Rainer, there are a few reasons why this question has a complex answer:
1) Mozilla has undergone a relicensing process, and so you need to make sure of what licenses the files you are wanting to use from Mozilla are under. Not all files in the Mozilla tree are neccessarily available under the same license
That's not actually true - they are all (or should all be; tell me if you find an exception) available under the MPL/NPL (which are the same for any normal purposes.)
None of this is meant to negate what anyone else has said about not getting legal advice in a newsgroup ... but maybe you didn't know where on the web to look for the info, hopefully that helps
The n.p.m.license group is there to help people who want to develop using mozilla.org-hosted code; but it's for questions like "I've read section X.X of the MPL carefully, and can't work out whether I have to do foo when bar and baz are true, but quux is not.", rather than "I'm writing a Mozilla-based app. What do I have to do under the license?"
Gerv
