bug#70856: 30.0.50; Hang when scrolling the echo-line with pixel-scroll-precision-mode

[Po Lu]

Steven Allen <steven@stebalien.com> writes:

> I think the fix is a little more complicated because, while a window may
> be 1 line tall, the underlying buffer may have more than one line.
>
> I believe we need two changes.
>
> 1. In `pixel-scroll-precision-scroll-down` and `-up`, set `max-height`
>    to a minimum of `1` (pixel). It looks like someone already "fixed" the
>    `-up` variant, but I'm not sure that that "fix" is correct as it
>    prevents scrolling in a 1-line window.
> 2. Disable `pixel-scroll-precision-mode` in the echo area and
>    minibuffer? It does not behave well in either case.
>
> But I'm not sure. I'm happy to submit a patch if this sounds like the
> right approach.

I've fixed this on master, please test and ack.