don't define WINVER as 0x0600 for VC6, its standard headers warn against this if we do

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@34599 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/wrapwin.h

@@ -13,23 +13,36 @@
 
 #include "wx/platform.h"
 
+// strict type checking to detect conversion from HFOO to HBAR at compile-time
 #ifndef STRICT
     #define STRICT 1
 #endif
 
-// don't define min() and max() as macros, they conflict with standard C++ ones
+// this macro tells windows.h to not define min() and max() as macros: we need
+// this as otherwise they conflict with standard C++ functions
 #ifndef NOMINMAX
     #define NOMINMAX
 #endif // NOMINMAX
 
+
 // before including windows.h, define version macros at (currently) maximal
 // values because we do all our checks at run-time anyhow
+#ifndef WINVER
+    // the only exception to the above is MSVC 6 which has a time bomb in its
+    // headers: they warn against using them with WINVER >= 0x0500 as they
+    // contain only part of the declarations and they're not always correct, so
+    // don't define WINVER for it at all as this allows everything to work as
+    // expected both with standard VC6 headers (which define WINVER as 0x0400
+    // by default) and headers from a newer SDK (which may define it as 0x0500)
+    #if !defined(__VISUALC__) || (__VISUALC__ >= 1300)
+        #define WINVER 0x0600
+    #endif
+#endif
+
 #ifndef _WIN32_WINNT
     #define _WIN32_WINNT 0x0600
 #endif
-#ifndef WINVER
-    #define WINVER 0x0600
-#endif
+
 
 #include <windows.h>
 
@@ -46,8 +59,11 @@
     #include <shellapi.h>
 #endif // __WXWINCE__
 
+
+// #undef the macros defined in winsows.h which conflict with code elsewhere
 #include "wx/msw/winundef.h"
 
+
 // types DWORD_PTR, ULONG_PTR and so on might be not defined in old headers but
 // unfortunately I don't know of any standard way to test for this (as they're
 // typedefs and not #defines), so simply overwrite them in any case in Win32