activities.defaults should be a /etc file

[quidam]

The activities.defaults config file, like any other Sugar config file, should be located in /etc instead of /usr/share/sugar/data/

Maybe a /etc/sugar directory would be useful.

Another approach would be to have the default files at /var/lib/sugar/ (/usr files are not supposed to be modifiable at runtime), and if a /etc/sugar/ file with the same name exists, use that one instead.