Poco StreamConverter produces C4250 warning

When compiling of 0.8.4 in VS2012, the 11.0 compiler produce the C4250 warning.
Described in this link: https://connect.microsoft.com/VisualStudio/feedback/details/733720/

Solution:
Modify the StreamConverter.h.

Add this 2 mocks, in the InputStreamConverter and OutputStreamConverter:

class Foundation_API InputStreamConverter: public StreamConverterIOS, public std::istream
{
public:
InputStreamConverter(std::istream& istr, const TextEncoding& inEncoding, const TextEncoding& outEncoding, int defaultChar = ‘?’);
void _Add_vtordisp1() { } // Required to avoid VC++ warning C4250
void _Add_vtordisp2() { } // Required to avoid VC++ warning C4250
~InputStreamConverter();
};

class Foundation_API OutputStreamConverter: public StreamConverterIOS, public std::ostream
{
public:
OutputStreamConverter(std::ostream& ostr, const TextEncoding& inEncoding, const TextEncoding& outEncoding, int defaultChar = ‘?’);
void _Add_vtordisp1() { } // Required to avoid VC++ warning C4250
void _Add_vtordisp2() { } // Required to avoid VC++ warning C4250
~OutputStreamConverter();
};

Hello Marcio,

I am also on of 0.8.4, vs2012 and v110 compiler. I modified my StreamConverter.h as you suggest but I still have those warnings.
Nothing else to modify to clear warnings ?