bug#41890: bug#42210: bug#41890: 28.0.50; [PATCH]: Add bindings for project.el

[Juri Linkov <juri@linkov.net>]

>> While the prompt is active, the key '?' and 'C-h' could (and I think should)
>> display a list of *ALL* available key bindings from the project keymap
>> in the *Help* buffer (like e.g. 'query-replace' does after typing 'C-h').
>
> What would determine which of the bindings get shown in the prompt,
> then, supposing there were too many to fit them all?

Maybe it's possible to show all them by using 'read-char-choice' when only
the initial letters are displayed in the prompt like "(f, g, d, v, s, ?): "
or using 'read-answer' or 'read-multiple-choice', e.g.:

(read-multiple-choice "Select project"
                      '((?f "Find file")
                        (?g "Find regexp")
                        (?d "dired")
                        (?v "vc-dir")
                        (?s "shell")))

>>> I do think we should avoid binding commands under C-x 4 where the
>>> versions under C-x p would already display in another window -- I think
>>> it is potentially quite confusing to have bindings with identical
>>> behaviour under both C-x 4 p and C-x p.
>>
>> Shouldn't some key sequence force displaying the project buffer in the
>> same window (when a version under C-x p displays it in another window)?
>
> It's hard to know what key sequence to use.

Indeed, it's hard to find a key prefix analogous to 'C-x 4 1'.
Maybe 'C-x 4 1 p'?