SubClassing

SubClassing Window Handle= hwnd;
SubClassing Destination Message Procedure= newWndProc;

1. hwnd가 생성된 후,
oldWndProc=
    (WNDPROC)SetWindowLong(hwnd, GWL_WNDPROC, (LONG)newWndProc);

2. 종료할 때,
SetWindowLong(hwnd, GWL_WNDPROC, (LONG)oldWndProc);

3. SubClassing Window Procedure
LRESULT CALLBACK
newWndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam){


    return CallWindowProc(oldWndProc, hWnd, msg, wParam, lParam);
}