Function save 

pub(crate) fn save(list: &str, shown: &str) -> String

The list written, in its order, as the editor has it (JSON), from the list it showed (shown, JSON; “” for none): the editor’s change set over the filters as the configuration holds them now, under its lock, which the sharing takes too (settings::rebased): a filter another device added meanwhile stays. What went wrong, else “”.