Re: completing-read does not display options in new frames

[Eli Zaretskii <eliz@gnu.org>]

> From: Ma Gelan <magel4n@gmail.com>
> Date: Mon, 1 May 2023 12:52:09 +0900
> Cc: help-gnu-emacs@gnu.org
> 
> I feel that I did not explain my issue well.
> 
> I tried this: emacs -Q -l test.el
> 
> With test.el having the code.
> 
> What I get is two emacs frames. The main frame is on *scratch* buffer,
> and the other frame is just a miniframe. If I focus the miniframe I get
> the 'Select:' prompt, no options are shown. I expect to see a list of
> vertical options but they only show if I press tab. In this case they
> show in the other window, because that is the vanilla behavior in emacs,
> but In my version I have the completion directly in the minibuffer. In
> both cases, my configuration and emacs -Q, the options do not show right
> away, which means that I have to actively press Tab to show them.
> 
> My question is: How do I show the options without having to press Tab?

You can't, not with the default vanilla completing-read behavior.

You need to understand the concept behind the default Emacs completion
scheme.  It was devised for users who (a) are very fast typists, and
(b) know very well what they want to type, so they don't need any
hints before they start typing.  What they do need is TAB-completion
so that they could type only a small part of input, and have the rest
completed by Emacs for them.

Therefore, there are no completion candidates shown unless you ask for
them, by typing TAB.

> I would like to see them listed as soon as the minibuffer shows up.

Then you need a non-default completion behavior, like ibuffer or
similar.