error C2248

We maybe meet a this error when using class that derived from CWnd or CObject class.
MFC class , CObject prevent using copy constructor and assignment operator.
Because It's can make an abnormal behavior .
To resolve this error we should override copy constructor and assignment operator.

class CTestWindow : public Cwnd
{
public:
CTestWindow();
virtual ~CTestWindow();
CTestWindow( const CTestWindow &s )
{ *this = s; }
CTestWindow& operator=( const CTestWindow &s )
{ return *this; }
};

Also see following KB article.
http://support.microsoft.com/kb/117794