LRESULT CALLBACK WndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch (uMsg)
    {
        // Creation of the Win32 Window
        case WM_CREATE:
            // Add an Edit Field
            CreateWindowEx(
                WS_EX_CLIENTEDGE,
                "EDIT",
                "",
                WS_CHILD | WS_VISIBLE,
                5, 5, 200, 24,
                hwnd,
                (HMENU)100,
                g_Instance, // Comming from WinMain
                NULL
            );
            return DefWindowProc(hwnd, uMsg, lParam, wParam);
        case WM_KEYDOWN:
            // Track key presses on the edit field
            std::cout << "The key with the code " << wParam << " was pressed." << std::endl;
            return 0;
        case WM_PAINT:
            // Some painting code...
            return DefWindowProc(hwnd, uMsg, lParam, wParam);
        default:
            return DefWindowProc(hwnd, uMsg, lParam, wParam);
    }
}

OldWndProc = (WNDPROC)SetWindowLongPtr (hButton, GWLP_WNDPROC, (LONG_PTR)NewWndProc);

case WM_COMMAND:

      if(wParam=IDOFDEFBUTTON || IDOK) ...

if(!IsDialogMessage(hWnd,&msg)) {
    TranslateMessage(&msg);
    DispatchMessage(&msg);
 }