1982214 - Tab widths expand when dragging and dropping a tab (Tab Bar overflowing)

Status: RESOLVED FIXED

(Firefox :: Tabbed Browser, defect)

Description

[moriyama164]

Attachment: Screencast showing steps and actual results on the overflowing Tab Bar in Nightly

Steps to reproduce:

1. Open multiple new tabs with Ctrl+T until the Tab Bar overflows.
2. Click the tab in the center of the Tab Bar.
3. Click the current tab's close button.
4. Repeat step 3 until the current tab becomes the rightmost tab.
5. Drag the current tab and drop it onto a location on a toolbar where it will not be detached (e.g., the Tab Bar or the Bookmarks Toolbar).

Note: From step 3 onward, make sure the cursor remains on the toolbars.

Actual results:
All tabs expand in width.

Expected results:
Tab widths should remain unchanged.

Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=5c69b37cb23d3c2e12709ef82bc022979dd7e9f9&tochange=78d86e496600cf1fb39b9c22b7c4c462a2dbbee8

Comment 1

[moriyama164]

This reports the same observable symptom as Bug 1982215, but the regression window differs.

Comment 2

[moriyama164]

Attachment: Screencast showing steps and expected results on the overflowing Tab Bar in Firefox 142.0b6

Comment 3

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

:sthompson, since you are the author of the regressor, bug 1972897, could you take a look?

For more information, please visit BugBot documentation.

Comment 4

[Stephen Thompson [:sthompson]]

I think this was fixed with bug 1982933, which is available in Firefox 142.0.1 and later. I get the expected results with Nightly 144.0a1 (2025-08-28). I'm going to close this as fixed, but please feel free to reopen if you still see this in a version that should have the fix for bug 1982933.