Regions are matched greedily, not recursively

[lenormf]

Consider the same context as in #3055, adding this time matching nested scopes i.e. $(… $(…)…).

This issue probably also depends on #3055.

Steps

Same as in #3055.

Outcome

If #3055 were fixed, only the opening and closing delimiters of the region would be matched.

Expected

Regions are detected as being nested, and so all opening and closing delimiters are highlighted.

It's my understanding that when regions are nested, only the one with the largest scope (which contains the nested scopes) will be highlighted, which makes relying on \A and \z moot.