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Issue 866923 link

Starred by 2 users

Issue metadata

Status: Fixed
Owner:
Closed: Oct 24
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: Linux
Pri: 3
Type: Bug



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Scrollbar below a certain size doesn't have a cursor/handle

Reported by teo8...@gmail.com, Jul 24

Issue description

UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36

Example URL:
http://matteosistisette.com/test/stupidchrome/select-scrollbar/

Steps to reproduce the problem:
1. go to http://matteosistisette.com/test/stupidchrome/select-scrollbar/

What is the expected behavior?
The scrollbar of the multiple <select> item should have a... how is it called? a cursor? a handle? That rectangle that you can drag up and down to scroll.

A scrollbar should ALWAYS have that.

What went wrong?
There is no such thing. The scrollbar has no "handle", apparently "because" the scrollbar is too short. 

The serious flaw is not so much that you can't drag the handle to scroll: it would be difficult anyway, so using the arrow buttons is preferred. But what is unacceptable is that you have no indication whatsoever of where you are in the scrolling range.

If this was a design decision, it is ridiculous.

Does it occur on multiple sites: N/A

Is it a problem with a plugin? N/A 

Did this work before? N/A 

Does this work in other browsers? N/A

Chrome version: 67.0.3396.99  Channel: stable
OS Version: 
Flash Version:
 
Components: Blink>Scroll
Labels: Needs-Triage-M67
Cc: viswa.karala@chromium.org
Labels: Triaged-ET Target-70 M-70 FoundIn-70
Status: Untriaged (was: Unconfirmed)
Able to reproduce the issue on chrome reported version# 67.0.3396.99, latest stable# 68.0.3440.75 and on latest chrome# 70.0.3501.0 using Ubuntu 16.04 with URL provided in comment# 0. As this issue is seen from M-60(60.0.3112.0), hence considering this issue as Non-Regression and marking it as Untriaged.
Note: Issue is not seen on Windows-10 and Mac 10.12.6.

Thanks!
Labels: -Pri-2 -Type-Compat Hotlist-Polish Hotlist-GoodFirstBug Pri-3 Type-Bug
Owner: chaopeng@chromium.org
Status: Assigned (was: Untriaged)
Yup - this is a bug. Linux-only, the thumb is painted on Windows (though it doesn't move at all). It's a bit of a degenerate case so low-pri.
Cc: bokan@chromium.org
Can I take this issue if there is no one working on this?
Cc: khero...@gmail.com
Sure! I can't assign the bug to you since you're not a project member yet but we can leave it on chaopeng@ for now.

The bug only repros on a low-DPI screen (--force-device-scale-factor=1 if you have a high DPI screen). This says to me the issue is in the "uncomposited" path (i.e. Blink draws the scroller and scrollbars, rather than creating a composited layer for accelerated scrolling).

Some places to start looking:

The major class in Blink for scrollbars is in blink/renderer/core/scroll/scrollbar.cc. That encapsulates a scrollbar and its behavior.

For painting and platform behavior, we have a ScrollbarTheme class. This is implemented differently on each platform. In Linux it'll be the ScrollbarThemeAura class. A good place to start might be ScrollbarThemeAura::PaintThumb [1] and see if it's being called and what's happening there.

Finally, I doubt the bug is this deep, but the real "under the hood" painting code is in NativeThemeAura [2].

[1] https://cs.chromium.org/chromium/src/third_party/blink/renderer/core/scroll/scrollbar_theme_aura.cc?sq=package:chromium&g=0&l=286

[2] https://cs.chromium.org/chromium/src/ui/native_theme/native_theme_aura.cc?targetos=chromium&g=0&l=186


Project Member

Comment 8 by bugdroid1@chromium.org, Oct 24

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621

commit a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621
Author: HyeockJinKim <kherootz@gmail.com>
Date: Wed Oct 24 02:27:46 2018

Make scrollbar always have thumb

Bug:  866923 
Change-Id: I7e68f4b199ae41280e3745d47849fe3557d24661
Reviewed-on: https://chromium-review.googlesource.com/c/1257723
Commit-Queue: Jinho Bang <jinho.bang@samsung.com>
Reviewed-by: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602222}
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/WebKit/LayoutTests/platform/linux/fast/forms/select/listbox-appearance-basic-expected.png
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/WebKit/LayoutTests/platform/linux/fast/forms/select/menulist-appearance-basic-expected.png
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/WebKit/LayoutTests/platform/linux/fast/forms/textarea/basic-textareas-expected.png
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/WebKit/LayoutTests/platform/linux/fast/forms/textarea/basic-textareas-quirks-expected.png
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/WebKit/LayoutTests/platform/linux/scrollbars/border-box-rect-clips-scrollbars-expected.png
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/WebKit/LayoutTests/platform/linux/virtual/prefer_compositing_to_lcd_text/scrollbars/border-box-rect-clips-scrollbars-expected.png
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/WebKit/LayoutTests/platform/mac/scrollbars/overflow-scrollbar-combinations-expected.png
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/WebKit/LayoutTests/platform/win/fast/forms/select/listbox-appearance-basic-expected.png
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/WebKit/LayoutTests/platform/win/fast/forms/select/menulist-appearance-basic-expected.png
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/WebKit/LayoutTests/platform/win/fast/forms/textarea/basic-textareas-expected.png
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/WebKit/LayoutTests/platform/win/fast/forms/textarea/basic-textareas-quirks-expected.png
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/WebKit/LayoutTests/platform/win/scrollbars/border-box-rect-clips-scrollbars-expected.png
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/WebKit/LayoutTests/platform/win/virtual/prefer_compositing_to_lcd_text/scrollbars/border-box-rect-clips-scrollbars-expected.png
[modify] https://crrev.com/a9c34e0c8fd23a45ef35d4a811e4ae0dc92c0621/third_party/blink/renderer/core/scroll/scrollbar_theme.cc

Status: Fixed (was: Assigned)
This should be fixed by the patch in #8. Thanks kherootz@!
Project Member

Comment 10 by bugdroid1@chromium.org, Jan 8

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ab55e934d7269b282b513a75f00d9e7043c880c6

commit ab55e934d7269b282b513a75f00d9e7043c880c6
Author: Morten Stenshorne <mstensho@chromium.org>
Date: Tue Jan 08 15:04:46 2019

[LayoutNG] Rebaseline fast/forms/textarea/basic-textareas-quirks.html

Most other expectations seem to have been rebaselined as part of
https://chromium-review.googlesource.com/c/chromium/src/+/1257723
(but LayoutNG was left out).

TBR=kherootz@gmail.com,kojii@chromium.org

Bug:  866923 
Change-Id: I3d21fc960933ca6f242741b6fb0bffeb472b0e3b
Reviewed-on: https://chromium-review.googlesource.com/c/1400670
Reviewed-by: Morten Stenshorne <mstensho@chromium.org>
Commit-Queue: Morten Stenshorne <mstensho@chromium.org>
Cr-Commit-Position: refs/heads/master@{#620722}
[modify] https://crrev.com/ab55e934d7269b282b513a75f00d9e7043c880c6/third_party/blink/web_tests/FlagExpectations/enable-blink-features=LayoutNG
[modify] https://crrev.com/ab55e934d7269b282b513a75f00d9e7043c880c6/third_party/blink/web_tests/flag-specific/enable-blink-features=LayoutNG/fast/forms/textarea/basic-textareas-quirks-expected.png

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