his.xmlhttp.onreadystatechange = ajaxCb(this.xmlhttp, req);
    if(req.method === "GET"){
      this.xmlhttp.open(req.method, req.url+p, true);
      this.xmlhttp.send();
    } else {
      this.xmlhttp.open(req.method, req.url, true);
      if(p instanceof String)
        this.xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
      this.xmlhttp.send(p);
    }
  },
  stop: function(){
    if(this.running) this.running = false;
    if(this.xmlhttp && this.xmlhttp.readyState < 4){