1395860 - Dropdown items should keep being highlighted under mouse cursor while scrolling the list

Status: NEW

(Core :: Layout: Form Controls, defect, P3)

Description

[Cristina Badescu [:cbadescu], Experiments QA]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:57.0) Gecko/20100101 Firefox/57.0
Version: 57.0a1, Build ID: 20170831100258

Affected versions:
- Firefox Release 55.0.3 and above

Affected Platforms:
- All Windows
- All Mac
- All Linux

Prerequisites:
- Have latest Firefox release installed.

Steps to reproduce:

1. Start the Firefox browser
2. Go to https://twitter.com/download?logged_out=1&lang=en
3. Click on the first input field.
4. Hover the list with the mouse and scroll down several times.
5. Observe the behavior of the items under the mouse pointer after each scroll.

Expected results:
- When scrolling stops, the item under the mouse pointer is highlighted.

Actual results
- The item under the mouse pointer is not highlighted when the scrolling stops.

Notes:
- Here is a screen recording with the issue: https://goo.gl/PyVTr5 
- This issue is also reproducible on https://www.instagram.com/, https://blogger.googleblog.com/
- I have tested this issue on Chrome and I couldn't reproduce it.