function Is24HourTimeFormat: Boolean;
var
  DefaultLCID: Windows.LCID;  // thread's default locale
begin
  DefaultLCID := Windows.GetThreadLocale;
  Result := 0 <> SysUtils.StrToIntDef(
    SysUtils.GetLocaleStr(DefaultLCID, Windows.LOCALE_ITIME, '0'),
    0
  );
end;
//delphi/2172