When in writing I need to switch from ENG to RUS and back I use clever little phonetic plug-in from FireFox stock called AnyKey. It is tied to F2 button made to act as toggle.
It works for all my email, until recently @gmail it stopped working completely and now I can only write and reply email in ENG.
Since I use it for communicating with my parents (they write in Russian), I’d very much prefer to restore this setting – except I don’t know where to go and what button to click.
I looked in all the gmail Settings and didn’t find anything remotely close.