Techwiki:Win32k/SMS

typedef struct _SMS
{                                  //Win2k
  struct _SMS  *psmsNext;          // 000
  struct _SMS  *psmsReceiveNext;   // 004
  DWORD         tSent;             // 008
  PTHREADINFO   ptiSender;         // 00c
  PTHREADINFO   ptiReceiver;       // 010
  SENDASYNCPROC lpResultCallBack;  // 014
  DWORD         dwData;            // 018
  PTHREADINFO   ptiCallBackSender; // 01c
  LONG          lRet;              // 020
  DWORD         flags;             // 024
  WPARAM        wParam;            // 028
  LPARAM        lParam;            // 02c
  UINT          message;           // 030
  PWND          spwnd;             // 034
  PVOID         pvCapture;         // 038
} SMS, PSMS;

// Flags 
#define SMF_REPLY           0x00000001
#define SMF_RECEIVERDIED    0x00000002
#define SMF_SENDERDIED      0x00000004
#define SMF_RECEIVERFREE    0x00000008
#define SMF_RECEIVEDMESSAGE 0x00000010
#define SMF_CB_REQUEST      0x00000100
#define SMF_CB_REPLY        0x00000200
#define SMF_CB_CLIENT       0x00000400
#define SMF_CB_SERVER       0x00000800
#define SMF_WOWRECEIVE      0x00001000
#define SMF_WOWSEND         0x00002000
#define SMF_RECEIVERBUSY    0x00004000

References

• userkdx