Any help would be appreciated, since I'm really stuck with this....

Hi all,

In case anyone is struggling with the same problem. I found an answer: Just put this in your custom javascript.

Snippet

(function(XHR) {
    "use strict";

    if (typeof(XHR.prototype.wasPatched) != "undefined") return;
    XHR.prototype.wasPatched = true;

    var open = XHR.prototype.open;
    var send = XHR.prototype.send;

    XHR.prototype.open = function(method, url, async, user, pass) {
        this._method = method;
        this._url = url;
        this._async = async;
        this._user = user;
        this._pass = pass;
        open.call(this, method, url, async, user, pass);
    };

    XHR.prototype.send = function(data) {

        var self = this;
        var oldOnReadyStateChange;
        var url = this._url;
        this._data = data;

        function onReadyStateChange() {
            if(self.readyState == 4 /* complete */) {
                /* This is where you can put code that you want to execute post-complete*/
                /* URL is kept in this._url */
                if (this._url.indexOf("Formatting.xslt") != -1) 
                {
                    // Because setTimeout is fired in another thread the main thread will be finished when this function is  called. So 1 ms is enough
                    setTimeout(function () { debugger; yourFunction(); }, 1);
                }
            }

            if(oldOnReadyStateChange) {
                oldOnReadyStateChange();
            }
        }

        /* Set xhr.noIntercept to true to disable the interceptor for a particular call */
        if(!this.noIntercept) {            
            if(this.addEventListener) {
                this.addEventListener("readystatechange", onReadyStateChange, false);
            } else {
                oldOnReadyStateChange = this.onreadystatechange; 
                this.onreadystatechange = onReadyStateChange;
            }
        }

        send.call(this, data);
    }
})(XMLHttpRequest);