Re: feature/completions-highlight-modifications e3c5b99 3/6: Add completions-highlight-mode initial implementation.

[Ergus]

Hi Juri:

I made some of the changes you suggested, I think the behavior is a bit
more reliable now. 

On Wed, Nov 18, 2020 at 09:43:28PM +0200, Juri Linkov wrote:
> > The code is extremely simple, so, if you think you could improve
> > anything it is more tan welcome.
>
> The branch contains many different features with different problems,
> so here is a short summary for these 4 separate features:
>
> 1. feature of setting minibuffer-tab-through-completions-function to
>   completions-highlight-minibuffer-tab-through-completions:
>
> The problem is that such TAB cycling is limited only to the case
> when the whole *Completions* buffer is visible.
This was as I said intentional. And to change that could be relatively
easy but I am not 100% we should. Maybe with a custom in the future...

> The original behavior of multiple presses of TAB is limited too:
> its browsing is uni-directional, there is no way to use S-TAB
> to scroll completions backwards.
>
> So I don't see how relying on TAB could improve navigation in completions.
>
> 2. completion-set-suffix sometimes doesn't work;
I think it is fixed now.

> 3. commands that dispatch navigation keys from the minibuffer to the
>   *Completions* buffer: this doesn't cover other navigation keys.
>
> Maybe like windmove-default-keybindings defines modifiers,
> a similar function could set up modifiers for scrolling completions
> from the minibuffer, then the users could choose whether to use
> e.g. 'M-' modifier for scrolling completions, or no modifier at all.
I will try that when have some time.

> 4. the feature of using completions-highlight-overlay often fails to
>   update highlighting when point is moved in the *Completions* buffer
>   by other navigation commands.
>
> To fix this, it could work like hl-line-mode, but instead of
> highlighting the whole line, it could highlight only completions.
Done.

I didn't use the post-command-hook before because I didn't know about it
when I started and then I forgot to fix that. Please give it a try now.

> Then completion highlighting would be useful on its own.
> A new defcustom e.g. 'completion-highlight' (disabled by default)
> could add a post-command-hook like hl-line-mode does.
> Then other completion commands could enable this variable locally.

I made this on the beginning, but I didn't want to add more code to
simple.el...

Maybe not a custom but a minor mode is better and simpler. It is just to
divide my current code in two minor modes instead of just one.

I will consider that...