>> BTW, while looking at windows walking functions, I noticed
>> an opportunity for simplification.
>>
>> Martin, could you please confirm if I'm not mistaken with this patch:
>
> Removing the
>
>     (when (framep all-frames)
>       (select-window (frame-first-window all-frames) 'norecord))
>
> LGTM.  Whether we should remove the
>
>   (save-selected-window
>
> envelope is another question.  If FUN changes the selected window,
> we'd now have a side effect we didn't have so far.

So I left a comment explaining why save-selected-window is still needed.

Now I prepared a patch for dired-dwim-target to DWIM most recently used
windows from all frames: