[Greasemonkey] GPL compatibility

[Mark Pilgrim]

On 6/3/05, Aaron Boodman <zboogs at gmail.com> wrote:
> Ok, I'm sorry but I still have two questions. (the same two)
> 
> * what is it specifically about GPL that makes you want to ensure that
> people can use it

I personally want to create standalone extensions and license them
under the GPL, and I can not currently do this.  The GPL is my default
license of choice, because it guarantees that derivative works remain
free.  (Case in point: the Butler derivative included with Trixie.) 
This in turn helps increase the ratio of useful free software to
useful non-free software, which I view as a good thing.

> * what is it specifically which makes AFL and MPL non-compatible with GPL.

So sayeth the Free Software Foundation's laywers (probably Eben Moglen):
"""
The AFL is incompatible with the GPL for two reasons. One is that its
rules about trademark use appear to go beyond what trademark law
itself actually requires in some countries, prohibiting what would
legally be fair use of the trademark.

Another incompatibility comes from its "Mutual termination for Patent
Action" clause. Putting aside the difficult question of whether this
sort of clause is a good idea or a bad one, it is incompatible with
the GPL.
"""
(source: http://www.gnu.org/philosophy/license-list.html)

I don't know what the story is on the MPL, but the Mozilla development
community went through some period of discussing licenses at length,
and settled on a combined license that allowed Mozilla code to be used
under the GPL in derivative works.  I don't recommend combined
licenses in general, since they create even more confusion than
individual licenses create already.  Since we're so early in the
lifecycle, it would be easiest to just relicence GM entirely under the
GPL (or some other GPL-compatible license).

-- 
Cheers,
-Mark