What I'm saying is that the people who wrote KHTML have copyright over Webkit. They released their code under the LGPL, and its Apple's obligation to honor this license until they remove all the original code or get contributers to sign a copyright assignment form. That's how open source projects work: either all the code is owned by some central entity, or the code is owned by the various contributers. When the code is owned by the contributers, your patch is considered a derivative work (for the purpose of copyright) of the other copyright holders' work, so you have to follow the license. On the flip side, if every patch has documentation saying that the central authority (the FSF, the Apache Foundation, etc.) has copyright, then that central authority can relicense however they want. For example, Emacs is now GPLv3, even though most of the code was written well before the GPLv3 existed.
In the case of Webkit, Apple does not require copyright assignment. The code was not originally theirs - their version of Webkit is a fork of KHTML, and so the copyright from KHTML is in force. They have to follow the LGPL, because otherwise they have no legal right to use the code in their products.
That's all I'm saying: the question was "who has a legal claim over Webkit", and my answer was "everyone who's contributed".
The LGPL allows Apple to keep the rest of their stack that links against Webkit proprietary. However, they have to release their changes to Webkit.
Here is the exact wording from the LGPL v2:
These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Library, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Library, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it.
The LGPL allows Apple to keep the rest of their stack that links against Webkit proprietary. However, they have to release their changes to Webkit.
Quite right, but for this point of pedantry: Apple's fork of KHTML is known as WebCore. That part is LGPL. WebKit (the encompassing project) is BSD and always has been. Safari (the browser) is proprietary.
As far as I can tell, Apple's changes to WebCore are in the public repo. e.g.
This is not specific to the GPL. You can't change the license unless the copyright owners agree. That applies for any software license or really anything copyrighted.
Some things are easy because the license specifically permits it: you can GPL a BSD-licensed project, for example. In that case, the agreement from the copyright holders comes in the form of the terms of the license.
But you cannot relicense a BSD-licensed project as GPL because only the original rights-holder can do that. You can apply the GPL on top of the BSD license because the GPL is more specific than the BSD license (ie GPL is a restricted subset of the BSD license, kinda). You must still make the original BSD-licensed code available under the BSD license.
In the case of Webkit, Apple does not require copyright assignment. The code was not originally theirs - their version of Webkit is a fork of KHTML, and so the copyright from KHTML is in force. They have to follow the LGPL, because otherwise they have no legal right to use the code in their products.
That's all I'm saying: the question was "who has a legal claim over Webkit", and my answer was "everyone who's contributed".
The LGPL allows Apple to keep the rest of their stack that links against Webkit proprietary. However, they have to release their changes to Webkit.
Here is the exact wording from the LGPL v2:
These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Library, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Library, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it.