C / C++ / MFC

class MyClass : public CWnd
{  
    HWND m_hWnd;

public:
    static LRESULT MyHandler(HWND hWnd, UINT nMsg, WPARAM wParam, LPARAM lParam) 
    {
        LRESULT lResult;
        MyClass *ThisPtr = dynamic_cast<MyClass*>(::GetWindowLong(hWnd, GWL_USERDATA));
        if (!ThisPtr)
        {
            //Call defwindow proc, this window has not been initialized for this class.
        }

        switch (nMsg)
        {
            case WM_CREATE:
            {
                 lResult = ThisPtr->OnCreate(nMsg, wParam, lParam);
                 ...
            }
            case ...:
            ...
        }

        return lResult;
    }  

    HWND CreateWindow()  
    {     
        WNDCLASS wc;    
        wc.lpfnWndProc = MyHandler;    
        m_hWnd = CreateWindow(blah);  

        ::SetWindowLong(m_hWnd, GWL_USERDATA, (LONG)this);
        
        return m_hWnd;
    }

    // Handler functions
    LRESULT OnCreate (WPARAM wParam, LPARAM lParam)
    {
         //Handle the WM_CREATE message.
    }
};

for(int i = 0; i < objectOutput.size(); i++)     
     outfile  << setiosflags( std::ios::hex) << objectOutput[i] << std::endl;

VERIFY(m_wndTree.SetCheck(hSel, TRUE));
m_wndTree.Invalidate();