I cannot reproduce on Mac M-59 Canary or Linux M-58 Beta.

We have a very minor painting bug on Mac where we clip the rounded scroll thumb when the scrollbar is very short, but the scrollbar does appear and disappear as expected.

The initial report says all versions <= 59, but the report meta data say it's M-56. Could you confirm exactly which versions you have tried?

What are your Mac OS scrollbar preferences? They sometimes affect when scrollbars paint/layout/etc.

Can you reduce the page at all?

Reproduced on Version 59.0.3047.0 (Official Build) dev (64-bit) in Ubuntu 16.10
Reproduced on Version 57.0.2987.98 Built on Ubuntu , running on Ubuntu 16.10 (64-bit)
Reproduced on Version 57.0.2987.133 (64-bit) on Mac

The order is very specific, if you load the page with a large height and shrink it down the scroll bar removes as expected when growing the page again.  Only if you load the page initially with a short height and then grow the page does the effect occur.

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

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

Thanks. Now I can reproduce on Linux (haven't looked on Mac).

Testers:
1. Open a new window and make it vertically small (about 100 pixels)
2. Load the page and clink on the "Menu". Note 2 sets of scrollbars, which is correct.
3. Resize the page vertically to about 700 pixels (not more, the smaller scroll bar should still be there) and note the larger scroll bar does not go away.

I suspect this comes out of scrolling work by bokan@, but it may also be some form of paint invalidation.

Oh yeah, that's weird - I'd guess maybe related to layout calls inside scrollbar change code? But those are generally affecting overlays more than layout scrollbars. I'll see if I can reduce this down. In the mean time, a bisect would be helpful.

schenney@, any reason it's a P1? Doesn't necessarily look like a regression or particularly bad.

I have found that if I sit on the page and go to a different x window (like a linux terminal and then go back to chrome as the active window then (infrequently) the scrollbar will be there for a second and disappear on its own.  I theorize that there is some internal triggers that can possibly make it repaint/recalculate and go away.  As for regression it would have had to occur prior to chromium 56 but I have not tested <= 55 so origin version is unknown to me.

Able to reproduce the issue on Windows-7(Desktop), Linux Ubuntu 14.04(Desktop) using chrome Stable version 57.0.2987.133 and canary 59.0.3066.0 with the steps mentioned in comment#5.
This is Non-regression issue, observed from M30 #30.0.1550.0 and marking it as Untriaged to get more inputs from dev team.
Note:Issue not observed on MacBook Air-10.12.4 and Ubuntu-14.04(Laptop).

Please find the attached screen cast for reference.

Thanks.

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Given this issue isn't a regressions I'm lowering priority to normal P3.

I don't believe the above video captures the bug here because in the old M30 the content browser has yet to implement media-queries and thus has actual scroll to do.  My first image more accurately represents and causes bug because even though the scrollbar is auto it still shows up even though there is no actual slider inside the bar.

Also with an undetermined date of fix I don't know if I wish to keep the bug in place or overflow: hidden; the element with some javascript.

```javascript
val navi = document.querySelector('.eapl-local-nav__drawer-body');
if(navi.getBoundingClientRect().height == navi.scrollHeight) { navi.style.overflowY: hidden; }
```

If someone has the time to reduce it down with the actual bug intact that would be appreciated so that I can put in my js hack to fix it.

Managed to distil the page down to a minimal repro:

1) Open the attached file
2) Resize the window smaller vertically until a scrollbar appears on the image.
3) Resize the window larger to where it shouldn't need a scrollbar

Expected:
Scrollbar disappears since the box is overflow: auto and didn't have a scrollbar on load.

Actual:
Scrollbar remains but is disabled

This looks like a layout issue with flexbox. Over to cbiesinger@ to triage.

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Ah, hold off for a bit, I just realised I lost the <DOCTYPE html> in the process and that seems to have an effect.

Ok, fixed minimal repro attached. This one's got the html DOCTYPE

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For the record, I agree with the priority reduction. It was not affecting site functionality.

I agree lower priority there is an easy javascript workaround and glad you could distill it down so that I didn't have to keep the issue up on site.