Your main.cpp file contains only code for creating a standard window and some child windows with what is essentially an unregistered class(unregistered since that code is never called). The system will only create windows of registered 'window classes'(those registered with RegisterClassEx) and, since you never actually invoke any code to do so in the WM_CREATE handler in main.cpp, window creation will fail.
Instantiate an object of your c++ class and invoke its methods to register and create windows of your own 'window classes' in your test source file(main.cpp).
