1941523 - The New Tab page has a large horizontal scrollbar at certain screen sizes when sections are enabled

Status: VERIFIED FIXED

(Firefox :: New Tab Page, defect)

Description

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

Attachment: explorer_HY0CZqTw6i.mp4

[Affected versions]:

• Firefox Beta 135.0b3 - Build ID: 20250110123854
• Firefox Nightly 136.0a1 - Build ID: 20250113214519

[Affected Platforms]:

• Windows 10
• macOS 14
• Ubuntu 22.04

[Prerequisites]:

• Have the following prefs set in about:config in a new profile:
  • browser.newtabpage.activity-stream.discoverystream.sections.enabled to true
  • browser.newtabpage.activity-stream.discoverystream.sections.personalization.enabled to true
  • browser.search.region to US
• Use an en-US Firefox Build

[Steps to reproduce]:

1. Open the browser using the profile from prerequisites.
2. Open a New Tab.
3. Maximize the Firefox Window and observe the bottom part of the window.

[Expected result]:

• The page is only scroll-able vertically.

[Actual result]:

• The page has a a horizontal scrollbar and the page width is larger depending on the window size.

[Regression Window]:

• 22:34.90 INFO: Last good revision: e65e5888566ed72163ccbacecf3f78499d144ed5
• 22:34.90 INFO: First bad revision: 8205ad36ed89a6656aec466670fe24427a7e054d
• 22:34.90 INFO: Pushlog: https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=e65e5888566ed72163ccbacecf3f78499d144ed5&tochange=8205ad36ed89a6656aec466670fe24427a7e054d

[Notes]:

• Attached a screen recording of the issue.

@maxx, if looks like bug 1933150 caused this regression. Could you please take a look at this?

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1933150

Comment 2

[Maxx Crawford [:maxx]]

Checking with the team - it could also be the recent billboards work as well (adjusts the page width to allow for content)

Comment 3

[Nathan Barrett [:nbarrett]]

Attachment: Bug 1941523 - fix horizontal scroll with sections r=#home-newtab-reviewers

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/2e591adceaf1
fix horizontal scroll with sections r=home-newtab-reviewers,maxx

Comment 5

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/2e591adceaf1

Comment 6

[BugBot [:suhaib / :marco/ :calixte]]

The patch landed in nightly and beta is affected.
:nbarrett, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
• If no, please set status-firefox135 to wontfix.

For more information, please visit BugBot documentation.

Comment 7

[Nathan Barrett [:nbarrett]]

Attachment: Bug 1941523 - fix horizontal scroll with sections r=#home-newtab-reviewers

Original Revision: https://phabricator.services.mozilla.com/D234525

Comment 8

[Phabricator Automation]

beta Uplift Approval Request

• User impact if declined: horizontal scroll on newtab
• Code covered by automated testing: yes
• Fix verified in Nightly: no
• Needs manual QE test: yes
• Steps to reproduce for manual QE testing: enable prefs: browser.newtabpage.activity-stream.discoverystream.sections.cards.enabled and browser.newtabpage.activity-stream.discoverystream.sections.enabled a horizontal scroll bar should not be visible.
• Risk associated with taking this patch: low
• Explanation of risk level: CSS changes, only visual issues.
• String changes made/needed: no
• Is Android affected?: no

Comment 9

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-beta/rev/a0538d305eb5

Comment 10

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

I have verified that the issue is no longer reproducible on the latest Firefox Nightly 136.0a1 (Build ID 20250120214839) and Firefox Beta 135.0b7 (Build ID 20250120093501) using Windows 10, macOS 15.1, and Ubuntu 24.04.