1994663 - tab group label width expanded when dragged

Status: NEW

(Firefox :: Tabbed Browser, defect, P2)

Description

[Steve]

Attachment: demo.mkv

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:144.0) Gecko/20100101 Firefox/144.0

Steps to reproduce:

When tab group is dragged, it unexpectedly expands into the full width of the sidebar.

This is only happening when expand on hover is enabled. And it appears to be a new issue on FF 144.0, not observed on previous versions.

Actual results:

Tab group label width expanded.

Expected results:

Tab group label stays at text width.

Comment 1

[Steve]

Attachment: demo.mp4

mkv isn't playing, try converted to mp4

Comment 2

[Steve]

Maybe related to this issue? https://bugzilla.mozilla.org/show_bug.cgi?id=1988437

Comment 3

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

The Bugbug bot thinks this bug should belong to the 'Firefox::Tabbed Browser' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 4

[Ardelean Oana, Desktop Test Engineering [:oardelean]]

Hello, thank you for the bug report!
Managed to reproduce this issue on:

• Firefox 145.0b8;
• Firefox 144.0.2;

Tested and reproduced on:

• Windows 10;
• macOS 15;
• Ubuntu 22;

Could not reproduce on Firefox Nightly 146.0a1.

Setting as NEW so the developing team can have a look.

Comment 5

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

The severity field is not set for this bug.
:mak, could you have a look please?

For more information, please visit BugBot documentation.

Comment 6

[Buddy J.]

To be honest, as a user I think the tab group labels look better when they take up the whole width when using vertical tabs. Perhaps this could be turned into a feature?

Comment 7

[Steve]

This is still happening on Firefox 146.0 (X11; Linux x86_64)

Comment 8

[Steve]

This was fixed in the previous couple versions, but seems to regressed in Firefox 149.

Comment 9

[Dan]

Adding a user perspective here: the full-width label behavior is actually significantly better for usability in vertical tabs. When the pill stretches to the full sidebar width, it creates a clear visual separator between tab groups, making it much easier to scan and navigate between groups at a glance.

Would it be possible to expose this as a hidden preference (e.g. browser.tabs.groups.label.fullWidth) even if the default remains text-width?
This would let users who prefer the full-width behavior opt in without changing the default for everyone.

Comment 10

[Steve]

This is still happening on FF 150 & 151.