You add it but it doesn't work. As expected.

Helaas nog maar één ster. Was prima maar sinds de laatste updates van Firefox worden de taalpaketten wel geïnstalleerd (ik gebruikte NL, GB, DE en Fr) maar kan ik ze niet meer oproepen...

good

I see many people being confused that this addon does nothing when they want to spellcheck something. This addon is made for your browser language, the language which the browser uses as default for things like Settings(Instellingen) and it is not a dictionary for spellcheck.

A completely useless language pack, because after installing it doesn't do anything