The Retrostep distribution may contain works released under the GPL for various reasons (as mere aggregation).  These files may not be linked with retro files released under the Artistic License because the GPL does not allow it. The GPL explicitly does not allow dynamic linking with non-GPL modules. That means that if you use a module released under the GPL with retro, you are probably violating the license of that Module.

The GPL is somewhat impractical for a program like litestep or retro where most things are implemented as modules, because it limits your freedom regarding what modules you may legally use.  That is probably the reason why most litestep users wrongfully just ignore the GPL. It is also the the reason why retro is not released under the GPL. Otherwise, the GPL grants everyone the permission to use and modify programs released under the GPL just like the retro license.  As a developer, the GPL may limit your freedom to distribute code released under the GPL, but it neither attempts to, nor can it cannot restrict what you code because most people my freely exercise their right of free speech.

For information about the Retrostep and retro, please see http://rs.obada.com/whatis.html

For information on the GPL please consult http://www.gnu.org/gnu/manifesto.html, http://www.gnu.org/licenses/gpl.html and http://www.gnu.org/licenses/gpl-faq.html

To understand other reasons why one may not want to release their work under the GPL, please look up these documents:

• Restrictively Unrestrictive: The GPL License in Software Development [http://www.daemonnews.org]
• Real benefits of truly free software [http://static.userland.com]
• GPL, Artistic, Retrostep And Me [http://rs.obada.com]
• The GPL Considered Harmful [http://www.morons.org]
• Martin Cracauer's GPL Page [http://www.cons.org]
• Why Cooperation with RMS is impossible. [audio]

For a deeper look at what's wrong with the GPL, follow the link below and read up about the GPL, it's creator and try to make you own oppinion:

Richard Stallman vs. Brett Glass [google search]