app-misc/xmind breaks FHS by installing its file in /opt
FHS allows installing software to /opt, see [1]. Given that app-misc/xmind installs precompiled binaries it's perfectly sane to put them in /opt. [1]: https://refspecs.linuxfoundation.org/FHS_3.0/fhs-3.0.html#optAddonApplicationSoftwarePackages