Now I get it... Basicly, the lawyers are trying to come up with a licence for the art that: A.says something like "you can use this art as part of a program based on mozilla but not in a program thats totally unrelated to mozilla" but also B.is compatible with the MPL, the GPL and the LGPL.
IANAL but I wouldnt think that A is very hard (I see what I guess is similar kinds of language in for example the redistribution licence for rultime libraries of compliers that say "you can distribute these runtime dlls for use with a program built with this compiler but not on their own"). I am guessing that satisfying point B is hard without changing all 3 licences involved.
