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>]

For some reason I did not receive a copy of your mail.  I see it now.

>
>  . Fix these problems on the application level.  In the case in
>    point, that would mean for icomplete.el to augment its
>    calculations of where to truncate the list of candidates so that
>    the problem doesn't happen (and AFAICT it doesn't happen if the
>    stuff to be displayed in the mini-window fits the mini-window
>    after resizing it to max-mini-window-height).
>

It is difficult to fix such problems on the application level.  If the 
stuff to be displayed in the mini-window fits the mini-window after 
resizing it to max-mini-window-height, the problem does not happen indeed. 
But the difficulty is precisely to create the stuff to be displayed in 
such a way that it fits the mini-window, because it can use a font that is 
not the default one, it can have embedded newlines, it can contain lines 
that are too wide for the mini-window, and so forth.

>
>  . Define in more detail what situations we would like to fix in the
>    display code, so that we could install special ad-hoc changes
>    there to handle those situations.  For example: is it true that in
>    all of these situations starting the mini-window display at BOB
>    would DTRT?  If so, I think this could be arranged.  If not, why
>    not, and what is the more correct definition of the situations we
>    want to handle?
>

See my proposal, which does exactly this.  Yes, it is true that in all of 
these situations starting the mini-window display at BOB would do the 
right thing.

>
> IOW, the basic logic is to show the last max-mini-window-height screen 
> lines of what's in mini-window.
>

Yes, and this is not desirable in certain cases, it should be possible to 
show the *first* max-mini-window-height screen lines of what's in 
mini-window.