Ajax.Request.prototype.abort = function() {
        // prevent and state change callbacks from being issued
        this.transport.onreadystatechange = Prototype.emptyFunction;
        // abort the XHR
        this.transport.abort();
        // update the request counter
        Ajax.activeRequestCount--;
        if (Ajax.activeRequestCount < 0) {
                Ajax.activeRequestCount = 0;
        }
};