bug#51210: Customizable other-window-for-scrolling

[Juri Linkov]

>> The right window would be most-recently-used window like can be
>> customized in e.g. compare-windows-get-window-function.
>
> For me, it's always the next-window.  Which explains why you aren't
> satisfied: you expect something else.  So why not have a new command,
> scroll-mru-window?

and

> Wouldn't it be easier to add a new command scroll-other-frame?

It's much easier to customize one variable to the needed function
that to create a dozen of commands and rebind them to the same keys
because there are many commands that will use the new variable:

scroll-other-window bound to M-<next>, C-M-v
scroll-other-window-down bound to M-<prior>, C-M-S-v
recenter-other-window bound to C-M-S-l
beginning-of-buffer-other-window bound to M-<begin>, M-<home>
end-of-buffer-other-window bound to M-<end>
...