function change( id, source) {
         var img;
         img = document.getElementById(id);
         img.src=source;
         return true;
}

function show() {
         img = document.getElementById('povidka');
	 img.className="disp";
}

function changeClass(Elem, myClass) {
	var elem;
	if(document.getElementById) {
		var elem = document.getElementById(Elem);
	} else if (document.all){
		var elem = document.all[Elem];
	}
	elem.className = myClass;
}