Re: Emacs completion matches selection UI

[Juri Linkov <juri@jurta.org>]

> The completion system is fine.  The selection of matches is the problem:
>
> 1) see a new buffer popup with minimal help text and no highlighting
> 2) left, right, up, down don't work
> 3) realize problem, switch to candidates buffer (mouse click or `C-x o')
> 4) select candidate you want, get popped in original buffer
>
> That's not simple!  It's not intuitive either, forcing me to use the
> mouse unless I've read the manual node referenced above.
>
> An alternative UI doesn't have to be fancy or graphical, only allow me
> to select from among the candidates immediately, without switching
> buffers, using the intuitive keys.  I hope that explains my request better.

In modern UIs, auto-completion works such a way that after you type text
it pops up a drop-down menu with a list of candidates where you can
select one by using <down> and <up> arrow keys.

How this could map to Emacs?  The first difference is that in Emacs
the text entry field (the minibuffer) is at the bottom of the screen,
so the drop-down menu should pop up upwards using the display-window
property `near-minibuffer' (this will display completions nicely aligned
with the contents of the minibuffer).

Another difficulty is that in the minibuffer <up> and <down> arrow keys
are bound to previous-history-element and next-history-element,
so they can't be used to select an element from the list of candidates.

One solution is to automatically display the list of completions
when the user starts typing in the minibuffer and allow <up> and <down>
to navigate the list of completions if the minibuffer contents is not empty.
Otherwise, <up> and <down> will browse the history.

Since this is quite obtrusive change it might require special mode
much like ido-mode but closer to auto-completion provided by other
GUI applications.