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

[Drew Adams]

> > Cycling is actually a fairly inefficient, unconscious
> > way to navigate among candidates.  It's handy, but
> > dumb cycling shouldn't be the only or the main way to
> > get around.
> 
> I agree.  I tried the completions-highlight-modifications branch, but
> unfortunately restricting a set of navigation keys limits the freedom
> of using any navigation key for browsing completion candidates that is
> available today.  What I mean is that currently it's possible in the
> minibuffer to type <PageUp> (switch-to-completions), and then all keys
> are available for selecting a completion: arrow keys, page scrolling
> keys - even completion drop-down combo in browser's address bar allows
> page scrolling.

I expressed that (and meant it) generally.  But in
particular I meant that the real power of completion
(matching/filtering) is your friend.  Cycling is
handiest when combined with that.  (And in particular
when combined with progressive completion.)
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As for navigating among candidates, cycling is fine
if you also have an easy way to get directly to a
given candidate (and so restart cycling from there).

As for scrolling, in Icicles the usual `C-v' and
`M-v' scroll *Completions*.  It was always misguided
for vanilla Emacs to use TAB for that, IMO.
___

And yes, there should be keys to toggle the input focus.

Icicles uses `C-insert' to move the cursor back and
forth between the minibuffer and *Completions*.  It
moves between the current candidate in the minibuffer
(from cycling) to/from the same candidate in
*Completions*.

Likewise, to move back & forth between the minibuffer
and the buffer from which you activated the minibuffer.
Icicles uses the `pause' key for that.  This lets you
interrupt completion to search, edit, etc. in the
original buffer, without needing a recursive edit.
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https://www.emacswiki.org/emacs/Icicles_-_Moving_Between_the_Minibuffer_and_Other_Buffers