function get_cookie(cookie_name) {
  var results = document.cookie.match ( '(^|;) ?' + cookie_name + '=([^;]*)(;|$)' );

  if ( results )
    return ( unescape ( results[2] ) );
  else
    return null;
}

var changeLocked = "no";
var onBG = 1;
var storedCookie = get_cookie("bgimage");

function setBG() {
	if(storedCookie != "") {
		switch(storedCookie) {
			case "1":
				changeBG(1);
				break;
			case "2":
				changeBG(2);
				break;
			case "3":
				changeBG(3);
				break;
			case "4":
				changeBG(4);
				break;
		}
	}
}

function changeBG(num) {
	if(changeLocked == "no") {
		changeLocked = "yes";
		$('mainContainer').className = "mainContainer" + num;
		$('bgicon'+onBG).src = "images/bg_icons_"+onBG+".jpg";
		$('bgicon'+num).src = "images/bg_icons_over"+num+".jpg";
		setTimeout(function() {
			onBG = num;
			document.cookie = "bgimage="+onBG;
			changeLocked = "no";
	 	}, 100);
	}
}