Hello, this feature request is related to #8243 and #8462 .

Expected behavior of the wanted feature

Currently it is possible to toggle the subtitle visibility of both subtitles with subtitle-visibility and of the secondary subtitle assuming subtitle-visibility is set to yes.

For my use case ( https://github.com/fxmarty/rikai-mpv ), I want to make invisible the first subtitle, but to still have the ability to toggle the secondary subtitle visibility. This is currently not possible due to the note in the documentation: https://mpv.io/manual/master/#options-secondary-sub-visibility

Do you think it would be possible to add an option for toggling off/on only the first subtitle while leaving the secondary one untouched?

Many thanks for your hard work!