In BS.Player 2.57.1047β (201011161215) new features were introduced, i.e. ...
(1) ... an option to change background color for full screen mode.
However the text "Video background color" is not in the language file!
(2) ... a new OSD mode.
However, it appears that the users' options under OSD preferences "Use new OSD mode" and "Transparent" do not go together (as the new OSD mode always has a solid background). Consequently selection of one should automatically deselect the other.
Further IMHO this second new feature makes it even more necessary to change the text "OSD sample" into "OSD font sample". (I've done so in my translation.)