Как определить, изменилось ли системное время?

Code:

type

TForm1 = class(TForm)

private

{ Private declarations }

procedure WMTIMECHANGE(var Message: TWMTIMECHANGE); message WM_TIMECHANGE;

public

{ Public declarations }

end;

var

Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.WMTIMECHANGE(var Message: TWMTIMECHANGE);

begin

Form1.Caption := 'Time Changed';

end;