Subtitle semi-transparent option?

[Blackstar]

Is there a way to have semi-transparent background (50% opaque or bit of see-thru) instead of pure solid black 'transparent' background? Sometimes there are certain area at bottom of screen like that show new tickers but subtitles (with transparent option checked) appears and blocks that new tickers with solid black blocks and if I leave the option unchecked, it makes it bit hard to read subtitles from the video screen. With semi-transparent, you can able to catch bit of information going on behind the subtitle. Let me know if there is a way or can't be done.