bug#43519: 28.0.50; Overlay at end of minibuf hides minibuf's real content

[Gregory Heytings via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

>>> The solution I proposed in my other message (assuming that it is 
>>> accepted) is more general, I think.
>>
>> If you mean "to start the display at the beginning of the screen line 
>> where we end up after move_it_vertically_backward returns", it is IMO 
>> worse.
>
> I think you misunderstand my proposal, because the beginning of the 
> screen line where we end up in the use case we are discussing is the 
> BOB.
>

I'm not sure they are, but I'm not an expert.  If they are, then of course 
your proposal would be okay.

The purpose of the discussion (AFAIU) is to introduce a change to make it 
possible for icomplete/ido/... to put a too long overlay at EOB (with say 
two or three more candidates than can be displayed in the mini-window), in 
such a way that the prompt will always be displayed, and the last part of 
the overlay will not.  What happens with your proposal when 
max-mini-window-height is 10, and the overlay needs 13 lines?  What 
happens when max-mini-window-height, the overlay needs 10 lines, and the 
prompt and user input so far need two lines?