diff --git a/src/mred/wxs/wxs_win.cxx b/src/mred/wxs/wxs_win.cxx
index 900b456e8d..3df067381a 100644
--- a/src/mred/wxs/wxs_win.cxx
+++ b/src/mred/wxs/wxs_win.cxx
@@ -113,6 +113,15 @@ static long wxWindowGetHandle(wxWindow *w)
 #endif
 }
 
+static void CenterWParent(wxWindow *w, int direction, wxWindow *parent)
+{
+#ifdef wx_mac
+  w->Centre(direction, parent);
+#else
+  w->Centre(direction);
+#endif
+}
+
 static Scheme_Object *sizeMode_wxSIZE_AUTO_sym = NULL;
 static Scheme_Object *sizeMode_wxSIZE_USE_EXISTING_sym = NULL;
 static Scheme_Object *sizeMode_wxPOS_USE_MINUS_ONE_sym = NULL;
@@ -803,24 +812,30 @@ static Scheme_Object *os_wxWindowPopupMenu(int n,  Scheme_Object *p[])
   return scheme_void;
 }
 
-static Scheme_Object *os_wxWindowCenter(int n,  Scheme_Object *p[])
+static Scheme_Object *os_wxWindowCenterWParent(int n,  Scheme_Object *p[])
 {
   WXS_USE_ARGUMENT(n) WXS_USE_ARGUMENT(p)
   REMEMBER_VAR_STACK();
   objscheme_check_valid(os_wxWindow_class, "center in window%", n, p);
   int x0;
+  class wxWindow* x1 INIT_NULLED_OUT;
 
-  SETUP_VAR_STACK_REMEMBERED(1);
+  SETUP_VAR_STACK_REMEMBERED(2);
   VAR_STACK_PUSH(0, p);
+  VAR_STACK_PUSH(1, x1);
 
   
   if (n > (POFFSET+0)) {
     x0 = WITH_VAR_STACK(unbundle_symset_direction(p[POFFSET+0], "center in window%"));
   } else
     x0 = wxBOTH;
+  if (n > (POFFSET+1)) {
+    x1 = WITH_VAR_STACK(objscheme_unbundle_wxWindow(p[POFFSET+1], "center in window%", 1));
+  } else
+    x1 = NULL;
 
   
-  WITH_VAR_STACK(((wxWindow *)((Scheme_Class_Object *)p[0])->primdata)->Center(x0));
+  WITH_VAR_STACK(CenterWParent(((wxWindow *)((Scheme_Class_Object *)p[0])->primdata), x0, x1));
 
   
   
@@ -1369,7 +1384,7 @@ void objscheme_setup_wxWindow(Scheme_Env *env)
   WITH_VAR_STACK(scheme_add_method_w_arity(os_wxWindow_class, "get-width" " method", (Scheme_Method_Prim *)os_wxWindowwxSchemeWindowGetWidth, 0, 0));
   WITH_VAR_STACK(scheme_add_method_w_arity(os_wxWindow_class, "get-height" " method", (Scheme_Method_Prim *)os_wxWindowwxSchemeWindowGetHeight, 0, 0));
   WITH_VAR_STACK(scheme_add_method_w_arity(os_wxWindow_class, "popup-menu" " method", (Scheme_Method_Prim *)os_wxWindowPopupMenu, 3, 3));
-  WITH_VAR_STACK(scheme_add_method_w_arity(os_wxWindow_class, "center" " method", (Scheme_Method_Prim *)os_wxWindowCenter, 0, 1));
+  WITH_VAR_STACK(scheme_add_method_w_arity(os_wxWindow_class, "center" " method", (Scheme_Method_Prim *)os_wxWindowCenterWParent, 0, 2));
   WITH_VAR_STACK(scheme_add_method_w_arity(os_wxWindow_class, "get-text-extent" " method", (Scheme_Method_Prim *)os_wxWindowGetTextExtent, 3, 7));
   WITH_VAR_STACK(scheme_add_method_w_arity(os_wxWindow_class, "get-parent" " method", (Scheme_Method_Prim *)os_wxWindowGetParent, 0, 0));
   WITH_VAR_STACK(scheme_add_method_w_arity(os_wxWindow_class, "refresh" " method", (Scheme_Method_Prim *)os_wxWindowRefresh, 0, 0));
diff --git a/src/mred/wxs/wxs_win.h b/src/mred/wxs/wxs_win.h
index 362223f787..cdeebf0d69 100644
--- a/src/mred/wxs/wxs_win.h
+++ b/src/mred/wxs/wxs_win.h
@@ -8,6 +8,7 @@ extern class wxMouseEvent *objscheme_unbundle_wxMouseEvent(Scheme_Object *, cons
 extern class wxWindow *objscheme_unbundle_wxWindow(Scheme_Object *, const char *, int);
 extern class wxKeyEvent *objscheme_unbundle_wxKeyEvent(Scheme_Object *, const char *, int);
 extern class wxMenu *objscheme_unbundle_wxMenu(Scheme_Object *, const char *, int);
+extern class wxWindow *objscheme_unbundle_wxWindow(Scheme_Object *, const char *, int);
 extern class wxFont *objscheme_unbundle_wxFont(Scheme_Object *, const char *, int);
 extern Scheme_Object *objscheme_bundle_wxWindow(class wxWindow *);
 extern class wxCursor *objscheme_unbundle_wxCursor(Scheme_Object *, const char *, int);
diff --git a/src/mred/wxs/wxs_win.xc b/src/mred/wxs/wxs_win.xc
index 02015e998d..73e86d7af7 100644
--- a/src/mred/wxs/wxs_win.xc
+++ b/src/mred/wxs/wxs_win.xc
@@ -87,6 +87,15 @@ static long wxWindowGetHandle(wxWindow *w)
 #endif
 }
 
+static void CenterWParent(wxWindow *w, int direction, wxWindow *parent)
+{
+#ifdef wx_mac
+  w->Centre(direction, parent);
+#else
+  w->Centre(direction);
+#endif
+}
+
 @BEGINSYMBOLS sizeMode > ONE > PRED BUNDLE
 @SYM "auto" : wxSIZE_AUTO
 @SYM "use-exsiting" : wxSIZE_USE_EXISTING
@@ -128,7 +137,7 @@ static long wxWindowGetHandle(wxWindow *w)
 @ "refresh" : void Refresh();
 @ "get-parent" : wxWindow^ GetParent();
 @ "get-text-extent" : void GetTextExtent(string,double*,double*,double?=NULL,double?=NULL,wxFont^=NULL,bool=FALSE);
-@ "center" : void Center(SYM[direction]=wxBOTH);
+@ m "center" : void CenterWParent(SYM[direction]=wxBOTH, wxWindow^=NULL);
 
 @ "popup-menu" : void PopupMenu(wxMenu!, rint[0|10000], rint[0|10000]);
 
diff --git a/src/wxmac/include/base/wb_dialg.h b/src/wxmac/include/base/wb_dialg.h
index f6772878ad..122b615352 100644
--- a/src/wxmac/include/base/wb_dialg.h
+++ b/src/wxmac/include/base/wb_dialg.h
@@ -38,7 +38,7 @@ class wxbDialogBox: public wxFrame
   virtual void Iconize(Bool iconize) = 0;
   virtual Bool Iconized(void) = 0;
 
-  void Centre(int direction = wxBOTH);
+  void Centre(int direction = wxBOTH, wxWindow *parent = NULL);
 };
 
 #define wxOPEN 1
diff --git a/src/wxmac/include/base/wb_frame.h b/src/wxmac/include/base/wb_frame.h
index 8330b1823f..6114d5cdd0 100644
--- a/src/wxmac/include/base/wb_frame.h
+++ b/src/wxmac/include/base/wb_frame.h
@@ -75,7 +75,7 @@ class wxbFrame: public wxWindow
   virtual void SetStatusText(char *text, int number = 0) = 0;
   virtual Bool StatusLineExists(void);
 
-  void Centre(int direction = wxBOTH);
+  void Centre(int direction = wxBOTH, wxWindow *parent = NULL);
 
   // Iconize
   virtual void Iconize(Bool iconize) = 0;
diff --git a/src/wxmac/include/base/wb_item.h b/src/wxmac/include/base/wb_item.h
index a5443c8412..1787d85941 100644
--- a/src/wxmac/include/base/wb_item.h
+++ b/src/wxmac/include/base/wb_item.h
@@ -48,7 +48,7 @@ class wxbItem: public wxWindow
    virtual void ProcessCommand(wxCommandEvent *event); // Calls the callback and 
 
   // Places item in centre of panel - so can't be used BEFORE panel->Fit()
-  void Centre(int direction = wxHORIZONTAL);
+   void Centre(int direction = wxHORIZONTAL, wxWindow *p = NULL);
 };
 
 #endif // IN_CPROTO
diff --git a/src/wxmac/include/base/wb_win.h b/src/wxmac/include/base/wb_win.h
index cabce41ba3..3605c244d5 100644
--- a/src/wxmac/include/base/wb_win.h
+++ b/src/wxmac/include/base/wb_win.h
@@ -126,13 +126,10 @@ class wxbWindow: public wxObject
   virtual void SetName(char *name);
 
   inline virtual void Fit(void) {};                  // Size window to fit contents
-  inline virtual void Centre(int direction) {};      // Centre item on panel,
-                                               // or frame on screen
+  inline virtual void Centre(int direction = wxBOTH, wxWindow *parent = NULL) {};
   // Renamed from GetWindowStyle since it clashed with a
   // macro in windowsx.h.
   inline long GetWindowStyleFlag(void) { return windowStyle; }
-  // A concession to our friends across the pond
-  inline void Center(int direction = wxHORIZONTAL) { Centre(direction); }
 
   inline virtual void EnablePainting(Bool enable) { paintingEnabled = enable; }
 
diff --git a/src/wxmac/include/mac/wx_dialg.h b/src/wxmac/include/mac/wx_dialg.h
index bf34dfcd07..6d83ca510c 100644
--- a/src/wxmac/include/mac/wx_dialg.h
+++ b/src/wxmac/include/mac/wx_dialg.h
@@ -65,7 +65,7 @@ public:
 	Bool OnClose(void);
 
 	virtual void Fit(void);
-	virtual void Centre(int d) { cFrame->Centre(d); }
+	virtual void Centre(int d = wxBOTH, wxWindow *p = NULL) { cFrame->Centre(d, p); }
 
 	void SetIcon(wxBitmap* icon) { cFrame->SetIcon(icon); }
 	void Iconize(Bool iconize) { cFrame->Iconize(iconize); }
diff --git a/src/wxmac/include/mac/wx_panel.h b/src/wxmac/include/mac/wx_panel.h
index c31469c9bb..2e8a1cbffe 100644
--- a/src/wxmac/include/mac/wx_panel.h
+++ b/src/wxmac/include/mac/wx_panel.h
@@ -116,7 +116,7 @@ public:
 	// Sizing methods
 	//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 	void DoSetSize(int x, int y, int width, int height);
-        void Centre(int direction);
+        void Centre(int direction = wxBOTH, wxWindow *p = NULL);
 	void Fit(void);
 
 	//+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
diff --git a/src/wxmac/src/base/wb_dialg.cc b/src/wxmac/src/base/wb_dialg.cc
index 9afaeaa350..882eaf0b95 100644
--- a/src/wxmac/src/base/wb_dialg.cc
+++ b/src/wxmac/src/base/wb_dialg.cc
@@ -84,8 +84,8 @@ wxbDialogBox::~wxbDialogBox()
   tlw->DeleteObject(this);
 }
 
-void wxbDialogBox::Centre(int direction)
+void wxbDialogBox::Centre(int direction, wxWindow *p)
 {
-  ((wxDialogBox *)this)->cFrame->Centre(direction);
+  ((wxDialogBox *)this)->cFrame->Centre(direction, p);
 }
 
diff --git a/src/wxmac/src/base/wb_frame.cc b/src/wxmac/src/base/wb_frame.cc
index 2f5ee9ac78..5b48c66421 100644
--- a/src/wxmac/src/base/wb_frame.cc
+++ b/src/wxmac/src/base/wb_frame.cc
@@ -133,20 +133,27 @@ Bool wxbFrame::StatusLineExists(void)
   return status_line_exists;
 }
 
-void wxbFrame::Centre(int direction)
+void wxbFrame::Centre(int direction, wxWindow *parent)
 {
-  int display_width, display_height, width, height, x, y;
-  wxDisplaySize(&display_width, &display_height);
+  int display_width, display_height, width, height, x, y, offset_x, offset_y;
+
+  if (parent) {
+    parent->GetSize(&display_width, &display_height);
+    parent->GetPosition(&offset_x, &offset_y);
+  } else {
+    wxDisplaySize(&display_width, &display_height);
+    offset_x = offset_y = 0;
+  }
 
   GetSize(&width, &height);
   GetPosition(&x, &y);
-
+  
   if (direction & wxHORIZONTAL)
     x = (int)((display_width - width)/2);
   if (direction & wxVERTICAL)
     y = (int)((display_height - height)/2);
-
-  SetSize(x, y, width, height, wxPOS_USE_MINUS_ONE);
+  
+  SetSize(x + offset_x, y + offset_y, width, height, wxPOS_USE_MINUS_ONE);
 }
 
 // Call this to simulate a menu command
diff --git a/src/wxmac/src/base/wb_item.cc b/src/wxmac/src/base/wb_item.cc
index 9acdfc88dc..8075d80941 100644
--- a/src/wxmac/src/base/wb_item.cc
+++ b/src/wxmac/src/base/wb_item.cc
@@ -170,7 +170,7 @@ wxbItem::~wxbItem (void)
   }
 }
 
-void wxbItem::Centre (int direction)
+void wxbItem::Centre (int direction, wxWindow *)
 {
   int x, y, width, height, panel_width, panel_height, new_x, new_y;
   wxPanel *panel;
diff --git a/src/wxmac/src/mac/wx_dialg.cc b/src/wxmac/src/mac/wx_dialg.cc
index b38f413d9b..0a6e5bafe2 100644
--- a/src/wxmac/src/mac/wx_dialg.cc
+++ b/src/wxmac/src/mac/wx_dialg.cc
@@ -180,7 +180,7 @@ static wxFrame *make_dlog_frame(wxWindow *parentFrame, char *windowTitle, int x,
 //-----------------------------------------------------------------------------
 wxDialogBox::wxDialogBox // Constructor (for dialog window)
 (
- wxWindow*	parentFrame,		// this is ignored, used to be wxFrame*
+ wxWindow*	parentFrame,
  char*		windowTitle,
  Bool		modal,
  int 		x,
diff --git a/src/wxmac/src/mac/wx_frame.cc b/src/wxmac/src/mac/wx_frame.cc
index 44a451577b..2a796e2367 100644
--- a/src/wxmac/src/mac/wx_frame.cc
+++ b/src/wxmac/src/mac/wx_frame.cc
@@ -60,7 +60,7 @@ static ControlUserPaneDrawUPP userPaneDrawFunctionUPP = NewControlUserPaneDrawUP
 //-----------------------------------------------------------------------------
 wxFrame::wxFrame // Constructor (for frame window)
 (
- wxFrame*	parentFrame,		// this is ignored
+ wxFrame*	parentFrame,
  char*		windowTitle,
  int 		x,
  int			y,
diff --git a/src/wxmac/src/mac/wx_panel.cc b/src/wxmac/src/mac/wx_panel.cc
index faeb5444ea..9ce6bc575c 100644
--- a/src/wxmac/src/mac/wx_panel.cc
+++ b/src/wxmac/src/mac/wx_panel.cc
@@ -264,7 +264,7 @@ void wxPanel::DoSetSize(int x, int y, int width, int height)
 
 
 //-----------------------------------------------------------------------------
-void wxPanel::Centre(int direction)
+void wxPanel::Centre(int direction, wxWindow *)
 {
   int width, height, panel_width, panel_height, new_x, new_y;
   wxPanel* father;