Eli Zaretskii wrote:

>     explanation is correct, I'd need to see the artifacts when the
>     underlying window is full of some buffer text, not almost empty as
>     in *scratch*.  Glenn, could I persuade you to try that and show
>     the screenshots?

See 1.png.

> cause significantly more cursor motion.  One possible way to cut down
> on that is to set show-help-function to nil.  Glenn, can I ask you to
> try that and see if it helps in any way?

It does not help.
See 2.png. It leaves my screen like 3.png after closing the menu.