a callback function across the dll boundary

Hi,

I have two classes CMain and CSupport that are located in two different
dlls, main.dll and support.dll, respectively. main.dll depends on
support.dll. I want that CMain gets notified during CSupport's
destruction (it's CSupport rather than CMain that knows when CSupport
needs to be destructed). We can use MFC's message notification
mechanism. But would it be possible to simply pass a function in CMain
to CSupport as a callback routine? Can callback functions go across the
dll boundary? The following code illustrates what I want, but it must
have syntax errors. Can someone correct the syntax? Any help is much
appreciated.

// ******************
In main.dll:

class CMain
{
   ..
   void CallBackFunc(int nRet);
};

CMain m;
...
CSupport *m_pSupport = new CSupport(m.CallBackFunc());

// ******************
In support.dll

#ifdef SUPPORTDLL
#define CLASS_DECL _declspec( dllexport )
#else
#define CLASS_DECL _declspec( dllimport )
#endif

typedef void(*funcptr)(int);
class CLASS_DECL CSupport
{
   CSupport(funcptr *p)
   {
     m_p = p;
   }

   ~CSupport()
   {
     if (m_p)
       m_p(3); // return code is 3
   }

   funcptr m_p;
};

JD