The following example demonstrates trapping the WM_TIMECHANGE message. Note: Applications that change the system time should broadcast a WM_TIMECHANGE message to all top level windows.

type
  TForm  = class(TForm)
  private
    { Private declarations }
    procedure WMTIMECHANGE(var Message: TWMTIMECHANGE);
       message WM_TIMECHANGE;
  public
    { Public declarations }
  end;
var
  Form : TForm ;
implementation
{$R *.DFM}
procedure TForm .WMTIMECHANGE(var Message: TWMTIMECHANGE);
begin
  Form .Caption := 'Time Changed';
end;