function fp_ie4() {
	var nav = navigator.appVersion.indexOf("MSIE");
	return (nav>0) && (parseInt(navigator.appVersion.substring(nav+5, nav+6)) >= 4);
}

function fp_ns6() {
	return ((navigator.appName == "Netscape") &&
				(parseInt(navigator.appVersion.substring(0, 1)) >= 5))
}

function UkazObr(idecko, velka)
{	
  var hlavni = "hlavni_"+velka 
	var el = document.getElementById(hlavni);
	if (el) {
		if(fp_ie4()) {
			el.style.visiblity = "hidden";
			el.src = idecko;
		}else {
			el.src = idecko;
		 }
	}
}