Analysis of information sources in references of the Wikipedia article "GeoGebra" in English language version.
Following a closer inspection at the licensing terms GeoGebra authors use, I noticed that GeoGebra isn't free anymore, starting from version 4.2.
[...] at least the language files are required to build the program.
However, if the language file carries a GPL-incompatible license (such as CC-BY-SA), the resulting product cannot be distributed in a legal way.
Besides the fact that it seems invalid, it also ships Jlatexmath (which I co maintain) which is published under the GPL v2.