How to get XSLTProcessor.transformToDocument output in a tab/document?

Hi,

How do I display a XSL Transformed XMLDocument(fragment) after
reading it in with XMLHttpRequest.open("GET", aURL) ???

Something like this works when I first load the XML uri into a tab:

var ownerDocument = document.implementation.createDocument("", "", null);
var newFragment = processor.transformToFragment(doc, ownerDocument);
var _documentElement = doc.documentElement;

while (_documentElement.hasChildNodes())
   _documentElement.removeChild(_documentElement.firstChild);
_documentElement.appendChild(newFragment);

But I don't want to load it into a tab.
I just want to load it, transform it and put the output into a tab.
I use this:

var newDocument = processor.transformToDocument(XMLHttpRequest.responseXML);

instead of method transformToFragment (I hope that's the right thing use)
without any warnings and errors, so it seems to be fine but...there's no
output. Or when I change it a little, the complete window is overwritten
replaced with the backgkround of my XSL stylesheet and a text for empty
sidebar is displayed, so I must be doing something very wrong.

Again, everything works when I call my function *after* entering the URL 
into
the locationbar, but that's not what I want!

Uhg, I hope I made myself clear.
I whish my English was a little better--maybe next year ;)

TIA
Michael