Re: master ce4ec17: Fix display-buffer-override-next-command to call action only once (bug#39722)

[Juri Linkov]

>>> 2. to allow adding arguments to the commands `C-x 4 4` and `C-x 5 5`.
>>
>> That's the problem, indeed.  It introduces two different kinds of
>> prefixes: those that only apply to "normal commands" and those that also
>> apply to (some) prefixes.
>>
>> I'd rather try and avoid this complexity because I think it will become
>> problematic as more prefix commands get written.  E.g. the ordering
>> problem doesn't only affect `C-u` but all other prefix commands, such as
>> `C-x RET c` (there currently aren't others bundled with Emacs, but there
>> are others out there).
>
> Hmm, I didn't know that set-buffer-file-coding-system supports a prefix arg:
> `C-u C-x RET f`.

BTW, there is also a new command 'same-window-prefix' to request
displaying the next command's buffer in the same window to override
the setting that would otherwise display the buffer in another window.

But the problem is that currently it's not bound, and I can't find
a good mnemonic keybinding.

'C-x 4 0' is already taken.
'C-x 4 1' could be reserved for another command that would delete other windows
          before displaying the next buffer in the remaining single window.

Maybe 'C-x 4 s'?