Release 150 tab split view functionality by rebloor · Pull Request #43589 · mdn/content

rebloor · 2026-03-26T18:17:33Z

Description

This PR addresses the dev-docs-needed requirements of:

Bug 2022549 tabs.move() taking a list of tabs should unsplit a split view when its tabs are explicitly listed apart
Bug 2016751 tabs.move() does not move a tab to the specified index when the destination is part of a split view

In addition, it adds a section summarizing the features for working with groups and split views in the working with the tab API article.

github-actions · 2026-03-26T18:19:03Z

Preview URLs (10 pages)

External URLs (4)

URL: /en-US/docs/Mozilla/Add-ons/WebExtensions/Working_with_the_Tabs_API
Title: Work with the Tabs API

https://github.com/w3c/webextensions/issues/967 (1 time) (Note! This may be a new URL 👀)
https://support.mozilla.org/en-US/kb/split-view-firefox (1 time) (Note! This may be a new URL 👀)

URL: /en-US/docs/Mozilla/Firefox/Releases/150
Title: Firefox 150 release notes for developers (Beta)

https://bugzil.la/2016762 (1 time) (Note! This may be a new URL 👀)
https://bugzil.la/2022549 (1 time) (Note! This may be a new URL 👀)

(comment last updated: 2026-03-30 17:20:53)

Rob--W · 2026-03-26T18:26:00Z

    });
    ```

+## Working with tab groups and split views


Tab groups and split views are distinct features. Please list them separately.

Done and links updated

Rob--W · 2026-03-26T18:26:57Z

+> Features to work with a tab group are provided in {{WebExtAPIRef("tabGroups")}}.
+
+> [!NOTE]
+> APIs to enable the creation and removal of split views (without moving or removing the tabs) are being developed under ([Firefox bug 2016928](https://bugzil.la/2016928)).


Let's use w3c/webextensions#967 as a reference instead. This is a cross-browser API design effort.

Rob--W · 2026-03-26T18:27:44Z

 ## Changes for add-on developers

+- The behavior of {{WebExtAPIRef("tabs.move")}} is updated for split views so that:
+  - The order of tabs in a split view can be swapped.


Please include bug numbers for reference, since we usually do so.

How did I miss those! Added

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com> Co-authored-by: Rob Wu <[email protected]>

Rob--W · 2026-03-27T00:27:07Z

 You can only move tabs to and from windows whose {{WebExtAPIRef('windows.WindowType', 'WindowType')}} is `"normal"`.

-When the call moves a tab or tabs in a split view, Firefox moves the tabs in the split view together to preserve the split view. In Chrome, moving a tab away from the other tab in a split view removes the split view.
+In Chrome, moving a tab away from the other tab in a split view removes the split view. This behavior may change in a future release.


Let's move this to a note below so that we introduce the split view behavior and only after that clarify that Chrome's behavior differs. I image that when the implementation changes that we want to document the standard behavior first and then have a note about older versions.

Rob--W · 2026-03-27T00:44:03Z


+## Working with tab groups
+
+Tab functionality enables users to create [group tabs](https://support.mozilla.org/en-US/kb/tab-groups).


I asked for a "split views" article because we don't have a better place to offer an overview of its capability and describe it.

For tab groups, the tabGroups API reference serves that purpose, and is linked from various places such as https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs/Tab#groupid

Can we use that as the canonical place for the description of what tab groups are instead of linking to SUMO here (that SUMO article is already linked from tabGroups MDN page).

Rob--W · 2026-03-27T00:56:48Z

+
+Tab functionality lets display two tabs side-by-side in a [split view](https://support.mozilla.org/en-US/kb/split-view-firefox).
+
+Various tab methods enable you to work with the content of groups and split views, including:


Please add text offering the following overview of relevant details. I am asking for this so we have one place where a dev can learn at once what they should do if they want to work with split views:

split view consists of exactly two adjacent tabs

when an individual tab of a split is moved, the other tab in the split moves with it to preserve the split (the emphasis here is to show that conceptually the pair of tabs in a split view should be regarded as one unit). The moved tab that moves along can be observed with tabs.onMoved.

when a tab is removed, the other tab in the split remains but is no longer part of a split view

given a tab, whether it is a member of a split view can be seen through its splitViewId property (https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs/Tab#splitviewid ). Split view membership changes can be observed through tabs.onUpdated

Co-authored-by: Rob Wu <[email protected]>

- removing working with tab groups from working with the tabs API article and adding additional details to the tabGroups API overview. - adding additional details to the working with split tabs in the working with the tabs API article - adding links to the working with split tabs section in the working with the tabs ID article - rewording the information about moving a tab in a split view

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

rebloor · 2026-03-30T17:15:08Z

@Rob--W your comment should all be addressed

Rob--W

Excellent update, thanks!

Release 150 tab split view functionality

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rebloor requested a review from Rob--W March 26, 2026 18:17

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Cross-link to the user guide on split view #43576

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		## Working with tab groups

		Tab functionality enables users to create [group tabs](https://support.mozilla.org/en-US/kb/tab-groups).


		Tab functionality lets display two tabs side-by-side in a [split view](https://support.mozilla.org/en-US/kb/split-view-firefox).

		Various tab methods enable you to work with the content of groups and split views, including:

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rebloor commented Mar 26, 2026

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github-actions Bot commented Mar 26, 2026 •

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