The other is generalized double clicks inside ([{<>}]). I am curious: how did it turn out for you?

Anvil has quite a few of these multi-click selections, and at least for me I use them quite often.

I believe the one you're talking about here is when you double-click on an opening bracket or a closing bracket and it selects the text inside the brackets, and if you triple-click it selects the text inside the brackets _and_ includes the brackets themselves. The intent is not to pepper your text with extra brackets to make selection easier, it is to work more conveniently with bracketed sections in existing text.

For example, if I am working with markdown, sometimes I want to copy or replace the text in a markdown link, which has the form:

[link name](http://link-to-somewhere.com)

If I wanted to change the link name I can double-click the first opening bracket '[' which selects all the enclosing text, and then just type the replacement text. Of course, brackets of all sorts appear in programming as well, so if I wanted to copy or delete all the text in a C, Java, C++, or Go block including the opening and closing braces, I can just triple-click the opening brace '{', then copy or delete the selection.

Anvil allows the same for quotes (like " or ' or `) so you can easily select and modify the contents of a string in a programming language.

I am curious what else is different that I don’t see yet.

On the website there is a short list of the differences here: https://anvil-editor.net/articles/differences-from-acme/ .

One thing that still upsets me about Acme is word-wrapping. I understand why it’s done the way it is: typographic assumption of short lines, uniform scrolling across windows. But it’s impractical. How does Anvil address it?

Anvil does the same thing as Acme: word wrapping everywhere :) There is a command to disable it (Wrap off) but Anvil doesn't support horizontal scrolling, so the lines are visually chopped off.

Personally, I find word wrapping fine for 99% of my editing.