diff --git a/include/wx/wx_cw_cm.h b/include/wx/wx_cw_cm.h
index 760742f751..c5dd9aef7a 100644
--- a/include/wx/wx_cw_cm.h
+++ b/include/wx/wx_cw_cm.h
@@ -40,15 +40,16 @@
     #endif
     #endif
 #elif defined( __WXMAC__)
-	  #define	USE_PRECOMPILED_MAC_HEADERS	0  /*Set to 0 if you don't want to use precompiled MacHeaders*/
-	  #define ACCESSOR_CALLS_ARE_FUNCTIONS 1
-	  #ifdef __WXDEBUG__
-	  // otherwise the debugger looses all symbol information
-    #define OPAQUE_TOOLBOX_STRUCTS 0
-	  #else
-    #define OPAQUE_TOOLBOX_STRUCTS 1
+    #define	USE_PRECOMPILED_MAC_HEADERS	0  /*Set to 0 if you don't want to use precompiled MacHeaders*/
+    #define ACCESSOR_CALLS_ARE_FUNCTIONS 1
+    #ifdef __WXDEBUG__
+        // otherwise the debugger looses all symbol information
+        #define OPAQUE_TOOLBOX_STRUCTS 0
+    // #else
+        // enabling opaque toolbox structs under Classic will break access to contrlDefProc (control.cpp)
+        // #define OPAQUE_TOOLBOX_STRUCTS 1
     #endif
-      #include <ansi_prefix.mac.h>
+    #include <ansi_prefix.mac.h>
       /*
       #include <MacTypes.h>
 		#if UNIVERSAL_INTERFACES_VERSION < 0x0340