bug#42532: 28.0.50; Can eldoc-prefer-doc-buffer be more aggressive?

[Felician Nemeth]

>> Regardless, I think it's reasonable to add a third possible value 
>> for eldoc-prefer-doc-buffer (which should really be renamed 
>> eldoc-echo-area-prefer-doc-buffer).  The value could be the symbol
>> 'aggressive or 'aggressively.  Then it would behave as you propose:
>> if the ElDoc doc buffer is showing, the echo area display code is 
>> a noop.
>>
>> What do you think?
>
> Instead of an abstract idea, here's an actual patch you can try on top
> of the current eldoc.el
> [...]

Thank you.  I've finally tried the patch out with different settings of
eldoc-echo-area-prefer-doc-buffer and eldoc-echo-area-use-multiline-p.
It works as I wished when eldoc-echo-area-prefer-doc-buffer is
'aggressively.  And it works in line with the documentation in most
cases.  However, if I understand the documentation correctly, it doesn't
work as intended with

   (setq eldoc-echo-area-use-multiline-p nil)
   (setq eldoc-echo-area-prefer-doc-buffer t)

For example, with the attached file, moving the point right after "emacs
-Q --load ./bug.el" displays the truncated documentation in the echo
area, but it shouldn't.

bug.el
Description: