Unable to reproduce the issue on reported chrome version 64.0.3282.119 and on the latest canary 66.0.3336.0 using Mac 10.13.1 with the below mentioned steps.
1. Launched Chrome
2. Navigated to https://en.wikipedia.org/wiki/Google_Chrome
3. Tried hovering the mouse pointer on scroll bar
4. Moved pointer out of that area
5. Retried to scroll again
We are able to see the scroll bar without being struck.

@Reporter: Could you please share a sample test URL/file where you are facing the issue. Any further inputs from your end may help us to triage the issue in a better way.

Thanks!

I was able to reproduce on that same URL (https://en.wikipedia.org/wiki/Google_Chrome). The key point of the example is to mouse over the scrollbar in the very small interval while the scrollbar is fading out of view, and while the scrollbar track is visible.

If the mouse enters the scrollbar track area in that brief period of time, and then you later initiate a scroll, then you should see the scroll indicator stuck in the 'expanded' state on the next scroll attempt.

For what it's worth, the issue appears to be purely cosmetic -- the scroller still functions perfectly fine; it just merely shown in the 'expanded' state when it should be in the smaller 'unexpanded' state. (Not sure if there's a better term to describe this)

Thank you for providing more feedback. Adding requester "vamshi.kommuri@techmahindra.com" to the cc list and removing "Needs-Feedback" label.

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kevinushey@ Thanks for the issue.

Tested this issue on Mac OS 10.13.3 on the reported version 64.0.3282.119, latest canary 66.0.3342.0 and Stable 64.0.3282.140 and unable to reproduce the issue by following the below steps.

1. Set the scroll bar settings in System Preferences -> General -> Show scroll bars -> Automatically based on mouse or trackpad.
2. Launched Chrome and navigated to a page which has vertical scroll bar.
3. On scrolling through the page, cannot see the scroll bar stuck and no issues are observed.
Attached is the screen cast for reference.

Request you to check and confirm if anything is missed from our end in testing the issue.

Also request you to provide the screen cast of the issue which will help in better understanding of the issue.

Thanks..

Deleted: 808151.webm 5.0 MB

	808151.webm 5.0 MB View Download

Thank you for providing more feedback. Adding requester "vamshi.kommuri@techmahindra.com" to the cc list and removing "Needs-Feedback" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Hi,

I attached a .mov file showcasing the issue in my initial post. The essential step you're missing in your attempt to reproduce the example is as I said:

   1. Begin scrolling a field, so a vertical scrollbar is shown.
   2. Mouse over the scrollbar, so that the scroll track is shown and the scrollbar is 'expanded'.
   3. Move the mouse outside of the scrollbar.
   4. In the brief time that the scrollbar is fading from view, try to mouse over the scrollbar again.
   5. Attempt to scroll once more.

Step 4) is crucial -- you must attempt to mouse over the scrollbar area _while the scrollbar is fading from view_. The window of time wherein this is possible is quite small, but it can happen (and might happen unintentionally while the user is scrolling).

Deleted: scrollbar.mov 221 KB

	scrollbar.mov 221 KB View Download

I think I see very similar behavior in Safari. Reporter can you confirm that is the case. I believe this is an OS level thing.

I'm not able to reproduce this specific issue in Safari (tested with Safari 11.0.3 on macOS 10.13.3).

It's worth noting that the behavior around how scrollbars are shown differs a bit between Safari and Chromium. In Chromium, the scrollbar expands as soon as the mouse enters the track area; in Safari, the scrollbar only expands if the user explicitly begins scrolling the page while the mouse cursor is within the track area. (Although it seems like this behavior is sometimes inconsistent, and can depend on whether the window has focus or not). Either way, I suspect this implies that there is some Chromium-specific code that leads to this behavior.

I wasn't able to reproduce a case where the scroll indicator was stuck as 'expanded' on Safari, although I did see a number of other minor issues. It seems inconsistent in Safari as to whether the scrollbar track is shown when the window is scrolled, especially if the scrolled window doesn't have focus.

Thank you for providing more feedback. Adding requester "dtapuska@chromium.org" to the cc list and removing "Needs-Feedback" label.

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Yeah, mac scrollbars in Chrome have some known bugs here. This is potentially related to issue 587877 but it looks like a slightly different way to repro the issue so I'll leave them separate.