C-style cast suceeds whereas static_cast reports error

[NMTop40]

I may be missing something, but why do you even need a cast? CWindow is a derived class of CApplicationCallback so you don't need a cast to assign a derived pointer to a base pointer.

Yes you missed something. His inheritance is private.

Try making the inheritance public thus:

class CWindow : public CApplicationCallback
{
// etc.
};