Bug 196497 – REGRESSION (macOS 10.14.4): When scrolling the Twitter timeline page, some tweet's block background color changes to black

• Status: NEW
• Component: Layout and Rendering

[Saulo Pratti]

Created attachment 366497 [details]
Screen recording of the bug on the Twitter timeline

This issue affects specially the Twitter timeline page. Sometimes, when scrolling the page, a tweet block background color changes to black. Hovering the element may change it back to normal.

1) Open a Twitter timeline page. (Used my own timeline, https://twitter.com/@blude)

2) Scroll down the page. (Keep the mouse pointer away from the main timeline region)

The tweet content blocks have a `:hover` selector used to change its background color to light-gray.

Some rare blocks, anecdotally ones with rich media displayed, will have its background color changed or flashed to black when scrolling.

The tweet blocks should retain its normal background color.

Hovering the mouse pointer into the affected block will revert the background color to its correct style. 

This issued was not noticed in macOS Safari version prior to 12.1

The attached video file has a screen recording of the issue.

[Saulo Pratti]

Created attachment 366498 [details]
Screen recording of the bug on the Twitter timeline

[Simon Fraser (smfr)]

What hardware do you see this one (including graphics/screen configuration)?

[Saulo Pratti]

Hardware is a MacBook Pro (Retina, 15-inch, Mid 2015)

[Saulo Pratti]

Hardware is a MacBook Pro (Retina, 15-inch, Mid 2015)

General
=======

  Model Name:	MacBook Pro
  Model Identifier:	MacBookPro11,4
  Processor Name:	Intel Core i7
  Processor Speed:	2,2 GHz
  Number of Processors:	1
  Total Number of Cores:	4
  L2 Cache (per Core):	256 KB
  L3 Cache:	6 MB
  Memory:	16 GB
  Boot ROM Version:	189.0.0.0.0
  SMC Version (system):	2.29f24


Graphics
========

Intel Iris Pro:

  Chipset Model:	Intel Iris Pro
  Type:	GPU
  Bus:	Built-In
  VRAM (Dynamic, Max):	1536 MB
  Vendor:	Intel
  Device ID:	0x0d26
  Revision ID:	0x0008
  Metal:	Supported, feature set macOS GPUFamily1 v4
  Displays:
Color LCD:
  Display Type:	Built-In Retina LCD
  Resolution:	2880 x 1800 Retina
  Framebuffer Depth:	24-Bit Color (ARGB8888)
  Main Display:	Yes
  Mirror:	Off
  Online:	Yes
  Rotation:	Supported
  Automatically Adjust Brightness:	No

[Saulo Pratti]

Created attachment 366574 [details]
System Profile full

Full system profile generated by system report

[Radar WebKit Bug Importer]

<rdar://problem/49565685>