While the initial controversy about the Thesis-not-being-under-GPL issue was focused on themes and derivative works, an unclear area that probably needs to be resolved in court, it seems there is a far sounder reason why Thesis has to be released under the GPL: it blatantly copies WordPress code.
It all started with this tweet by Andy Peatling (@apeatling):
Not a clear GPL violation, because it’s extending WordPress classes, which, in effect, copies WordPress functionality into Thesis.
Andrew Nacin (@nacin) started going through the code of Thesis and started to make some encouraging/discouraging tweets:
And then, an initially uncorroborated claim:
At this point, it seems clear: Thesis isn’t merely building on top of WordPress, it literally incorporates WordPress code through copy-paste.
That makes Chris Pearson liable to fulfill his obligations under the GPL and distribute GPL derivatives under the GPL.
Andrew Nacin eventually found this in Thesis:
* This function is mostly copy pasta from WP (wp-includes/media.php), * but with minor alteration to play more nicely with our styling.
GPL test case? YES.
Chris Pearson indicated during his interview that he is fundamentally opposed to the GPL and will absolutely refuse to license Thesis under the GPL. By the end of the dialogue, he was practically saying “sue me”.
Matt Mullenweg responded:
Matt: Are you saying you want to be a test case for the GPL? You want us to sue you? I mean, that would break my heart. I’d rather you be part of the family.
While the themes = derivatives basis might have been shaky for a legal trial, I think the fact that there’s copied code clearly indicates one outcome in the end, in favour of the GPL.
Temporarily back to the case for themes = derivatives
WordPress isn’t the first community to issue the directive that extensions (themes, plugins) are derivatives. Joomla! did so a few years ago (I recall because I used Joomla! before finding WordPress) and Drupal makes it extremely clear.
If this matter can’t be determined by the GPL’s applicability to themes/plugins, maybe WordPress should just re-license, starting with a future version, with GPLv3 and add a specific requirement that themes/plugins are licensed under GPL.