function createCookie(name,value,days) {
	if (days) {
		var date = new Date();
		date.setTime(date.getTime()+(days*24*60*60*1000));
		var expires = "; expires="+date.toGMTString();
	}
	else var expires = "";
	document.cookie = name+"="+value+expires+"; path=/";
}

function readCookie(name) {
	var nameEQ = name + "=";
	var ca = document.cookie.split(';');
	for(var i=0;i < ca.length;i++) {
		var c = ca[i];
		while (c.charAt(0)==' ') c = c.substring(1,c.length);
		if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
	}
	return null;
}

function eraseCookie(name) {
	createCookie(name,"",-1);
}
	
function cOn(elem){
		
	$(elem).style.visibility="visible";
	$(elem).style.display="inline";
		
	var prevOn = readCookie('isOn');
	eraseCookie('isOn');
	if (prevOn) {
		cOut(prevOn);
	}

	createCookie('isOn', $(elem).id, 1);
}

function cOut(elem){
	if ($(elem)) {
		$(elem).style.visibility="hidden";
		$(elem).style.display="none";
	}
}