// untested code.....void SubClassControl(HWND ctrl, WNDPROC custom){  WNDPROC original = SetWindowLong(ctrl,GWL_WNDPROC,(LONG)custom);  // need to store a copy of the original somewhere so we can   // get at it later... use the user defined space for the control...  SetWindowLong(ctrl,GWL_USERDATA,(LONG)original);}// also need to call this function at the end of your custom WndProcBOOL OriginalWndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam){  // retrieve the original window proc from the user defined  // data field and run it...  WNDPROC original = (WNDPROC)GetWindowLong(hWnd,GWL_USERDATA);  return CallWindowProc(original, hWnd, msg,wParam,lParam); }