TWMMouseWheel = packed record
  Msg: Cardinal;
  Keys: SmallInt;
  WheelDelta: SmallInt;
  case Integer of
    0: (XPos: Smallint;
        YPos: Smallint;);
    1: (Pos: TSmallPoint;
        Result: Longint;);
end;

struct TWMMouseWheel {
  unsigned Msg;
  SmallInt Keys;
  SmallInt WheelDelta;
  Smallint XPos;
  Smallint YPos;
  TSmallPoint Pos;
  Longint Result;
};