The viewer’s source is released under the GPL2, however, some components use other licenses.
Most parts of the viewer can be redistributed by people making their own viewers. One exception is Kakadu, the JPEG 2000 library. This is the component that decodes textures. Its license prevents distribution by anybody but Linden Lab. Fortunately, there’s an alternative, called OpenJPEG.
The reason SL doesn’t use it by default is that it’s still not as good as Kakadu. Initially, OpenJPEG was very, very slow. It worked as a proof of concept, but it was unusable in practice. Every texture decoding made the viewer freeze, and it could take half an hour until things loaded. Fortunately, some of the other people working on the viewer contributed patches, and now performance is more than acceptable.
A few problems remain, however: OpenJPEG still has bugs Kakadu doesn’t, for example the problem with the world map is an OpenJPEG bug. It also crashes when uploading small images and has other uploading problems.
These bugs may manifest themselves in my viewer if you didn’t have the right original version of SL installed when you installed mine. This is because since Kakadu is not redistributable, my installer takes it from an existing install, if it can be found. If not, the viewer falls back to OpenJPEG. You’ll get a message about this during installation if the installer can’t find the file. To fix that is easy: Install the original SL version my viewer is based on (126.96.36.199 for example), then reinstall my viewer. FirstLook, beta, etc versions most likely won’t work, as the installer looks for a specific version of the file.
Currently I can’t fix those problems. Besides not being a problem with the viewer itself, I don’t know enough about image compression to figure out the problem. I could try to learn, but I think my time is better spent on my current work, especially since there are people who know about OpenJPEG a lot more than I do. If you want to help, vote for those bugs. Login with your SL username and password into Jira, then click “vote for it” on the left sidebar. This will help bring it to the LL’s attention.