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 expires = "";
    document.cookie = name+"="+value+expires+"; path=/";
}

function showHideBlock(elementid)
{
    if (document.getElementById(elementid).style.display == 'none'){
        document.getElementById(elementid).style.display = '';
        createCookie(elementid, 'y', 30);
    } else {
        document.getElementById(elementid).style.display = 'none';
        createCookie(elementid, 'x', 30);
    }
}