Re: Failed English comprehension
It is not an assumption that they modified code. Their UI integrates the code which is GPL'd and therefore must also be GPL'd. They have not provided ANY of their own code.
I'm not assuming that all open source is GPL'd, they have used GPL'd code so that is the licence that is relevant to this discussion.
No one is asking for engine code, but they have not made any attempt to comply with the GPL at all. They have not provided their code for their software which incorporates GPL'd components they have simply tried to fob us off with the raw source for the components (which is not compliance).