function lightup(imgName)
 {
   if (document.images)
    {
      imgOn=eval(imgName + "on.src");
      document[imgName].src= imgOn;
    }
 }

function turnoff(imgName)
 {
   if (document.images)
    {
      imgOff=eval(imgName + "off.src");
      document[imgName].src= imgOff;
    }
 }

function kalkulacka(co)
{
	if (document.kalkulacka)
		if (!document.kalkulacka.closed)
			document.kalkulacka.close();
	document.kalkulacka = window.open(co,"kalkulacka","width=200,height=100,resizable=no,scrollbars=no");
}