Redmine

Redmine instances have a default locale setting (admin > settings > display) but this setting is only used when these two conditions are met:

1. User is not logged in
2. User's browser doesn't publish an HTTP_ACCEPT_LANGUAGE value

So, the current locale scheme is the following:

1. User specified locale
2. User browser default locale
3. Redmine default locale

AMHO, redmine should switch the last two for:

1. User specified locale
2. Redmine default locale
3. User browser default locale

Why? Because a not-logged in user should see what the redmine owner want him to see first, then let the user choose what locale he wants to see (once registerd and logged in). This way, it's easier to see what's the main language on that redmine instance and avoid a wide part of the risk to have question and bugs fills with user mother-tongue messages.