bug#48754: previous-line on large lines or images travels two lines sometimes

bug#48754: previous-line on large lines or images travels two lines sometimes

[Radon Rosborough]

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I've encountered some puzzling behavior related to
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=48170.

Specifically, running under emacs -Q commit
d6dc66053d846b6fc041889b4d0f383c8dac4da3 of 2021-05-30 on GNOME, if I load
up https://github.com/raxod502/bug48170-repro, then `next-line' navigates 1
line down, but `previous-line' navigates 2 lines up!

Any ideas about what might be causing that?

Best,
Radon

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bug#48754: previous-line on large lines or images travels two lines sometimes

[Eli Zaretskii]

> From: Radon Rosborough <radon.neon@gmail.com>
> Date: Sun, 30 May 2021 14:54:34 -0700
> 
> I've encountered some puzzling behavior related to https://debbugs.gnu.org/cgi/bugreport.cgi?bug=48170.
> 
> Specifically, running under emacs -Q commit d6dc66053d846b6fc041889b4d0f383c8dac4da3 of
> 2021-05-30 on GNOME, if I load up https://github.com/raxod502/bug48170-repro, then `next-line' navigates 1
> line down, but `previous-line' navigates 2 lines up!

I cannot reproduce this.  With the current master, both C-n and C-p
move by one screen line.

P.S. I only downloaded code.el, and it seems identical to the one in
the previous bug.  the images seem also identical, so I reused the
images from the previous bug.  Did any of them change?  Judging by the
time stamps, they didn't.

bug#48754: previous-line on large lines or images travels two lines sometimes

[Radon Rosborough]

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I've found that this problem appears to depend on the window size. With the
default window size, everything works as expected. But, when I maximize the
window to fill my screen, C-p moves two lines up. Does that happen for you?
If not, I can experiment to find more precise conditions.

code.el is the same as the previous report, yes.

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bug#48754: previous-line on large lines or images travels two lines sometimes

[Stefan Kangas]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Radon Rosborough <radon.neon@gmail.com>
>> Date: Sun, 30 May 2021 14:54:34 -0700
>>
>> I've encountered some puzzling behavior related to https://debbugs.gnu.org/cgi/bugreport.cgi?bug=48170.
>>
>> Specifically, running under emacs -Q commit d6dc66053d846b6fc041889b4d0f383c8dac4da3 of
>> 2021-05-30 on GNOME, if I load up https://github.com/raxod502/bug48170-repro, then `next-line' navigates 1
>> line down, but `previous-line' navigates 2 lines up!
>
> I cannot reproduce this.  With the current master, both C-n and C-p
> move by one screen line.

I can reproduce this bug on current master.

Here's the git clone command for the sake of convenience:

    git clone https://github.com/raxod502/bug48170-repro.git