[Feature Idea] Dim the rest and keep only the syntax highlighting for the same code block

[LintaoAmons]

like, OpenScratch function is highlighted in the outline, so it would be great if there's a option to dim the rest to only have the syntax highlighting for the same context of code block.

[stevearc]

That's a neat feature idea. I would review a PR for this. You may be interested in twilight.nvim