var exp=20

var backgs=new Array
backgs[0]="mas_main_bg_green.jpg"
backgs[1]="mas_main_bg_grey.jpg"
backgs[2]="mas_main_bg_dark.jpg"

function bgChange(){
if (backgs.length>2)
backgs.push([backgs.shift()])
for (i = 0; i < backgs.length; i++)
if (document.body.background!==backgs[i]||document.body.style.backgroundImage.toLowerCase()!=='url('+backgs[i].toLowerCase()+')'){
document.body.style.backgroundImage='url('+backgs[i]+')'
break
}
}

function get_cookie(Name) { 
var search = Name + "="
var returnvalue = "";
if (document.cookie.length > 0) {
offset = document.cookie.indexOf(search)
if (offset != -1) { 
offset += search.length
end = document.cookie.indexOf(";", offset);
if (end == -1) end = document.cookie.length;
returnvalue=unescape(document.cookie.substring(offset, end))
}
}
return returnvalue;
}

function onloadfunction(){
var acookiename="abgchange"
var acookievalue=get_cookie(acookiename)
if (acookievalue!=""){
backgs=eval(acookievalue)
document.body.style.backgroundImage='url('+backgs[0]+')'
}
}

function saveBgrnd(){
var abackgs='["'
for (i = 0; i < backgs.length; i++)
abackgs+=backgs[i]+'","'
abackgs=abackgs.substr(0,abackgs.length-2)+']'
var acookiename="abgchange"
var date = new Date();
date.setTime(date.getTime()+(exp*24*60*60*1000));
var expires = exp? "; expires="+date.toGMTString() : ""
var acookievalue=abackgs+expires+"; path=/" 
document.cookie=acookiename+"="+acookievalue
}

if ( typeof window.addEventListener != "undefined" )
    window.addEventListener( "load", onloadfunction, false );
else if ( typeof window.attachEvent != "undefined" ) {
    window.attachEvent( "onload", onloadfunction );
}
else {
    if ( window.onload != null ) {
        var oldOnload = window.onload;
        window.onload = function ( e ) {
            oldOnload( e );
            onloadfunction();
        };
    }
    else
        window.onload = onloadfunction;
}

window.onunload=saveBgrnd