Fizzy (formerly Pixi) - pixel art and animation editor

[vancluever]

@flow

With MPL you’ve the first problem (could be forked to GPL) , but not the others I think.

Not necessarily, see MPL 2.0 FAQ — Mozilla, Q11:

How ‘viral’ is the MPL? If I use MPL-licensed code in my proprietary application, will I have to give all the source code away?

No. The license requires that Modifications (as defined in Section 1.10 of the license) must be licensed under the MPL and made available to anyone to whom you distribute the Source Code. However, new files containing no MPL-licensed code are not Modifications, and therefore do not need to be distributed under the terms of the MPL, even if you create a Larger Work (as defined in Section 1.7) by using, compiling, or distributing the non-MPL files together with MPL-licensed files. This allows, for example, programs using MPL-licensed code to be statically linked to and distributed as part of a larger proprietary piece of software, which would not generally be possible under the terms of stronger copyleft licenses.

And Q12:

How does the scope of the MPL’s copyleft compare with the LGPL and GPL’s copyleft?

Broadly speaking, the scope of the MPL, LGPL, and GPL can be summarized this way:

MPL: The copyleft applies to any files containing MPLed code.
LGPL: The copyleft applies to any library based on LGPLed code.
GPL: The copyleft applies to all software based on GPLed code. 

However, we would recommend reading the licenses to better understand their scope, and in particular, to understand how the LGPL and GPL define “based on.”

So, from my reading of this, my impression (and also as someone who uses the MPL himself) is that while a larger project could be GPL, any imports of source code and modifications to said MPL code would still need to be made available under the MPL. Of course, there’s lots of ways to work around this, but reasonably most of those entail the guarantee that if your work needs to be modified for that to happen (e.g., maybe more portability to enable better integration), that those modifications would need to be paid forward under the MPL.