Actually as long as Microsoft doesn't modify the program, isn't it the case that Mozilla can't revoke their ability to distribute it? It's released under the GPL isn't it? I guess that opens the question of whether a change in the configuration is a derivative work or just a compatibility change. I'm not a lawyer, though, it's above my pay grade.<p>Actually it's not. If Canonical can do it, I guess Microsoft ought to be able to as well.