
   else {
@@ -4073,7 +4073,7 @@ class wxGLConfig *objscheme_unbundle_wxGLConfig(Scheme_Object *obj, const char *
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxGLConfig_class);
   (void)objscheme_istype_wxGLConfig(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_evnt.cxx b/src/mred/wxs/wxs_evnt.cxx
index 3d23f9f748..019fd2d8f6 100644
--- a/src/mred/wxs/wxs_evnt.cxx
+++ b/src/mred/wxs/wxs_evnt.cxx
@@ -232,7 +232,7 @@ int objscheme_istype_wxEvent(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxEvent_class);
   if (objscheme_is_a(obj, os_wxEvent_class))
     return 1;
   else {
@@ -275,7 +275,7 @@ class wxEvent *objscheme_unbundle_wxEvent(Scheme_Object *obj, const char *where,
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxEvent_class);
   (void)objscheme_istype_wxEvent(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -502,7 +502,7 @@ int objscheme_istype_wxCommandEvent(Scheme_Object *obj, const char *stop, int nu
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxCommandEvent_class);
   if (objscheme_is_a(obj, os_wxCommandEvent_class))
     return 1;
   else {
@@ -545,7 +545,7 @@ class wxCommandEvent *objscheme_unbundle_wxCommandEvent(Scheme_Object *obj, cons
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxCommandEvent_class);
   (void)objscheme_istype_wxCommandEvent(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -682,7 +682,7 @@ int objscheme_istype_wxPopupEvent(Scheme_Object *obj, const char *stop, int null
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPopupEvent_class);
   if (objscheme_is_a(obj, os_wxPopupEvent_class))
     return 1;
   else {
@@ -725,7 +725,7 @@ class wxPopupEvent *objscheme_unbundle_wxPopupEvent(Scheme_Object *obj, const ch
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPopupEvent_class);
   (void)objscheme_istype_wxPopupEvent(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -1041,7 +1041,7 @@ int objscheme_istype_wxScrollEvent(Scheme_Object *obj, const char *stop, int nul
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxScrollEvent_class);
   if (objscheme_is_a(obj, os_wxScrollEvent_class))
     return 1;
   else {
@@ -1084,7 +1084,7 @@ class wxScrollEvent *objscheme_unbundle_wxScrollEvent(Scheme_Object *obj, const
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxScrollEvent_class);
   (void)objscheme_istype_wxScrollEvent(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -2119,7 +2119,7 @@ int objscheme_istype_wxKeyEvent(Scheme_Object *obj, const char *stop, int nullOK
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxKeyEvent_class);
   if (objscheme_is_a(obj, os_wxKeyEvent_class))
     return 1;
   else {
@@ -2162,7 +2162,7 @@ class wxKeyEvent *objscheme_unbundle_wxKeyEvent(Scheme_Object *obj, const char *
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxKeyEvent_class);
   (void)objscheme_istype_wxKeyEvent(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -3019,7 +3019,7 @@ int objscheme_istype_wxMouseEvent(Scheme_Object *obj, const char *stop, int null
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxMouseEvent_class);
   if (objscheme_is_a(obj, os_wxMouseEvent_class))
     return 1;
   else {
@@ -3062,7 +3062,7 @@ class wxMouseEvent *objscheme_unbundle_wxMouseEvent(Scheme_Object *obj, const ch
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxMouseEvent_class);
   (void)objscheme_istype_wxMouseEvent(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_fram.cxx b/src/mred/wxs/wxs_fram.cxx
index e61cf27edc..5a62c2e802 100644
--- a/src/mred/wxs/wxs_fram.cxx
+++ b/src/mred/wxs/wxs_fram.cxx
@@ -1448,7 +1448,7 @@ int objscheme_istype_wxFrame(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxFrame_class);
   if (objscheme_is_a(obj, os_wxFrame_class))
     return 1;
   else {
@@ -1492,7 +1492,7 @@ class wxFrame *objscheme_unbundle_wxFrame(Scheme_Object *obj, const char *where,
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxFrame_class);
   (void)objscheme_istype_wxFrame(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_gage.cxx b/src/mred/wxs/wxs_gage.cxx
index da11ef6cfa..ae194545c9 100644
--- a/src/mred/wxs/wxs_gage.cxx
+++ b/src/mred/wxs/wxs_gage.cxx
@@ -756,7 +756,7 @@ int objscheme_istype_wxsGauge(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxsGauge_class);
   if (objscheme_is_a(obj, os_wxsGauge_class))
     return 1;
   else {
@@ -800,7 +800,7 @@ class wxsGauge *objscheme_unbundle_wxsGauge(Scheme_Object *obj, const char *wher
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxsGauge_class);
   (void)objscheme_istype_wxsGauge(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_gdi.cxx b/src/mred/wxs/wxs_gdi.cxx
index 681b1a324f..2658e9f731 100644
--- a/src/mred/wxs/wxs_gdi.cxx
+++ b/src/mred/wxs/wxs_gdi.cxx
@@ -686,7 +686,7 @@ int objscheme_istype_wxFont(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxFont_class);
   if (objscheme_is_a(obj, os_wxFont_class))
     return 1;
   else {
@@ -730,7 +730,7 @@ class wxFont *objscheme_unbundle_wxFont(Scheme_Object *obj, const char *where, i
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxFont_class);
   (void)objscheme_istype_wxFont(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -934,7 +934,7 @@ int objscheme_istype_wxFontList(Scheme_Object *obj, const char *stop, int nullOK
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxFontList_class);
   if (objscheme_is_a(obj, os_wxFontList_class))
     return 1;
   else {
@@ -978,7 +978,7 @@ class wxFontList *objscheme_unbundle_wxFontList(Scheme_Object *obj, const char *
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxFontList_class);
   (void)objscheme_istype_wxFontList(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -1320,7 +1320,7 @@ int objscheme_istype_wxColour(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxColour_class);
   if (objscheme_is_a(obj, os_wxColour_class))
     return 1;
   else {
@@ -1364,7 +1364,7 @@ class wxColour *objscheme_unbundle_wxColour(Scheme_Object *obj, const char *wher
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxColour_class);
   (void)objscheme_istype_wxColour(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -1461,7 +1461,7 @@ int objscheme_istype_wxColourDatabase(Scheme_Object *obj, const char *stop, int
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxColourDatabase_class);
   if (objscheme_is_a(obj, os_wxColourDatabase_class))
     return 1;
   else {
@@ -1505,7 +1505,7 @@ class wxColourDatabase *objscheme_unbundle_wxColourDatabase(Scheme_Object *obj,
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxColourDatabase_class);
   (void)objscheme_istype_wxColourDatabase(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -1710,7 +1710,7 @@ int objscheme_istype_wxPoint(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPoint_class);
   if (objscheme_is_a(obj, os_wxPoint_class))
     return 1;
   else {
@@ -1753,7 +1753,7 @@ class wxPoint *objscheme_unbundle_wxPoint(Scheme_Object *obj, const char *where,
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPoint_class);
   (void)objscheme_istype_wxPoint(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -2274,7 +2274,7 @@ int objscheme_istype_wxBrush(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxBrush_class);
   if (objscheme_is_a(obj, os_wxBrush_class))
     return 1;
   else {
@@ -2318,7 +2318,7 @@ class wxBrush *objscheme_unbundle_wxBrush(Scheme_Object *obj, const char *where,
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxBrush_class);
   (void)objscheme_istype_wxBrush(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -2471,7 +2471,7 @@ int objscheme_istype_wxBrushList(Scheme_Object *obj, const char *stop, int nullO
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxBrushList_class);
   if (objscheme_is_a(obj, os_wxBrushList_class))
     return 1;
   else {
@@ -2515,7 +2515,7 @@ class wxBrushList *objscheme_unbundle_wxBrushList(Scheme_Object *obj, const char
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxBrushList_class);
   (void)objscheme_istype_wxBrushList(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -3085,7 +3085,7 @@ int objscheme_istype_wxPen(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPen_class);
   if (objscheme_is_a(obj, os_wxPen_class))
     return 1;
   else {
@@ -3129,7 +3129,7 @@ class wxPen *objscheme_unbundle_wxPen(Scheme_Object *obj, const char *where, int
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPen_class);
   (void)objscheme_istype_wxPen(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -3287,7 +3287,7 @@ int objscheme_istype_wxPenList(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPenList_class);
   if (objscheme_is_a(obj, os_wxPenList_class))
     return 1;
   else {
@@ -3331,7 +3331,7 @@ class wxPenList *objscheme_unbundle_wxPenList(Scheme_Object *obj, const char *wh
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPenList_class);
   (void)objscheme_istype_wxPenList(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -3600,7 +3600,7 @@ int objscheme_istype_wxCursor(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxCursor_class);
   if (objscheme_is_a(obj, os_wxCursor_class))
     return 1;
   else {
@@ -3644,7 +3644,7 @@ class wxCursor *objscheme_unbundle_wxCursor(Scheme_Object *obj, const char *wher
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxCursor_class);
   (void)objscheme_istype_wxCursor(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -4334,7 +4334,7 @@ int objscheme_istype_wxRegion(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxRegion_class);
   if (objscheme_is_a(obj, os_wxRegion_class))
     return 1;
   else {
@@ -4378,7 +4378,7 @@ class wxRegion *objscheme_unbundle_wxRegion(Scheme_Object *obj, const char *wher
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxRegion_class);
   (void)objscheme_istype_wxRegion(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -4953,7 +4953,7 @@ int objscheme_istype_wxPath(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPath_class);
   if (objscheme_is_a(obj, os_wxPath_class))
     return 1;
   else {
@@ -4997,7 +4997,7 @@ class wxPath *objscheme_unbundle_wxPath(Scheme_Object *obj, const char *where, i
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPath_class);
   (void)objscheme_istype_wxPath(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -5313,7 +5313,7 @@ int objscheme_istype_wxFontNameDirectory(Scheme_Object *obj, const char *stop, i
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxFontNameDirectory_class);
   if (objscheme_is_a(obj, os_wxFontNameDirectory_class))
     return 1;
   else {
@@ -5357,7 +5357,7 @@ class wxFontNameDirectory *objscheme_unbundle_wxFontNameDirectory(Scheme_Object
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxFontNameDirectory_class);
   (void)objscheme_istype_wxFontNameDirectory(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_item.cxx b/src/mred/wxs/wxs_item.cxx
index 9f3581e0da..dae74d1af9 100644
--- a/src/mred/wxs/wxs_item.cxx
+++ b/src/mred/wxs/wxs_item.cxx
@@ -164,7 +164,7 @@ int objscheme_istype_wxItem(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxItem_class);
   if (objscheme_is_a(obj, os_wxItem_class))
     return 1;
   else {
@@ -208,7 +208,7 @@ class wxItem *objscheme_unbundle_wxItem(Scheme_Object *obj, const char *where, i
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxItem_class);
   (void)objscheme_istype_wxItem(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -1027,7 +1027,7 @@ int objscheme_istype_wxMessage(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxMessage_class);
   if (objscheme_is_a(obj, os_wxMessage_class))
     return 1;
   else {
@@ -1071,7 +1071,7 @@ class wxMessage *objscheme_unbundle_wxMessage(Scheme_Object *obj, const char *wh
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxMessage_class);
   (void)objscheme_istype_wxMessage(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_lbox.cxx b/src/mred/wxs/wxs_lbox.cxx
index 930681b1c2..1763247f2f 100644
--- a/src/mred/wxs/wxs_lbox.cxx
+++ b/src/mred/wxs/wxs_lbox.cxx
@@ -1264,7 +1264,7 @@ int objscheme_istype_wxListBox(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxListBox_class);
   if (objscheme_is_a(obj, os_wxListBox_class))
     return 1;
   else {
@@ -1308,7 +1308,7 @@ class wxListBox *objscheme_unbundle_wxListBox(Scheme_Object *obj, const char *wh
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxListBox_class);
   (void)objscheme_istype_wxListBox(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_menu.cxx b/src/mred/wxs/wxs_menu.cxx
index 22029e1e66..47801030de 100644
--- a/src/mred/wxs/wxs_menu.cxx
+++ b/src/mred/wxs/wxs_menu.cxx
@@ -586,7 +586,7 @@ int objscheme_istype_wxMenu(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxMenu_class);
   if (objscheme_is_a(obj, os_wxMenu_class))
     return 1;
   else {
@@ -630,7 +630,7 @@ class wxMenu *objscheme_unbundle_wxMenu(Scheme_Object *obj, const char *where, i
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxMenu_class);
   (void)objscheme_istype_wxMenu(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -899,7 +899,7 @@ int objscheme_istype_wxMenuBar(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxMenuBar_class);
   if (objscheme_is_a(obj, os_wxMenuBar_class))
     return 1;
   else {
@@ -943,7 +943,7 @@ class wxMenuBar *objscheme_unbundle_wxMenuBar(Scheme_Object *obj, const char *wh
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxMenuBar_class);
   (void)objscheme_istype_wxMenuBar(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -1119,7 +1119,7 @@ int objscheme_istype_wxsMenuItem(Scheme_Object *obj, const char *stop, int nullO
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxsMenuItem_class);
   if (objscheme_is_a(obj, os_wxsMenuItem_class))
     return 1;
   else {
@@ -1163,7 +1163,7 @@ class wxsMenuItem *objscheme_unbundle_wxsMenuItem(Scheme_Object *obj, const char
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxsMenuItem_class);
   (void)objscheme_istype_wxsMenuItem(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_misc.cxx b/src/mred/wxs/wxs_misc.cxx
index 95f1f71379..9ad9f425c3 100644
--- a/src/mred/wxs/wxs_misc.cxx
+++ b/src/mred/wxs/wxs_misc.cxx
@@ -268,7 +268,7 @@ int objscheme_istype_wxTimer(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxTimer_class);
   if (objscheme_is_a(obj, os_wxTimer_class))
     return 1;
   else {
@@ -312,7 +312,7 @@ class wxTimer *objscheme_unbundle_wxTimer(Scheme_Object *obj, const char *where,
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxTimer_class);
   (void)objscheme_istype_wxTimer(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -608,7 +608,7 @@ int objscheme_istype_wxClipboard(Scheme_Object *obj, const char *stop, int nullO
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxClipboard_class);
   if (objscheme_is_a(obj, os_wxClipboard_class))
     return 1;
   else {
@@ -652,7 +652,7 @@ class wxClipboard *objscheme_unbundle_wxClipboard(Scheme_Object *obj, const char
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxClipboard_class);
   (void)objscheme_istype_wxClipboard(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -1022,7 +1022,7 @@ int objscheme_istype_wxClipboardClient(Scheme_Object *obj, const char *stop, int
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxClipboardClient_class);
   if (objscheme_is_a(obj, os_wxClipboardClient_class))
     return 1;
   else {
@@ -1066,7 +1066,7 @@ class wxClipboardClient *objscheme_unbundle_wxClipboardClient(Scheme_Object *obj
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxClipboardClient_class);
   (void)objscheme_istype_wxClipboardClient(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -1826,7 +1826,7 @@ int objscheme_istype_wxPrintSetupData(Scheme_Object *obj, const char *stop, int
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPrintSetupData_class);
   if (objscheme_is_a(obj, os_wxPrintSetupData_class))
     return 1;
   else {
@@ -1870,7 +1870,7 @@ class wxPrintSetupData *objscheme_unbundle_wxPrintSetupData(Scheme_Object *obj,
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPrintSetupData_class);
   (void)objscheme_istype_wxPrintSetupData(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_obj.cxx b/src/mred/wxs/wxs_obj.cxx
index 9b1683afe3..8892b107ed 100644
--- a/src/mred/wxs/wxs_obj.cxx
+++ b/src/mred/wxs/wxs_obj.cxx
@@ -120,7 +120,7 @@ int objscheme_istype_wxObject(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxObject_class);
   if (objscheme_is_a(obj, os_wxObject_class))
     return 1;
   else {
@@ -164,7 +164,7 @@ class wxObject *objscheme_unbundle_wxObject(Scheme_Object *obj, const char *wher
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxObject_class);
   (void)objscheme_istype_wxObject(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_panl.cxx b/src/mred/wxs/wxs_panl.cxx
index 74acfb688c..96b6d92572 100644
--- a/src/mred/wxs/wxs_panl.cxx
+++ b/src/mred/wxs/wxs_panl.cxx
@@ -958,7 +958,7 @@ int objscheme_istype_wxPanel(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPanel_class);
   if (objscheme_is_a(obj, os_wxPanel_class))
     return 1;
   else {
@@ -1002,7 +1002,7 @@ class wxPanel *objscheme_unbundle_wxPanel(Scheme_Object *obj, const char *where,
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxPanel_class);
   (void)objscheme_istype_wxPanel(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -1825,7 +1825,7 @@ int objscheme_istype_wxDialogBox(Scheme_Object *obj, const char *stop, int nullO
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxDialogBox_class);
   if (objscheme_is_a(obj, os_wxDialogBox_class))
     return 1;
   else {
@@ -1869,7 +1869,7 @@ class wxDialogBox *objscheme_unbundle_wxDialogBox(Scheme_Object *obj, const char
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxDialogBox_class);
   (void)objscheme_istype_wxDialogBox(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_rado.cxx b/src/mred/wxs/wxs_rado.cxx
index dbc2b4a18d..7dbbaf189c 100644
--- a/src/mred/wxs/wxs_rado.cxx
+++ b/src/mred/wxs/wxs_rado.cxx
@@ -1100,7 +1100,7 @@ int objscheme_istype_wxRadioBox(Scheme_Object *obj, const char *stop, int nullOK
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxRadioBox_class);
   if (objscheme_is_a(obj, os_wxRadioBox_class))
     return 1;
   else {
@@ -1144,7 +1144,7 @@ class wxRadioBox *objscheme_unbundle_wxRadioBox(Scheme_Object *obj, const char *
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxRadioBox_class);
   (void)objscheme_istype_wxRadioBox(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_slid.cxx b/src/mred/wxs/wxs_slid.cxx
index c9a6bc1c14..55c51ae100 100644
--- a/src/mred/wxs/wxs_slid.cxx
+++ b/src/mred/wxs/wxs_slid.cxx
@@ -697,7 +697,7 @@ int objscheme_istype_wxSlider(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxSlider_class);
   if (objscheme_is_a(obj, os_wxSlider_class))
     return 1;
   else {
@@ -741,7 +741,7 @@ class wxSlider *objscheme_unbundle_wxSlider(Scheme_Object *obj, const char *wher
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxSlider_class);
   (void)objscheme_istype_wxSlider(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_tabc.cxx b/src/mred/wxs/wxs_tabc.cxx
index b6e6b94a49..5a48e075c1 100644
--- a/src/mred/wxs/wxs_tabc.cxx
+++ b/src/mred/wxs/wxs_tabc.cxx
@@ -999,7 +999,7 @@ int objscheme_istype_wxTabChoice(Scheme_Object *obj, const char *stop, int nullO
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxTabChoice_class);
   if (objscheme_is_a(obj, os_wxTabChoice_class))
     return 1;
   else {
@@ -1043,7 +1043,7 @@ class wxTabChoice *objscheme_unbundle_wxTabChoice(Scheme_Object *obj, const char
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxTabChoice_class);
   (void)objscheme_istype_wxTabChoice(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
@@ -1626,7 +1626,7 @@ int objscheme_istype_wxGroupBox(Scheme_Object *obj, const char *stop, int nullOK
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxGroupBox_class);
   if (objscheme_is_a(obj, os_wxGroupBox_class))
     return 1;
   else {
@@ -1670,7 +1670,7 @@ class wxGroupBox *objscheme_unbundle_wxGroupBox(Scheme_Object *obj, const char *
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxGroupBox_class);
   (void)objscheme_istype_wxGroupBox(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mred/wxs/wxs_win.cxx b/src/mred/wxs/wxs_win.cxx
index cbebda495f..0a84d26456 100644
--- a/src/mred/wxs/wxs_win.cxx
+++ b/src/mred/wxs/wxs_win.cxx
@@ -1418,7 +1418,7 @@ int objscheme_istype_wxWindow(Scheme_Object *obj, const char *stop, int nullOK)
 {
   REMEMBER_VAR_STACK();
   if (nullOK && XC_SCHEME_NULLP(obj)) return 1;
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxWindow_class);
   if (objscheme_is_a(obj, os_wxWindow_class))
     return 1;
   else {
@@ -1462,7 +1462,7 @@ class wxWindow *objscheme_unbundle_wxWindow(Scheme_Object *obj, const char *wher
 
   REMEMBER_VAR_STACK();
 
-  obj = objscheme_unwrap(obj);
+  obj = objscheme_unwrap(obj, os_wxWindow_class);
   (void)objscheme_istype_wxWindow(obj, where, nullOK);
   Scheme_Class_Object *o = (Scheme_Class_Object *)obj;
   WITH_REMEMBERED_STACK(objscheme_check_valid(NULL, NULL, 0, &obj));
diff --git a/src/mzscheme/utils/xcglue.c b/src/mzscheme/utils/xcglue.c
index 48363cccf3..b7c74646d5 100644
--- a/src/mzscheme/utils/xcglue.c
+++ b/src/mzscheme/utils/xcglue.c
@@ -91,6 +91,7 @@ typedef struct Scheme_Class {
   Scheme_Object **methods;
   Scheme_Object *base_struct_type;
   Scheme_Object *struct_type;
+  Scheme_Object *unwrap_property;
 } Scheme_Class;
 
 Scheme_Type objscheme_class_type;
@@ -99,7 +100,6 @@ static Scheme_Object *object_struct;
 static Scheme_Object *object_property;
 static Scheme_Object *dispatcher_property;
 static Scheme_Object *preparer_property;
-static Scheme_Object *unwrapper_property;
 
 #ifdef MZ_PRECISE_GC
 # include "../gc2/gc2.h"
@@ -122,6 +122,7 @@ int gc_class_mark(void *_c)
   gcMARK(c->methods);
   gcMARK(c->base_struct_type);
   gcMARK(c->struct_type);
+  gcMARK(c->unwrap_property);
   
   return gcBYTES_TO_WORDS(sizeof(Scheme_Class));
 }
@@ -137,6 +138,7 @@ int gc_class_fixup(void *_c)
   gcFIXUP(c->methods);
   gcFIXUP(c->base_struct_type);
   gcFIXUP(c->struct_type);
+  gcFIXUP(c->unwrap_property);
   
   return gcBYTES_TO_WORDS(sizeof(Scheme_Class));
 }
@@ -174,9 +176,11 @@ static Scheme_Object *class_prepare_struct_type(int argc, Scheme_Object **argv)
     scheme_wrong_type("primitive-class-prepare-struct-type!", "struct-type-property", 1, argc, argv);
   scheme_check_proc_arity("primitive-class-prepare-struct-type!", 1, 3, argc, argv);
   scheme_check_proc_arity("primitive-class-prepare-struct-type!", 2, 4, argc, argv);
-  scheme_check_proc_arity("primitive-class-prepare-struct-type!", 1, 5, argc, argv);
+  if(SCHEME_TYPE(argv[5]) != scheme_struct_property_type)
+    scheme_wrong_type("primitive-class-prepare-struct-type!", "struct-type-property", 5, argc, argv);
+  scheme_check_proc_arity("primitive-class-prepare-struct-type!", 1, 6, argc, argv);
 
-  props = argv[6];
+  props = argv[7];
   while (SCHEME_PAIRP(props)) {
     name = SCHEME_CAR(props);
     if (!SCHEME_PAIRP(name))
@@ -186,8 +190,8 @@ static Scheme_Object *class_prepare_struct_type(int argc, Scheme_Object **argv)
     props = SCHEME_CDR(props);
   }
   if (!SCHEME_NULLP(props))
-    scheme_wrong_type("primitive-class-prepare-struct-type!", "list of struct-type-property--value pairs", 6, argc, argv);
-  props = argv[6];
+    scheme_wrong_type("primitive-class-prepare-struct-type!", "list of struct-type-property--value pairs", 7, argc, argv);
+  props = argv[7];
 
   objscheme_something_prepared = 1;
 
@@ -238,7 +242,8 @@ static Scheme_Object *class_prepare_struct_type(int argc, Scheme_Object **argv)
   
   /* Type to derive/instantiate from Scheme: */
 
-  props = scheme_make_pair(scheme_make_pair(unwrapper_property, argv[5]), props);
+  c->unwrap_property = argv[5];
+  props = scheme_make_pair(scheme_make_pair(argv[5], argv[6]), props);
   props = scheme_make_pair(scheme_make_pair(dispatcher_property, argv[4]), props);
 
   props = scheme_make_pair(scheme_make_pair(preparer_property, argv[3]), props);
@@ -457,14 +462,18 @@ int objscheme_is_a(Scheme_Object *o, Scheme_Object *c)
   return !!a;
 }
 
-Scheme_Object *objscheme_unwrap(Scheme_Object *obj)
+Scheme_Object *objscheme_unwrap(Scheme_Object *obj, Scheme_Object *c)
 {
-  Scheme_Object *s[1], *unwrapper;
+  Scheme_Object *s[1], *unwrapper, *unwrap_prop;
+  Scheme_Class *cls = (Scheme_Class *)cls;
 
   if (!obj)
     return NULL;
 
-  unwrapper = scheme_struct_type_property_ref(unwrapper_property, (Scheme_Object *)obj);
+  unwrap_prop = cls->unwrap_property;
+  if(!unwrap_prop)
+    return obj;
+  unwrapper = scheme_struct_type_property_ref(unwrap_prop, (Scheme_Object *)obj);
   if (!unwrapper)
     return obj;
 
@@ -540,9 +549,6 @@ void objscheme_init(Scheme_Env *env)
   wxREGGLOB(dispatcher_property);
   dispatcher_property = scheme_make_struct_type_property(scheme_intern_symbol("primitive-dispatcher"));
 
-  wxREGGLOB(unwrapper_property);
-  unwrapper_property = scheme_make_struct_type_property(scheme_intern_symbol("primitive-unwrapper"));
-
   wxREGGLOB(object_struct);
   object_struct = scheme_make_struct_type(scheme_intern_symbol("primitive-object"), 
 					  NULL, NULL,
@@ -562,7 +568,7 @@ void objscheme_init(Scheme_Env *env)
   scheme_install_xc_global("primitive-class-prepare-struct-type!",
 			   scheme_make_prim_w_arity(class_prepare_struct_type,
 						    "primitive-class-prepare-struct-type!",
-						    7, 7),
+						    8, 8),
 			   env);
   
   scheme_install_xc_global("primitive-class-find-method",
diff --git a/src/mzscheme/utils/xcglue.h b/src/mzscheme/utils/xcglue.h
index aa9631ce59..ef5f496ab9 100644
--- a/src/mzscheme/utils/xcglue.h
+++ b/src/mzscheme/utils/xcglue.h
@@ -78,7 +78,7 @@ Scheme_Object *objscheme_find_method(Scheme_Object *obj,
 int objscheme_is_subclass(Scheme_Object *a, Scheme_Object *sup);
 int objscheme_is_a(Scheme_Object *o, Scheme_Object *c);
 
-Scheme_Object *objscheme_unwrap(Scheme_Object *);
+Scheme_Object *objscheme_unwrap(Scheme_Object *, Scheme_Object *);
 
 Scheme_Object *objscheme_unbox(Scheme_Object *, const char *where);
 Scheme_Object *objscheme_nullable_unbox(Scheme_Object *, const char *where);
diff --git a/src/mzscheme/utils/xctocc b/src/mzscheme/utils/xctocc
index e6d5c7b2f0..e7245e8971 100755
--- a/src/mzscheme/utils/xctocc
+++ b/src/mzscheme/utils/xctocc
@@ -1237,7 +1237,7 @@ sub DoPrintClass
 	print "{\n";
 	print "  REMEMBER_VAR_STACK();\n";
 	print "  if (nullOK && XC_SCHEME_NULLP(obj)) return 1;\n";
-	print "  obj = objscheme_unwrap(obj);\n";
+	print "  obj = objscheme_unwrap(obj, ${newclass}_class);\n";
 	print "  if (objscheme_is_a(obj, ${newclass}_class))\n";
 	print "    return 1;\n";
 	print "  else {\n";
@@ -1288,7 +1288,7 @@ sub DoPrintClass
 	print "{\n";
 	print "  if (nullOK && XC_SCHEME_NULLP(obj)) return NULL;\n\n";
 	print "  REMEMBER_VAR_STACK();\n\n";
-	print "  obj = objscheme_unwrap(obj);\n";
+	print "  obj = objscheme_unwrap(obj, ${newclass}_class);\n";
 	print "  (void)objscheme_istype_${oldclass}(obj, where, nullOK);\n";
 
 	print "  Scheme_Class_Object *o = ";