release notes are here but are fairly compact.https://sdkdocs.roku.com/display/sdkdoc ... -10/2/2017
updates to SDK documentation are coming.
If a track list is provided, and the language fields are set to the proper 3 letter code, and SubtitleConfig is not overriding the automatically selected track, then in 8.0 firmware the next video will select the track with the same language (could be a different track)..
The caption track list will show, for example :
Show French captions when Available
Currently showing English
Captioning Track <*French>
The *entry is the preferred caption language.
If that track is not available, it will still show up in the list ... but "Currently showing" will specify the track that is actually selected.
(Note I mentioned TED channel as an example before ... but it was not a good example ... there the channel defaults to the first track each time).
Main thing is to not use SubtitleConfig ... for backwards compatibility the firmware is forced to select that track and has to forego automatic track selection based on language.