function new_win(a_url, a_name, a_prop, a_sirka, a_vyska)
{
	o_sirka = screen.width;
	o_vyska = screen.height;

  if ((a_sirka == "") && (a_vyska == ""))
  {
    a_sirka = 400;
    a_vyska = 300;
  }

	a_leva = (o_sirka - a_sirka) / 2;
	a_horni = (o_vyska - a_vyska) / 2;

	o_prop = ',width=' + a_sirka + ',height=' + a_vyska + ',left=' + a_leva + ',top=' + a_horni;

  if (a_url != "") 
	{
		var okno = window.open (a_url, a_name, a_prop+o_prop);
		okno.creator = self;
	}
}