1440237 - scrollbar prevents click

Status: NEW

(Core :: Widget: Cocoa, defect, P3)

Description

[Attila Soki]

Attachment: testcase-scrollbar-prevents-click.html

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:60.0) Gecko/20100101 Firefox/60.0
Build ID: 20180221220150

Steps to reproduce:

1. open the testcase "testcase-scrollbar-prevents-click.html"
2. follow the instructions and try to click on the link at the bottom of the red box


Actual results:

when i try to click the Test-B link, the bottom scrollbar appears and hides the link, so it is not possible to click on it


Expected results:

1. the scrollbar should not prevent to click on an element
2. the scrollbar should only appear when i scroll

reproducible with Firefox 58, 59, 60.0a1 (2018-02-21) (64-bit)
works in: safari 11.0.3

Comment 1

[Ciprian Muresan [:cmuresan], Formerly of Ecosystem QA - please needinfo @mcoman for things regarding the team]

User Agent 	Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:60.0) Gecko/20100101 Firefox/60.0
Build ID 	20180226230123

I have managed to reproduce this issue on the latest Firefox release and the latest Nightly. It seems to have always behaved this way ever since the scroll bars were introduced in bug 636564.

If I set the scrollbars to always show from the Mac general settings, this issue is not reproducible.

Comment 2

[Stephen A Pohl [:spohl]]

I'm unable to reproduce this.
Does this depend on a particular version of macOS?
Does this reproduce with both trackpad and external mouse?
Does this depend on how big or small the browser window is?

Comment 3

[Ciprian Muresan [:cmuresan], Formerly of Ecosystem QA - please needinfo @mcoman for things regarding the team]

Attachment: recording for 1440237.mov

It looks like the issue is only reproducible on 10.13 if you don't let the scrollbar disappear first. 
It is reproducible on 10.11 with "Show scroll bars: When scrolling" option set.
It is reproducible on 10.12 with "Show scroll bars" set to either "Automatically" or "When scrolling"

It is reproducible with both trackpad and external mouse.

It does not depend on the browser window.

I've attached a screen recording from 10.12.

Comment 4

[Attila Soki]

Attachment: second-recording-for-1440237.mov

on my mac (macOS 10.13.3 (17D102)), the scrollbars are set to "automatically based on mouse or trackpad" and i can reproduce this always, not only if i don't let the scrollbar disappear.
see the screen recording "second-recording-for-1440237.mov"

the scrollbar seems to appear on click, first a thin one, then immediately a ticker one

Comment 5

[Liz Henry (:lizzard) (relman/hg->git project)]

Too late to fix for 58 or 59 but we can still take a patch for 60/61.