//overflow.js
function init() {
    if(document.getElementById && document.createTextNode) {
        var overflow = document.getElementById('overflow');
        overflow.scrollTop = getLastUrlParam();
        var as = overflow.getElementsByTagName('a');
        for(var i=0, length=as.length;i<length;i++) {
            as[i].onclick= function() {
                this.href = addUrlParam(this.href, '_s', overflow.scrollTop);
            }
        }
    }
}

addUrlParam = function(href, key, value) {
    return href+(href.split('?').length==1?'?':'&') + key + '=' + value;
}

getLastUrlParam = function() {
    var parts = location.href.split('=');
    return parts[parts.length-1];
}

window.onload=init;