1513602 - scrollbar-color CSS property not always respected on Mac

Status: RESOLVED WONTFIX

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

Description

[Michael]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:64.0) Gecko/20100101 Firefox/64.0

Steps to reproduce:

Upon visiting the MDN article on CSS scrollbars (https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Scrollbars), I noticed that the example did not show any effect on my Macbook Pro.  Visiting the page again on my Windows machine showed the expected changes.


Actual results:

On my Macbook, there is a setting under System Preferences > General called "Show scroll bars."  This settings has three options:

1. Automatically based on mouse or trackpad
2. When scrolling
3. Always

If either of the first two choices are selected, the scrollbar-color CSS is ignored.


Expected results:

Regardless of the setting, I would expect the CSS property to color the scrollbars.  At a minimum, I believe the MDN article should mention this quirk.

Comment 1

[Chris Mills [:cmills]]

FYI, I removed the warning box you added to the scrollbar-color page, and represented it as a note in our browser compat data repo instead:

https://github.com/mdn/browser-compat-data/pull/3204

This will show up on the page as desired once merged and when we release a new package.

Comment 2

[Michael]

Thank you!

Comment 3

[Paul_B]

User Agent:Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:64.0) Gecko/20100101 Firefox/64.0 

Hello,

Thank you for taking the time to add this report.

I verified this on the latest Firefox version builds (Release - 64.0/20181206201918; DevEdition - 65.0b4/20181211223337 and Nightly - 66.0a1/20181217000148) and the scroll bar is colored when the 1st and 3rd options are selected. When the 2nd option is selected ("When scrolling"), the scrollbar is gray. 

Is this expected or should we also display the scroll bar colored for the 2nd option?

Comment 4

[Emilio Cobos Álvarez (:emilio)]

I assume that ni? was for the other cmills :)

Xidorn, do you know if this is known?

Comment 5

[Xidorn Quan [:xidorn] UTC+11]

Yes, this is known, and actually intentional.

Custom scrollbar colors are not applied when overlay scrollbar is used on macOS, which is exactly the situation described in comment 0.

The reason of doing so is:
* that overlay scrollbars look good regardless of environment, unlike others
* it's harder to simulate the native overlay effect with custom impl so it may not be worth that effort to do so

Comment 6

[Xidorn Quan [:xidorn] UTC+11]

I would call it WONTFIX for now. We may revisit it if we decide the other way. If someone volunteers to implement the overlay scrollbar with custom colors, feel free to reopen this bug and do so. I believe this is doable, just didn't think it justifies the effort.