2052711 - Sidebars like bookmarks no longer remain visible or appear when toggled in fullscreen mode (F11)

Status: VERIFIED FIXED

(Firefox :: Sidebar, defect)

Description

[Kestrel]

Attachment: Bookmarks sidebar auto-hides in fullscreen mode

STR:

1. Launch latest Nightly 154.0a1.
2. Open the bookmarks sidebar (Ctrl+B).
3. Enter fullscreen mode (F11).
4. Toggle the bookmarks sidebar (Ctrl+B) several times.

Expected:
Bookmarks sidebar remains visible in fullscreen mode like before and appears when toggled.

Actual:
Bookmarks sidebar auto-hides along with toolbar and does not appear when toggled.

In the process of making the vertical tabs sidebar auto-hide in fullscreen mode (Bug 1927457), now all sidebars auto-hide. None of the Bug 1927457 duplicates requested this and many users will likely prefer the previous behavior of sidebars remaining visible and optional.

The vertical tabs sidebar only needs to auto-hide when sidebars are closed. This would be equivalent to the way it worked with horizontal tabs.

Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=35caa667047b5a4df400247beda7b0ab2dcbc6c3&tochange=923ce0510c229edc85fa6963a138b98084c4ca61

Regressed by Bug 1927457.

Comment 1

[BugBot [:suhaib / :marco]]

:Sylvestre, since you are the author of the regressor, bug 1927457, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 2

[Sylvestre Ledru [:Sylvestre]]

Attachment: Bug 2052711 - Keep panel sidebars visible in F11 fullscreen r?#tabbrowser-reviewers,sclements,emilio

Bug 1927457 collapsed all sidebar elements on fullscreenNavToolboxHidden, so in
F11 the panel sidebars (bookmarks, history) hid too and Ctrl+B couldn't bring
them back. The intent was to hide only the tools/vertical-tabs launcher, like
the horizontal tab strip.

Split the CSS: the launcher (#sidebar-container, #sidebar-launcher-splitter)
still hides with the toolbox, while the panel (#sidebar-box, #sidebar-splitter)
only hides in DOM fullscreen and stays toggleable in F11.

Comment 3

[Sam Foster [:sfoster] (he/him)]

(In reply to Kestrel from comment #0)

Expected:
Bookmarks sidebar remains visible in fullscreen mode like before and appears when toggled.

I'm not sure this is the behavior we want, even if its technically a regression. Was this always the behavior of sidebars in f11 fullscreen? What is the use case - full-screen is normally interpreted to mean content fullscreen, and the sidebars are usually thought of as chrome.

Comment 6

[Merci chao]

(In reply to Sam Foster [:sfoster] (he/him) from comment #3)

I'm not sure this is the behavior we want, even if its technically a regression. Was this always the behavior of sidebars in f11 fullscreen? What is the use case - full-screen is normally interpreted to mean content fullscreen, and the sidebars are usually thought of as chrome.

I agree that the sidebar should hide in full screen, but it should also remain accessible when the user wants. In the case of bug #2055389, I simply cannot access the vertical tabs, which should still be available when using horizontal tabs. Perhaps the sidebar could appear when pointing the cursor at the edge, similar to how the toolbox works.

Comment 7

[наб]

"Was this always the behavior of sidebars in f11 fullscreen?" No, you used to be able to use the history. And you were able to see and use the history when you opened it up with ^H.
"What's the use-case" In both cases: the history feature is very useful in a browser.
"full-screen is normally interpreted to mean content fullscreen" That's ahistorical. Decades of tradition show that full-screen is normally interpreted as "go fullscreen, kill most internal decorations, and if you press ^H or ^F (or ${shortcut}) or mouse over the top of the window (or take other actions to call up browser boxes) they show up so you can use them while browsing, &c. &c."

Comment 8

[Sam Foster [:sfoster] (he/him)]

Ok I think we are all in agreement here: f11 should initially fullscreen the content. But hovering the top or side edges should show whatever toolbars/sidebars were previously visible.

I'll take a note of the keyboard shortcut expectation - that seems reasonable. In fullscreen, ctrl+B, ctrl+H etc should slide in the appropriate toolbar.

Comment 9

[Sam Foster [:sfoster] (he/him)]

We have a new UX spec for maximised windows and fullscreen (which agrees with comment 8). Rather than trying to kind-of implement some pieces of it as we fix this regression, I think this bug should focus on just putting things back to how they were before bug 1927457 and we'll scope and prioritize implementing the new spec separately.

Comment 10

[BugBot [:suhaib / :marco]]

Set release status flags based on info from the regressing bug 1927457

Comment 11

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/f0efa59a7415
https://hg.mozilla.org/integration/autoland/rev/2f36029f863e
Keep panel sidebars visible in F11 fullscreen r=emilio,desktop-theme-reviewers,dao,sfoster

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/958f658f7212
https://hg.mozilla.org/integration/autoland/rev/9bbbd60f9aeb
Revert "Bug 2052711 - Keep panel sidebars visible in F11 fullscreen r=emilio,desktop-theme-reviewers,dao,sfoster" for causgin bc failures at browser_panelUINotifications_fullscreen.js

Comment 13

[rperta]

Backed out for causgin bc failures at browser_panelUINotifications_fullscreen.js
Backout link
Push with failures
Failure log(s)

Comment 14

[Pulsebot]

Pushed by [e-mail]:
https://github.com/mozilla-firefox/firefox/commit/9c716f78b062
https://hg.mozilla.org/integration/autoland/rev/89b4b6a6d542
Keep panel sidebars visible in F11 fullscreen r=emilio,desktop-theme-reviewers,dao,sfoster

Comment 15

[amarc]

https://hg.mozilla.org/mozilla-central/rev/89b4b6a6d542

Comment 16

[BugBot [:suhaib / :marco]]

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

• If yes, please nominate the patch for beta approval.
  • See https://wiki.mozilla.org/Release_Management/Requesting_an_Uplift for documentation on how to request an uplift.
• If no, please set status-firefox154 to wontfix.

For more information, please visit BugBot documentation.

Comment 17

[Sylvestre Ledru [:Sylvestre]]

Attachment: Bug 2052711 - Keep panel sidebars visible in F11 fullscreen

Bug 1927457 collapsed all sidebar elements on fullscreenNavToolboxHidden, so in
F11 the panel sidebars (bookmarks, history) hid too and Ctrl+B couldn't bring
them back. The intent was to hide only the tools/vertical-tabs launcher, like
the horizontal tab strip.

Split the CSS: the launcher (#sidebar-container, #sidebar-launcher-splitter)
still hides with the toolbox, while the panel (#sidebar-box, #sidebar-splitter)
only hides in DOM fullscreen and stays toggleable in F11.

Original Revision: https://phabricator.services.mozilla.com/D310515

Comment 18

[Phabricator Automation]

firefox-beta Uplift Approval Request

• User impact if declined/Reason for urgency: important regression with f11 + vertical tabs
• Code covered by automated testing?: yes
• Fix verified in Nightly?: yes
• Needs manual QE testing?: yes
• Steps to reproduce for manual QE testing: 1) open fx

2. enable vertical tabs
3. open a few tabs
4. move to full screen
5. tests that you can change tabs, open bookmark or not, etc

• Risk associated with taking this patch: medium
• Explanation of risk level: it is very user visible
• String changes made/needed?: nope
• Is Android affected?: no

Comment 19

[Sylvestre Ledru [:Sylvestre]]

yeah, i just did!

Comment 20

[Pulsebot]

https://github.com/mozilla-firefox/firefox/commit/044a50e49932
https://hg.mozilla.org/releases/mozilla-beta/rev/b728a7606819

Comment 21

[Negritas Sergiu, Desktop QA]

Hello! I can confirm that the issue is fixed with firefox 154.0b4 and 155.0a1(2026-07-29) on Ubuntu 24.04 and macOS 15.7.7

I will update the status and flags of this issue.

Have a nice day!