1377658 - right sidebar on CNN jumps up and down at ~30fps (Nightly 56 only)

Status: RESOLVED INCOMPLETE

(Core :: Layout, defect, P3)

Description

[Randell Jesup [:jesup] (needinfo me)]

In the last week-ish on Nightly, the right sidebar on CNN pages tends to jump up and down as you scroll, often flickering back and forth at ~30fps even when the scrollbar isn't being touched.  On this article (http://www.cnn.com/2017/06/30/architecture/rome-ruins-metro-excavation/index.html) it does it for me (win10, maximized window, Lenovo P50) when scrolled to where "The charred remains of a lavish third-century home" are near but not quite at the top of the scrolling area.  You might need to play around with positioning of the scrollbar to see the continuous flicker, but it will happen in many positions.

Not sure it's a layout bug, but seems reasonable to start.

Comment 1

[Mike Kaply [:mkaply]]

I can recreate on 55 as well.

Comment 2

[Mike Kaply [:mkaply]]

I can recreate as far back as Firefox 45. It only happens with the taller ad which is why it is harder to recreate. It is not flash related.

It has to do with CNN trying to move the top stories down when you scroll, but there isn't enough room because of the larger ad.

It does work on Chrome.

Comment 3

[Daniel Holbert [:dholbert]]

Calling this "wontfix" for 57 (current beta), since it's not a regression, not crazy-severe, and doesn't seem like it'd be a low-risk fix.

Comment 4

[Daniel Holbert [:dholbert]]

(er, not a *recent* regression at least, per comment 2)

Comment 5

[Randell Jesup [:jesup] (needinfo me)]

no longer occurs that I notice.