1  
 2  #include "WinHookEventIDs.h"
 3  #include <wtypes.h>
 4  #include <mutex>
 5  
 6  UINT WM_PRIV_SETTINGS_CHANGED = 0;
 7  
 8  std::once_flag init_flag;
 9  
10  void InitializeWinhookEventIds()
11  {
12      std::call_once(init_flag, [&] {
13          WM_PRIV_SETTINGS_CHANGED = RegisterWindowMessage(L"{11978F7B-221A-4E65-B9A9-693F7D6E4B25}");
14      });
15  }