Bug: Line number in code snippets doesn't stay on the left side when scrolling

[Manueljlin]

Summary

On long snippets of code like in here, if you scroll horizontally using a touchpad or (more noticeably) with a mouse wheel + shift, the small line number indicator gets detached from the left side

Where did you spot the bug?

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter

Steps to reproduce the issue

1. Open an entry with a longer code snippet like https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter
2. Resize window until the content flows out of the view and the scrollbar appears
3. Scroll horizontally with mouse wheel + shift or with a touchpad

Happens with a 1080p 16:9 screen with the window sized 50vw so it's probably even more noticeable for sub-1920w screen

Environment

Device

• Desktop
• Mobile: ...
• Tablet: ...
• Other: ...

Browser

• Chrome: (what version?)
• Firefox: (97.0.1)
• Safari: (what version?)
• Other: (what browser / version?)

Operating system

• Windows: (what version?)
• Mac OS: (12.6)
• Linux: ( openSUSE Tumbleweed / 2022 02 28 )

Screenshots

https://youtu.be/WZV_xQaCNqk

[caugner]

@Manueljlin I can no longer reproduce this issue. Could you please try again to see if you still have it?

[Manueljlin]

Well, this is weird.
When I'm not recording the screen, I can't reproduce it anymore with the external computer mouse, and only just slightly with the trackpad. The moment I do start recording though, it appears again.

Here's more detailed information:

KDE Plasma Version: 5.24.4
KDE Frameworks Version: 5.93.0
Qt Version: 5.15.2
Kernel Version: 5.17.3-1-default (64-bit)
Graphics Platform: X11
Processors: 8 × Intel® Core™ i7-10510U CPU @ 1.80GHz
Memory: 15.4 GiB of RAM
Graphics Processor: Mesa Intel® UHD Graphics

Firefox: 99.0.1 (64-bit)

IIRC, I could reproduce it on a windows machine at school too, which might be easier to grab info from than to fight all of the opensuse downstream patches, xorg, kwin, nvidia stuff

[Manueljlin]

Just remembered about this one. More info:

• Can reproduce with macOS 12.6 on an M1 Mini with a regular mouse + Shift and with the mouse's horizontal scroll wheel click thing (Logitech M720). Not exclusive to Linux, but that's not really surprising.

• Only happens with Firefox (in this case 105.0.1), not on Chrome or Safari.

I'll try on an M1 iMac + Magic Trackpad tomorrow and try to add more details for touchpads since I don't have the laptop from the previous comment anymore.

[caugner]

Closing in favor of #976.

[Manueljlin]

I /think/ that's a different bug that just happens to also be for the line indicator

[caugner]

@Manueljlin Would you be able to share a full-screen video of the steps to reproduce this issue?

[Manueljlin]

Ok, here's a few more videos, this time macOS Monterey on M1 Mini. As for the steps, just scroll with a mouse while holding shift to move horizontally.

macos-firefox-recording.mp4

macos-chrome-recording.mp4

macos-safari-recording.mp4

It only happens with Firefox, it seems. Upstream issue? :D

[caugner]

Thank you so much for those videos. I noticed that in the Chrome/Safari videos you scroll using the scrollbar, was that intended?

It only happens with Firefox, it seems.

Could you please try again with Troubleshoot Mode (Help > Troubleshoot Mode)?

PS: I was able to reproduce a tiny artifact in Firefox 109.0a1 on Mac OS (Intel) when horizontally scrolling using Shift + mouse scroll:

Screen.Recording.2022-11-16.at.11.14.25.mov

[Manueljlin]

I scrolled with both the scroll bar and mouse wheel in all videos to show that with the scroll bar it can't be reproduced on any of them, including Firefox. What I didn't notice is that in the latter two videos I use the scroll bar first unlike the first one 😅

With chrome I start using the scroll wheel 10 seconds in. In safari 5 seconds in.

I'll try with the troubleshoot mode later today, and also update the Firefox version from the bug report to the current one

[NiedziolkaMichal]

@Manueljlin Could you please check if this issue is now resolved?

[Manueljlin]

Yeah, it's solved :D Thanks!