var ccount = 0;
    function checkCounter(msg){
            ccount++;
            if (ccount > 1) {
                   alert(msg);
                   return false;
             }
             return true;
     }



function popupWindow(url) {
  window.open(url,'popupWindow','toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,resizable=yes,copyhistory=no,width=100,height=100,screenX=150,screenY=150,top=150,left=150');
}

function oselect(option){
	
	var complete = 0;
	if(option==1)complete = 1;
	for(var j=0;j<document.cart_quantity.length;++j){
		if(document.cart_quantity.elements[j].type=='checkbox'){
			if(document.cart_quantity.elements[j].name == 'id[1]' && !complete) {
				document.cart_quantity.elements[j].checked = false;
				return;
			}
			else if(document.cart_quantity.elements[j].name != 'id[1]' && complete)   document.cart_quantity.elements[j].checked = false;
		
		}
	}
	
}

function blend_in(div) {
	document.getElementById('terzio').style.display = 'none';
	document.getElementById('tivola').style.display = 'none';
	document.getElementById('usm').style.display = 'none';
	document.getElementById('braingame').style.display = 'none';
	document.getElementById(div).style.display = 'block';
	return;
}