User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.9.2.12) Gecko/20101026 Firefox/3.6.12 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.9.2.12) Gecko/20101027 Thunderbird/3.1.6 When filling out the subject field the content is spell checked in the current language. If the subject is in a different language it will be marked. But you can't change the language because the button is greyed. It can only be changed by clicking in the body first. Reproducible: Always Steps to Reproduce: 0. Have two dictionaries installed 1. Compose message 2. Fill in subject in currently not active language 3. Try to change language via menu button Actual Results: -> not working, button is greyed out Expected Results: Button to change language should be enabled Workaround is to click into the body, change language and then correct the subject with the help of the spelling checker