1519983 - https://forums.lenovo.com is cycling during scrolling

Status: NEW

(Core :: Layout: Scrolling and Overflow, defect, P3)

Description

[Stefan [:StefanG_QA]]

Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:66.0) Gecko/20100101 Firefox/66.0 (20190114104248)

STR:

1. Launch Firefox
2. Go to https://forums.lenovo.com/t5/Motorola-Community/ct-p/MotorolaCommunity
3. SLOWLY scroll down just a bit
4. Observe scroll bar cycling

AR: The scroll bar is cycling once you start scrolling
ER: Solid scroll position

The issue does not reproduce with scroll anchoring set to false.

Short video of the issue can be seen here: https://St3fQA.tinytake.com/sf/MzIyODM3N185Njc0MDcw

Comment 1

[Ryan Hunt [:rhunt]]

I can also reproduce this in Chrome.

The issue is that this case isn't covered by the normal adjustment suppression logic.

We have two sets of elements that are toggled between based on scroll offset.
1.
a. <div style="display: none"/>
b. <div style="position: static"/>
2.
a. <div style="position: fixed"/>
b. <div style="display: none"/>

So we never have an element transition between being in-flow to being out-of-flow, as (a) transitions between not being visible and being in-flow, and (b) transitions between being not visible and being out-of-flow.

The spec and both our implementations monitor when elements go between in-flow and out-of-flow, and suppress adjustments then.

I think we could fix this, but because Chrome has this issue as well we don't need to before shipping.

Comment 2

[jolly]

I also use the lenovo laptop and I have a issue in my site of https://thaiharempants.net/category/bohemian/