Fcitx have two prefixes of directory, one is named "PREFIX", which is configured during building, the other is "USERPREFIX", which is based on XDG environment variable. Normally, PREFIX is /usr/share/fcitx, and USERPREFIX is ~/.config/fcitx

In order to let Fcitx Configuration Tool find configuration files automatically, and to let Fcitx load addon correctly, addon need to put its configuration files under correct path with correct name.

Each addon has a configuration file, and it should be installed under PREFIX/addon/. This configuration file defines its name, category, library name, type, and priority. Filename need to be addon-name.conf.

If addon can be configured with various options, it need a configuration description file, which should be installed under PREFIX/configdesc/, with name [addon-name].desc. The corresponding configuration file should be placed under USERPREFIX/conf/, with the name [addon-name].config.

There are two case If addon has some data file to load/save. If it only has one file, it can place the data file under PREFIX/data. If addon have more than one data file, it would be better to create a separate directory to place them.