Thread:Talk:Files and licenses concept/And the whole content?

I think I overlook something. I define somewhere in my mediawiki a general ToS, this include a sentence like "All the content of this wiki have the CC-BY-SA license (or whatever), apart from pictures. Pictures have an own license that the uploader of the file want to use." The uploader of a screenshot now choose e.g. GPL. How can I share the whole wikisite (text and pictures) now, without any licence problems?