The quick and dirty way. The problem: there is lots of text in IntellijIdea in custom languages, so a spell-checker would be nice to get at least those early on.

But no worries, turned out there is a way to add new directories, too.

Then the task is to find that ever important .dic file for the dictionary and found hints from :

Our unix machines ispell, aspell does have Finnish, which was the one I wanted. The first command below lists the available dictionaries and the rest grab the dictionary part in some way.

aspell dump dicts 
aspell -d en dump master > en.dic
aspell -d fi dump master > fi.dic
aspell -d sv dump master > sv.dic

Aspell also have new dictionaries: ftp://ftp.gnu.org/gnu/aspell/dict/0index.html , which one can install (unzip, configure, make, make install path) and then grab those also to windows in above manner

Settings demo

This might require restart, but I believe otherwise spelling check should now be on when doing texts in IntellijIdea.