Blank screen, UI lock

[Ragada]

Hi, I would like to find two features in VLC, please help.

1. How can I turn on a subtitle for a mp3 or any other audio file without audio visualization?
If Audio visualization is disabled subtitle doesn't appear on the screen. I would like to watch subtitles for audio files without Scope, Spectrum or any other visualization. Just on a blank black screen.
(If you can give information how can I develop my own visualization for audio files that is also perfect.)

2. How can I lock the screen during I'm watching a movie? If I move my mouse UI controls always come.
I would like to use my mouse only for the increase or decrease volume without VLC shows the UI controls (If I can turn off the volume bar as well that is the best.).