var ibth=0;
function ibt(obj,st){
	var str="";
	if(ibth==2) return;
	switch (st){
		case 3:
			str="0px -36px";
			break;
		case 2:
			str="0px -42px";
			break;
		case 1:
			str="0px -21px";
			break;
		default:
			str="0px 0px";
			break;
	}
	ibth=st;
	obj.style.backgroundPosition=str;
}