Re: on helm substantial differences

[Juri Linkov]

> In particular, you can change the *Completions* display on the fly

It would be nice if in addition to already existing 'annotation-function'
'completing-read' also supported 'format-function' or 'display-function',
i.e. a function that would return a completion candidate to display
in the *Completions* buffer.  This will allow completions to use
the same format that is typical to a package's default format, e.g.
typing TAB in the 'C-x d' minibuffer could display completions in the
the *Completions* buffer in Dired format:

  Click on a completion to select it.
  In this buffer, type RET to select the completion near point.
  Possible completions are:
  -rw-rw-r-- 1   185,205 2020-11-14 21:52 minibuffer.el
  -rw-rw-r-- 1     8,386 2020-11-14 21:52 minibuf-eldef.el
  …

'M-x package-install RET a TAB' could display completions in 'package' format:

  Click on a completion to select it.
  In this buffer, type RET to select the completion near point.
  Possible completions are:
  ada-mode       7.1.4     available   gnu   major-mode for editing Ada sources
  ada-ref-man    2020.1    available   gnu   Ada Reference Manual 2012
  …

'C-x b' - completions with the format of 'list-buffers', etc.