Re: [PATCH] (icomplete-vertical-mode): Add support for affixations and, annotations

[Juri Linkov]

> Do you mean we cannot handle something like a tabular layout where
> annotations can be resized on the UI level.

Exactly.  What I'm trying to do is to use tabulated-list
in the completions buffer.  Your recent refactoring to
completion--insert-* was a big improvement.

Now we have several rendering functions in the default frontend:

1. completion--insert-horizontal
2. completion--insert-vertical
3. completion--insert-one-column

The next step would be to allow the option 'completions-format'
to accept an arbitrary frontend rendering function.  Then a new
possible value could be added such as:

4. completion--insert-multi-column

So when affixation-function will return a list of multiple columns,
e.g. for buffers the same list of columns as used by list-buffers:
'("C" "R" "M" "Buffer" "Size" "Mode" "File") from the backend,
the new frontend rendering function completion--insert-multi-column
will accept such a list of all columns, set it to the buffer-local
variable 'tabulated-list-entries', and call 'tabulated-list-print'
to render it in the output buffer *Completions*.

Such design would follow a clean backend/frontend separation that
everyone already agreed about.