2056650 - Custom newtab wallpapers flash / blink some seconds after loading newtab

Status: VERIFIED FIXED

(Firefox :: New Tab Page, defect)

Description

[Mike Conley (:mconley) (:⚙️)]

Filing this on behalf of Stephen Field. He's in a situation where, after setting the background to a custom wallpaper from PoTD (this one: https://upload.wikimedia.org/wikipedia/commons/2/27/STS-135_Atlantis%27_final_tow_back.jpg), then after browser launch OR after opening a newtab, that background will flash some number of seconds after tab load. It's pretty distracting.

Comment 1

[Mike Conley (:mconley) (:⚙️)]

Notably, Stephen is not able to reproduce when using one of the built-in wallpapers. Only when it comes from PoTD does he see this flash.

Comment 2

[Mike Conley (:mconley) (:⚙️)]

Attachment: Flash when opening customize panel

This isn't exactly the same thing, but I notice that if I click on the customize panel after opening a new tab, the background flashes.

Comment 3

[Scott [:thecount] Downe]

Attachment: Bug 2056650 - Mark moz-newtab-wallpaper as known-cacheable so newtab custom wallpapers stop flashing

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/6b76f1879571
https://hg.mozilla.org/integration/autoland/rev/e43993ee433f
Mark moz-newtab-wallpaper as known-cacheable so newtab custom wallpapers stop flashing r=desktop-theme-reviewers,mconley,emilio

Comment 5

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/e43993ee433f

Comment 6

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/e43993ee433f

Comment 7

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/e43993ee433f

Comment 8

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/e43993ee433f

Comment 9

[Phabricator Automation]

firefox-beta Uplift Approval Request

• User impact if declined/Reason for urgency: Noticeable wallpaper flash for the user
• Code covered by automated testing?: yes
• Fix verified in Nightly?: no
• Needs manual QE testing?: yes
• Steps to reproduce for manual QE testing: Steps to test in the original phabricator
• Risk associated with taking this patch: low
• Explanation of risk level: It's a 1 line to extend an existing thing into an existing pattern
• String changes made/needed?: None
• Is Android affected?: no

Comment 10

[Scott [:thecount] Downe]

Attachment: Bug 2056650 - Mark moz-newtab-wallpaper as known-cacheable so newtab custom wallpapers stop flashing

Newtab has its own special wallpaper protocol for custom wallpapers, and it
was missing from the knownCacheable detection. Combined with newtab
preloading, that made the image periodically fail ValidateEntry and get
re-requested, causing the flash.

Original Revision: https://phabricator.services.mozilla.com/D313305

Comment 11

[Scott [:thecount] Downe]

Attachment: Bug 2056650 - Mark moz-newtab-wallpaper as known-cacheable so newtab custom wallpapers stop flashing

Newtab has its own special wallpaper protocol for custom wallpapers, and it
was missing from the knownCacheable detection. Combined with newtab
preloading, that made the image periodically fail ValidateEntry and get
re-requested, causing the flash.

Original Revision: https://phabricator.services.mozilla.com/D313305

Comment 12

[Phabricator Automation]

firefox-beta Uplift Approval Request

• User impact if declined/Reason for urgency: For the planned July 28 dot release.

I didn't know this would also request beta, so I already requested a beta uplift as well, sorry about that.

This fixes a noticible wallpaper flash

• Code covered by automated testing?: yes
• Fix verified in Nightly?: no
• Needs manual QE testing?: yes
• Steps to reproduce for manual QE testing: Steps to test in the original phabricator
• Risk associated with taking this patch: low
• Explanation of risk level: It's a 1 line change to use an existing pattern
• String changes made/needed?: None
• Is Android affected?: no

Comment 13

[Phabricator Automation]

firefox-release Uplift Approval Request

• User impact if declined/Reason for urgency: For the planned July 28 dot release.

I didn't know this would also request beta, so I already requested a beta uplift as well, sorry about that.

This fixes a noticible wallpaper flash

• Code covered by automated testing?: yes
• Fix verified in Nightly?: no
• Needs manual QE testing?: yes
• Steps to reproduce for manual QE testing: Steps to test in the original phabricator
• Risk associated with taking this patch: low
• Explanation of risk level: It's a 1 line change to use an existing pattern
• String changes made/needed?: None
• Is Android affected?: no

Comment 14

[Scott [:thecount] Downe]

Attachment: Bug 2056650 - Mark moz-newtab-wallpaper as known-cacheable so newtab custom wallpapers stop flashing

Newtab has its own special wallpaper protocol for custom wallpapers, and it
was missing from the knownCacheable detection. Combined with newtab
preloading, that made the image periodically fail ValidateEntry and get
re-requested, causing the flash.

Original Revision: https://phabricator.services.mozilla.com/D313305

Comment 15

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/89706b190d83
https://hg.mozilla.org/releases/mozilla-beta/rev/656c1cbe06f6

Comment 16

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/29658300527c
https://hg.mozilla.org/releases/mozilla-release/rev/7ee078e4e912

Comment 17

[Catalin Sasca, Desktop Test Engineering [:csasca]]

Verified that this is fixed on Firefox 153.0.1, Firefox 154.0b3 and Firefox 155.0a1 (2026-07-27). Tests were performed on macOS 26.5.2, Windows 11 and Ubuntu 26.04.

Comment 18

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-esr153/rev/f771d1aa37ad

Comment 19

[Catalin Sasca, Desktop Test Engineering [:csasca]]

Verified that this is fixed on Firefox ESR 153.1.0. Tests were performed on macOS 27, Windows 11 and Ubuntu 26.04.