RE: Exposing Isearch toggleable options

[Drew Adams]

> The discoverability issue is a very interesting one. Even more when
> combined with ergonomics and convenience in general. Not too long ago I
> was surprised to see how discoverability *and* convenience are benefited
> from having a good completion mechanism on the M-x and set-variable
> prompts. Ido+flx was a big enhancement for a tiny effort, IMO. I'm sure
> that other packages can bring similar or superior benefits.
> 
> Ido+flx work on command/variable names. It would be better to have
> conceptual relations among features, and exploit those relations
> contextually. Some type of smart search engine for features, with the
> right interfaces.

FWIW: Icicles provides this for all minibuffer completion, not
just for command and variable names.  It also provides all of
the keys available in the current dynamic context, including after
you hit prefix keys.  (And you can invoke the completed keys -
any number of the key-completion candidates.)

By default, it automatically provides short help in the mode line
for the "current" completion candidate (you can cycle candidates
or otherwise choose any as the "current" one).  And you can hit
a key to get the complete help for the current candidate, in *Help*.

For example, for `M-x', the candidates are command names.  Cycling
among those that match your current minibuffer input, as each is
cycled through, one-line help is shown for it in the mode line.
And if you hit `C-M-RET' then the complete `describe-function'
help for it is shown in `*Help*'.

Same thing for faces (using `describe-face'), packages,... whatever.

Same thing for key completion: the available keys (at top level or
after a prefix key) are completion candidates, and their help too
is available in the mode line and (on demand) in *Help*.

So yes, I agree that discoverability is radically helped by
providing help on completion candidates.

And extending this to keys is particularly helpful.  Emacs lets
you know what you can do at any time, and lets you find out more
and more about what's possible, on demand, on the fly.  (You can
access the manual from *Help*...)