Xorg session, Xubuntu 18.04

Able to reproduce this issue on reported version 68.0.3440.17, latest beta 68.0.3440.25 and latest canary 69.0.3461.2 using Windows 10 and Ubuntu 14.04. i.e; On clicking with mouse wheel on scrollbar doesn't scroll to clicked position.

This issue is seen from M-60. Hence considering this issue as Non-Regression and marking as Untriaged.

Thanks!

Thanks for the report. This was an intentional change made in https://crrev.com/11b79e0f80933879da85ea22a438a36b2a0cb2d6 to fix other bugs so this is now working as intended (and matches behavior in Firefox and other apps).

It's not wirking as intended. A middle mouse click is expected to scroll the bar to the place of the click in X server environment. GTK+ may also behave like this on a left click instead of middle mouse click.
Currently none of this works in Chromium, and it is not possible to scroll the page to the place of click in the scroll bar! It does work in Firefox, Chromium does not match it.

Windows does not have this feature of scrolling to the place of click, and Windows users and developers may be unaware about it.

What is 'matching other apps behaviour' is actually just a GTK+ setting: https://developer.gnome.org/gtk3/stable/GtkSettings.html#GtkSettings--gtk-primary-button-warps-slider

In firefox, when gtk-primary-button-warps-slider=1, left click scrolls to the place of the click, shift+left click just scrolls a bit, but not to the place of the click, and ctrl+left click scrolls to the place of the click.

With gtk-primary-button-warps-slider=0 in ~/.config/gtk-3.0/settings.ini , middle click on any place of the scrollbar in Firefox scrolls the page to the place of the click (as it was in Chromium before).

Sorry about that - I took a closer look and it does look like this was intentional behavior in Chrome (we don't respect the gtk setting and it's off on my system so I don't see it in other apps). Thanks for the description.

Chao, this patch broke a theme setting: WebScrollbarBehaviorImpl::ShouldCenterOnThumb called from Scrollbar::MouseDown so we do need to forward a middle click to the scrollbar. 

In this case, should we forward middle click to scrollbar but not allow drag?

I think in this case drag is expected. We should probably keep track of which mouse button caused the capture.

Yes, I know that Chromium does not use GTK's native scrollbars, just tried to explain that this change dod not make Chromium behave as other apps. Thanks.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/012f690ae71459a546feab0b580c3f793682a102

commit 012f690ae71459a546feab0b580c3f793682a102
Author: chaopeng <chaopeng@chromium.org>
Date: Wed Jul 04 17:43:41 2018

Do not pass the mouse press to scrollbar if scrollbar pressed.

If user left button down then move cursor out of scrollbar then middle
button down, we would not clear the last_scrollbar_under_mouse_.

Bug:  852943 
Change-Id: I1546fa201f0ab8cda77d8444f51b97966d3d68f8
Reviewed-on: https://chromium-review.googlesource.com/1114181
Commit-Queue: Jianpeng Chao <chaopeng@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572614}
[delete] https://crrev.com/e6da4f138ccefccc641cdc28eb60622df779a1fc/third_party/WebKit/LayoutTests/fast/scrolling/scrollbar-mousedown-move-mouseup-expected.txt
[modify] https://crrev.com/012f690ae71459a546feab0b580c3f793682a102/third_party/WebKit/LayoutTests/fast/scrolling/scrollbar-mousedown-move-mouseup.html
[modify] https://crrev.com/012f690ae71459a546feab0b580c3f793682a102/third_party/WebKit/LayoutTests/resources/gesture-util.js
[modify] https://crrev.com/012f690ae71459a546feab0b580c3f793682a102/third_party/blink/renderer/core/input/event_handler.cc
[modify] https://crrev.com/012f690ae71459a546feab0b580c3f793682a102/third_party/blink/renderer/core/layout/scrollbars_test.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6e94d9afe46647811f36d530fc283c40a7705cb2

commit 6e94d9afe46647811f36d530fc283c40a7705cb2
Author: Ella Ge <eirage@chromium.org>
Date: Wed Jul 04 20:47:57 2018

Revert "Do not pass the mouse press to scrollbar if scrollbar pressed."

This reverts commit 012f690ae71459a546feab0b580c3f793682a102.

Reason for revert: 
virtual/threaded/fast/scrolling/scrollbar-mousedown-move-mouseup.html
is failing on Linux and mac trybot.
See:
https://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=webkit_layout_tests&tests=virtual%2Fthreaded%2Ffast%2Fscrolling%2Fscrollbar-mousedown-move-mouseup.html


Original change's description:
> Do not pass the mouse press to scrollbar if scrollbar pressed.
> 
> If user left button down then move cursor out of scrollbar then middle
> button down, we would not clear the last_scrollbar_under_mouse_.
> 
> Bug:  852943 
> Change-Id: I1546fa201f0ab8cda77d8444f51b97966d3d68f8
> Reviewed-on: https://chromium-review.googlesource.com/1114181
> Commit-Queue: Jianpeng Chao <chaopeng@chromium.org>
> Reviewed-by: David Bokan <bokan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#572614}

TBR=bokan@chromium.org,chaopeng@chromium.org

Change-Id: I4067e4384e2ee2a2c0672b53813c800b7647108b
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug:  852943 
Reviewed-on: https://chromium-review.googlesource.com/1126499
Reviewed-by: Ella Ge <eirage@chromium.org>
Commit-Queue: Ella Ge <eirage@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572649}
[add] https://crrev.com/6e94d9afe46647811f36d530fc283c40a7705cb2/third_party/WebKit/LayoutTests/fast/scrolling/scrollbar-mousedown-move-mouseup-expected.txt
[modify] https://crrev.com/6e94d9afe46647811f36d530fc283c40a7705cb2/third_party/WebKit/LayoutTests/fast/scrolling/scrollbar-mousedown-move-mouseup.html
[modify] https://crrev.com/6e94d9afe46647811f36d530fc283c40a7705cb2/third_party/WebKit/LayoutTests/resources/gesture-util.js
[modify] https://crrev.com/6e94d9afe46647811f36d530fc283c40a7705cb2/third_party/blink/renderer/core/input/event_handler.cc
[modify] https://crrev.com/6e94d9afe46647811f36d530fc283c40a7705cb2/third_party/blink/renderer/core/layout/scrollbars_test.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2f19fc93c1551e4aef30c535e47a09ee326cd428

commit 2f19fc93c1551e4aef30c535e47a09ee326cd428
Author: chaopeng <chaopeng@chromium.org>
Date: Thu Jul 05 17:10:18 2018

Reland "Do not pass the mouse press to scrollbar if scrollbar pressed."

This is a reland of 012f690ae71459a546feab0b580c3f793682a102

Original change's description:
> Do not pass the mouse press to scrollbar if scrollbar pressed.
>
> If user left button down then move cursor out of scrollbar then middle
> button down, we would not clear the last_scrollbar_under_mouse_.
>
> Bug:  852943 
> Change-Id: I1546fa201f0ab8cda77d8444f51b97966d3d68f8
> Reviewed-on: https://chromium-review.googlesource.com/1114181
> Commit-Queue: Jianpeng Chao <chaopeng@chromium.org>
> Reviewed-by: David Bokan <bokan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#572614}

TBR=bokan@chromium.org

Bug:  852943 
Change-Id: I2117f386b6d9f197eb23bfb980517a91ba0db294
Reviewed-on: https://chromium-review.googlesource.com/1127219
Commit-Queue: Jianpeng Chao <chaopeng@chromium.org>
Reviewed-by: Jianpeng Chao <chaopeng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572818}
[delete] https://crrev.com/c99685a9319190025271a1b7a3f8aabd52d6ff2d/third_party/WebKit/LayoutTests/fast/scrolling/scrollbar-mousedown-move-mouseup-expected.txt
[modify] https://crrev.com/2f19fc93c1551e4aef30c535e47a09ee326cd428/third_party/WebKit/LayoutTests/fast/scrolling/scrollbar-mousedown-move-mouseup.html
[modify] https://crrev.com/2f19fc93c1551e4aef30c535e47a09ee326cd428/third_party/WebKit/LayoutTests/resources/gesture-util.js
[modify] https://crrev.com/2f19fc93c1551e4aef30c535e47a09ee326cd428/third_party/blink/renderer/core/input/event_handler.cc
[modify] https://crrev.com/2f19fc93c1551e4aef30c535e47a09ee326cd428/third_party/blink/renderer/core/layout/scrollbars_test.cc

 Issue 867640  has been merged into this issue.

I'm finding this to be quite painful. The fix in #15 appears to be low-risk. Can it be merged to M68?

This bug requires manual review: Request affecting a post-stable build
Please contact the milestone owner if you have questions.
Owners: cmasso@(Android), kariahda@(iOS), bhthompson@(ChromeOS), abdulsyed@(Desktop)

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

I would also be happy to see it backported to 68.

How safe is this merge? What are the chances of it introducing new regressions?

I think this is low-risk.

Note, it's still possible to make the scrollbar warp-to-cursor in the affected Chrome versions by using shift-left-click in place of middle-click.

Approvng merge to M68. Branch:3440

Hi awpritchard, Please give me some reproduce step. Also please test on latest canary. Thank you.

I mean that shift-left-click is still working as intended, and can be used in place of middle-click as a workaround for this bug report.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b948a57bacd5306827064563d0b673e9fd304d64

commit b948a57bacd5306827064563d0b673e9fd304d64
Author: chaopeng <chaopeng@chromium.org>
Date: Fri Jul 27 22:27:56 2018

Reland "Do not pass the mouse press to scrollbar if scrollbar pressed."

This is a reland of 012f690ae71459a546feab0b580c3f793682a102

Original change's description:
> Do not pass the mouse press to scrollbar if scrollbar pressed.
>
> If user left button down then move cursor out of scrollbar then middle
> button down, we would not clear the last_scrollbar_under_mouse_.
>
> Bug:  852943 
> Change-Id: I1546fa201f0ab8cda77d8444f51b97966d3d68f8
> Reviewed-on: https://chromium-review.googlesource.com/1114181
> Commit-Queue: Jianpeng Chao <chaopeng@chromium.org>
> Reviewed-by: David Bokan <bokan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#572614}

TBR=bokan@chromium.org, chaopeng@chromium.org

(cherry picked from commit 2f19fc93c1551e4aef30c535e47a09ee326cd428)

Bug:  852943 
Change-Id: I2117f386b6d9f197eb23bfb980517a91ba0db294
Reviewed-on: https://chromium-review.googlesource.com/1127219
Commit-Queue: Jianpeng Chao <chaopeng@chromium.org>
Reviewed-by: Jianpeng Chao <chaopeng@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#572818}
Reviewed-on: https://chromium-review.googlesource.com/1153836
Cr-Commit-Position: refs/branch-heads/3440@{#765}
Cr-Branched-From: 010ddcfda246975d194964ccf20038ebbdec6084-refs/heads/master@{#561733}
[delete] https://crrev.com/c954124e2b7ef87a475c6da8d815c5a4315f306f/third_party/WebKit/LayoutTests/fast/scrolling/scrollbar-mousedown-move-mouseup-expected.txt
[modify] https://crrev.com/b948a57bacd5306827064563d0b673e9fd304d64/third_party/WebKit/LayoutTests/fast/scrolling/scrollbar-mousedown-move-mouseup.html
[modify] https://crrev.com/b948a57bacd5306827064563d0b673e9fd304d64/third_party/WebKit/LayoutTests/resources/gesture-util.js
[modify] https://crrev.com/b948a57bacd5306827064563d0b673e9fd304d64/third_party/blink/renderer/core/input/event_handler.cc
[modify] https://crrev.com/b948a57bacd5306827064563d0b673e9fd304d64/third_party/blink/renderer/core/layout/scrollbars_test.cc