bug#66948: [PATCH] Add Completion Preview mode

[Juri Linkov]

>>> While testing more, I noticed one strange thing,
>>> I don't know if it's intended to work this way.
> [...]
>> This appears to be a general problem with `completion-in-region-mode`,
>> that it keeps TAB bound to `completion-at-point` after a partial
>> completion, so I don't think we should attempt to handle it in
>> `completion-preview` specifically.
>
> Let me know if you think otherwise, that `completion-preview` should
> handle this case specifically, although I'm pretty convinced that it's
> the behavior of `completion-in-region-mode` that's not quite right here.

This looks like a problem of `completion-in-region-mode` indeed.

> Either way, I'm attaching an new patch (v3) that includes
> `backward-delete-char-untabify` in `completion-preview-commands` to
> provide a nicer OOTB experience for Elisp (as you suggested), along with
> a couple of minor optimizations and documentation improvements.

Let's see what Eli decides to do with your new package.