There is a Spanish language file in the source, but it has no translations in it .. the included es.po file is a collaboration between Google translate, my Spanish-English-Spanish dictionary, and various other sources.

Any involvement from a Spanish speaker to check and correct will be welcome. Kbabel is not necessary, it will display in a text editor just fine.

Tested with gnuchess-6.2.2, stockfish-7-linux, and komodo-7, in UCI mode.

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A themepack is available and will be included if pre-downloaded to the 'src' directory or downloaded during the build:

https://downloads.sourceforge.net/project/knights/knights-themepack/0.5.9/knights-themepack-0.5.9.tar.gz

If it's not in 'src', the build will continue with the default theme.