bug#57349: 29.0.50; pixel-scroll-precision-mode. error integer-or-marker-p nil

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

Gerd Möllmann <gerd.moellmann@gmail.com> writes:

> Po Lu <luangruo@yahoo.com> writes:
>
>>
>> Gerd Möllmann <gerd.moellmann@gmail.com> writes:
>>
>>> In GNU Emacs 29.0.50 (build 1, aarch64-apple-darwin21.6.0, NS
>>>  appkit-2113.60 Version 12.5.1 (Build 21G83)) of 2022-08-22 built on
>>>  Mini.fritz.box
>>> Repository revision: 0c410206aa91b9bc9a0922d63ec34de765eb86a6
>>> Repository branch: master
>>> Windowing system distributor 'Apple', version 10.3.2113
>>> System Description:  macOS 12.5.1
>>>
>>> emacs -Q
>>> M-x pixel-scroll-precision-mode RET
>>>
>>> Move the mouse to the lower right corner of the Emacs frame.  On macOS,
>>> the mouse cursor changes shape to a double-arrow pointing 45 degrees in
>>> the direction of the upper-left and lower-right corner of the screen.
>>>
>>> Scroll the mouse wheel.
>>>
>>> This either prints messages like this
>>>
>>> <nil> <wheel-up> is undefined
>>> <nil> <double-wheel-up> is undefined
>>> <nil> <triple-wheel-up> is undefined [45 times]
>>> <nil> <wheel-down> is undefined
>>
>> I think that's the internal border.
>>
>>> or sometimes errors 'Wrong type argument: integer-or-marker-p, nil'.
>>> Not sure what to make of this.  Looks like posn-at-x-y returns a posn
>>> with a nil point?  Or maybe posn-point returns nil?
>>
>> Probably the former.  Could you please see if that error reliably shows
>> up if you scroll with the mouse pointer over the place where the right
>> fringe overlaps with the right and bottom internal borders?
>
> I'm not quite sure.
>
>    ...text | fringe | scrollbar | something |
>    -------------------- modeline ------------
>    ...text | fringe | scrollbar | something |
>
> Sp far, I couldn't produce the error anywhere when the mouse is above
> the modeline.  It's just saying that 'nil something' is undefined.
>
> Below the modeline, it's happening when being in 'fringe', 'scrollbar'
> 'something' AFAICT.  Sorry, it's a hard to move the mouse precisely, and
> the rounded edge of the frame doesn't help either.
>
> I think this shows one of the events leading to the error:
>
>   pixel-scroll-precision-scroll-up-page(0)
>   pixel-scroll-precision-scroll-up(1)
>   pixel-scroll-precision((wheel-up (#<window 4 on  *Minibuf-0*> vertical-scroll-bar (576 . 8) 137763384 nil 1 (81 . 0) nil (576 . 8) (15 . 16)) 1 0 (0.0 . 1.0)))
>   funcall-interactively(pixel-scroll-precision (wheel-up (#<window 4 on  *Minibuf-0*> vertical-scroll-bar (576 . 8) 137763384 nil 1 (81 . 0) nil (576 . 8) (15 . 16)) 1 0 (0.0 . 1.0)))
>   command-execute(pixel-scroll-precision)

That's pretty odd, I can't reproduce the problem at all.  The next time
I get access to a Mac (it may be a while) I will see if it can be
reproduced there.

Thanks.