window.open and problems with content-type

[s0s]

Hi

I'm trying to generate site source dynamically at the server side (PHP) and show it in new window in client browser.

In javascript I have new window creation:
var winref = window.open('', 'Form', 'left=20, top=20);
winref.document.writeln(response);
winref.document.close(response);

and the "response" comes from:
var response = HttpRequest.responseText;

On the server side I have easy code (server.php):
<?php
header ("Content-type: application/vnd.mozilla.xul+xml; charset=iso-8859-15");

... rest of site (in XUL)

?>

Server side looks fine:

http://localhost/server.php

works great and the content-type is correctly XUL

But if I use javascript and window.open I have still content-type "text/xml" and it's not so fun

How can I change this?
I've found this way

httpRequest.setRequestHeader("Content-Type", "application/vnd.mozilla.xul+xml");

but it still don't solve my problem

--
sebo