Matt Mullenweg, the creator of WordPress, is engaged in a battle of words with the maker of one of its premium themes, Chris Pearson, who runs DIYthemes and offers the Thesis theme on a paid-for basis. I listened to their discussion on Mixergy; it is ill-tempered particularly on Pearson’s side.
The issue boils down to this. WordPress is licensed under the GPL, which provides that if you derive a new work from an existing GPL-licensed work, the GPL applies to your new work as well.
Pearson argues, I think, that his work is not so tightly linked to WordPress that the GPL applies. “Thesis does not inherit anything from WordPress” he says.
Mullenweg says that the way themes interact with WordPress is such that all themes much be GPL. “If you build something on top of it, it should be GPL” he says.
Pearson is refusing to license his theme under the GPL. What is to be done – would Mullenweg go to court to protect the GPL?
“You want us to sue you? That would break my heart.” he says. Then later, “I really hope it doesn’t come to that.” Then, “If people decide the GPL doesn’t apply, it’s a serious step for open source.”
Disclosure: this site runs on WordPress and I regard Mullenweg as one of the heroes of open source. Like the Apache web server (also in action here), WordPress is among the greatest achievements of the open source community.
I have no legal expertise; though I know a little about how WordPress works. Themes link very tightly with WordPress and in most cases are built by modifying an existing GPL theme; but I guess if you could show that Pearson’s work does not do this but merely runs on WordPress, as opposed to modifying it, he may have a case. That’s the argument Michael Wasylik makes here. On the other hand, did Pearson really create his theme without including any tiny bit of GPL code?
Another factor: if you choose to build an extension to a platform like WordPress, it is arguably unwise to do something counter to the strong wishes of its founder. There are ethical as well as legal aspects to this.
It is an important discussion for the open source community.