Updated both:
Thank you Gabix. I managed to obtain words from other texts too. Could you please add them to the spell checker? You find them here: File on MEGA
I found a group working on Digital Pāli Tools. They are collecting so much material that I guess it will be possible to make a language pack for Pāli one day. If you are curious about the project, you can find here some guidelines:
Digital Pāli Tools - Google Docs
Thank you, Gabix! Very good!
Follow-up. Here is an updated extension for Pali spellcheck. It works (i. e. it suggests something on what I type in). Reminder: change the filename extension to .oxt before installing. Good luck!
Sorry, I have no idea how to install the Pali sample spellcheck extension but I trust you that it works. It is enough for me in order to continue to collect words. I have just to find out how it is best to do it.