Qt/XEmacs vs. the GPL (was: Re: kde-xemacs or gnome-xemacs?)

There is a lot of misunderstandings in this thread. I have spend a lot of time on these issues, and I believe I can state both the FSF position and the opposition. Please read. 1. FSF position: GPL'ed code can be distributed linked with code under any license that has no restriction that are not also in the GPL. This means you can link and distribute with PD code, X11 code, and LGPL code, as all these have fewer restrictions that the GPL. The BSD license and the QPL both have additional restrictions, so they are not GPL-compatible, even though they are "free software". Traditionally, the FSF has ignored violations when people have linked with non-GPL compliant free software. I have no idea if this will begin to include QPL now that it has become free software. Opposition: Recently a lot of people have started claiming that _only_ the GPL is compatible with the GPL. This seem to be a meme based on a misunderstating, rather than on someone who know the law. I haven't seen it backed (nor refuted) by those people who know the law. It is always people repeating what they have read other people say on the net. 2. FSF position: There is no distinction between static and dynamic linking. Not even if you don't distribute the dynamic library. Opposition: There are. If the user does the link, the GPL does not apply. 3. FSF position: The FSF has ignored the issue of include files, it has been irrelevant because of their position on dynamic libraries. 4. FSF position: Motif is a "standard system component", and can therefore be linked with GPL software. Opposition: That is by no mean clear. 5. FSF position: Qt is _not_ a "standard system component". However, this position may have changed since Qt is now part of most Linux distributions. Opposition: That is by no mean clear. 6. FSF position: Distributing GPL _source_ that depend on non-system GPL-incompatible libraries are a violation. Opposition: No way! So the situation is: Given how heated the KDE/Qt vs GPL debate was, it is almost certain that RMS will be forces to comment on a Qt/KDE enabled XEmacs. The most likely outcome is that a source distribution will be OK, as long as you still can build XEmacs without Qt, while a binary distribution will be seen as a violation of his copyright. It is not certain that a court will agree with RMS. My *opinion* is that RMS, although he disagree with the project, never has challanged the XEmacs developers right to do what they do. It would be stupid to change that now. So ask first.