bug#74246: [PATCH] Reuse display windows in image-dired

[Juri Linkov]

>> I agree with the need to set the window parameter always.
>> For example, I often use commands that override the default action
>> with e.g. windmove-display-up/down, etc.  Therefore needed
>> to add an advice that remembers the last window in the
>> buffer-local variable:
>>
>> (defvar-local display-buffer-last-window nil)
>
> Let's define it via DEFVAR_PER_BUFFER in buffer.c and have
> 'window--display-buffer' always set it.
> 'display-buffer-use-some-window' then could use it either by default or
> if it finds a 'some-window' entry whose cdr is nil or t or whatever we
> want.
>
>> However, I still like your proposal to use a category instead of lru,
>> that could be used here later as well.
>
> With 'image-dired' 'display-buffer-last-window' wouldn't help.  But
> 'image-dired' could define a mode-local variable, say
> 'image-dired-last-window', and propose that as 'some-window'.  We could
> make 'some-window-method' accept a live window for that purpose.

Please explain why 'display-buffer-last-window' wouldn't help
for 'image-dired'?  IIUC, 'image-dired' uses one source buffer
that could use the buffer-local variable to remember the last
window it used to display an image buffer.