Intercepting redirects in XMLHttpRequest

Hi all,

I am trying to write an extension that makes use of XMLHttpRequest - the 
reason I want to use this is because I need to send extra headers to the 
server when I make the requests. Occasionally, the reply will be a 302 
redirect which I want to intercept and make the current window navigate to 
that url.  I can't see any way of doing this.

I am sure that there is something I am missing. If anyone knows of a way to 
do this - ideally so that I can get the header of the redirect (there will 
be other information in the header that woiuld be useful for me) then I 
would be really grateful.

Cheers,

Milamber³