Themes for the Xojo IDE (and for the now-confusingly-named XojoThemes) are now on GitHub. Just the themes. The now-confusingly-named XojoThemes is not open-sourced yet. But the themes are compatible with it. And the IDE. Is that clear?
Contributions welcome!
https://github.com/gavinlibertyapp/xojothemes (the themes for Xojo)
http://www.libertyapp.com/xojothemes/ (the confusingly-named XojoThemes)