Linker cannot find CFrameWnd::_GetBaseMessageMap

Hello newsgroup,

I'm experiencing a quite strange phenomenon: I have a class derived from
CFrameWnd inside a static library (the following code shows the definition of
the template version; in my code I use CFrameWnd for t_BaseFrameClass). The
reason why I want to use the template is that I want to be able to use the
CHelperMixin class for MDI and SDI projects.

[The following code depends on MFC 4.2. Also you'll have to define _AFXDLL in
order to compile it]

template<class t_BaseFrameClass>
class CHelperMixin: public t_BaseFrameClass
{
   typedef t_BaseFrameClass TBaseFrameClass;
protected:
#ifdef _AFXDLL
protected: \
   static const AFX_MSGMAP* PASCAL _GetBaseMessageMap();
#endif
protected:
   virtual const AFX_MSGMAP* GetMessageMap() const;
};

The follwing code provides the implementation of above message map related methods.

template<class t_BaseFrameClass>
inline const AFX_MSGMAP* PASCAL
CHelperMixin<t_BaseFrameClass>::_GetBaseMessageMap ()
{
   return &TBaseFrameClass::messageMap;
}

template<class t_BaseFrameClass>
inline const AFX_MSGMAP* CHelperMixin<t_BaseFrameClass>::GetMessageMap() const
{
   // Define an empty message map (just for demonstration).
   static const AFX_MSGMAP_ENTRY messageEntries[] =
   {
   END_MESSAGE_MAP()

   static const AFX_MSGMAP messageMap =
   {
     TBaseFrameClass::_GetBaseMessageMap,
     &messageEntries[0]
   };
   return &messageMap;
}

I use the code like this:

class CMyMainFrame : public CHelperMixin<CFrameWnd>
{
};

Everything compiles fine, but I get a linker error:
error LNK2001: Unresolved external
"protected: static struct AFX_MSGMAP const * __stdcall
CFrameWnd::_GetBaseMessageMap(void)"

Strange enough, if I provide this method in one of my source files, everything
seems to be OK. I wonder how this could happen. Shouldn't the linker complain
about multiple definitions of this method? Surely this method is part of the
static libraries of MFC!

Thanks in advance,
Stuart