XMLHttpRequest in the non-Main thread

Hi,

Is it possible to get working the XMLHttpRequest in the non-main
thread of the XulRunner/XPCOM extension ?

The code that works in the MainThread, seems to block on the
'do_CreateInstance(NS_XMLHTTPREQUEST_CONTRACTID, ...)' when placed
into the child thread.
At this moment the following log appears:
424[46aea10]: ###!!! ASSERTION: trying to suspect from non-main
thread: 'NS_IsMainThread()', file c:/SCM-temp/mozilla/xpcom/base/
nsCycleCollector.cpp, line 2121


On the other (not proper for this question) Mosilla mailing list I've
got the answer 'NO', but without any explanation .

Kind wishes,
Viktor Tarasov.