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

[Stefan Monnier]

> The feature was intentionally designed this way for several reasons:
> 1. it should be easier for the users to build the key sequence
>    when the prefix is in front of the main command key sequence,
>    not before the command that requests a new window/frame;

I don't think supporting only one of the two orders can be claimed to
make things easier for the user.

> 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).


        Stefan