problems with relative paths when loading a doc from memory

[Rainer Kugeland]

hi,

i want to edit a document whose sourcecode is already edited in memory.
that's why i try to load the doc like this:
GetCurrentEditorElement().webNavigation
.loadURI("data:application/vnd.mozilla.xul+xml;charset=utf-8," + 
escape(source),
nsIWebNavigation.LOAD_FLAGS_BYPASS_CACHE, null, null, null);

This works fine. The only problem is that all images are broken because 
I can'T define a base url so that all relatives paths work.

Any ideas?

Thanks

RK