Spell check of Thunderbird

    Even though my default language is Estonian in an Estonian Thunderbird 10.0.0, a dialog box of the spell check shows that the default language is Finnish and I can't change it into other languages like Estonian, Russian and British English. The same problem was in the previous version of Estonian and British English mailer, what were published in December. If I write a message in Finnish, then the spell check works correctly. Forbidding or in other words deactivating, but not removing an add-on of Finnish spell-checker, what can be downloaded from https://addons.mozilla.org/en-us/thun..., British English, Estonian and Russian spell-checkers act properly.
    In Thunderbird 10.0.1 works the spell check with updated spell-checkers nicely.