procedure TForm1.Button2Click(Sender: TObject);
var
rv : dword;
tt : tdatetime;
begin
SetLocaleInfoa(LOCALE_SYSTEM_DEFAULT,LOCALE_SSHORTDATE,PChar('yyyy.MM.dd'));
SendMessageTimeout(HWND_BROADCAST, WM_SETTINGCHANGE, 0, LParam (PChar('sShortDate')), SMTO_ABORTIFHUNG, 5000, rv);
end;