Clash between selection background and matching parens highlight

I have selected only the function parameters, but it looks as if I had selected the parens as well:


This makes editing a bit confusing.

Reproduce the reported selection of function parameters while matching-parenthesis highlighting is visible in the editor. Trace the editor's selection and matching-paren rendering paths, then verify that selected parameters and highlighted parentheses are visually distinguishable without changing either behavior.

Written by the indexing model from the issue text.