1892394 - Moving the cursor on the next tab right before the tab preview is displayed will show the preview on the wrong tab

Status: VERIFIED FIXED

(Firefox :: Tabbed Browser, defect, P1)

Description

[Alexandru Trif, Desktop QA [:atrif]]

Attachment: tab_hover_0.gif

Found in

• 126.0b2

Affected versions

• 127.0a1 (2024-04-18)
• 126.0b2

Tested platforms

• Affected platforms: Ubuntu 23.10, Windows 10x64
• Unaffected platforms: macOS 14

Steps to reproduce

1. Open a few tabs.
2. Hover over a random tab and move the cursor to the next tab before the tab preview is displayed.

Expected result

• The tab preview is displayed for the correct tab.

Actual result

• The tab preview is displayed on the wrong tab.

Regression range

• Mozregression points at bug 1890397.

Additional notes

• Attached a screen recording.

Comment 1

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

:emilio, since you are the author of the regressor, bug 1890397, could you take a look?

For more information, please visit BugBot documentation.

Comment 2

[Emilio Cobos Álvarez (:emilio)]

I cannot reproduce this on Linux or Windows at all... Does it happen in the latest nightly?

Comment 3

[Alexandru Trif, Desktop QA [:atrif]]

Attachment: tab_hover_1.gif

(In reply to Emilio Cobos Álvarez (:emilio) from comment #2)

I cannot reproduce this on Linux or Windows at all... Does it happen in the latest nightly?

Yes, I can, but the issue is tricky to reproduce. I think the previous or next tab needs to be hovered when or right before the tab preview is displayed, so it requires perfect timing. If we hover the other tab too fast or too late the issue will not reproduce. Also, the tabs need to be loaded for the issue to persist. I have attached a screen recording. If more information is needed please let me know.

Comment 4

[Itiel]

I can reproduce something very similar to this (or maybe the same) when you overflow the tabbar and then scroll it.

Comment 5

[Greg Stoll :gstoll]

I'm not sure if this is the same issue or not, but I'm on Windows and when I have a bunch of tabs open, move my mouse to the tab bar, and spin my mouse wheel up quickly to scroll to the left, I can briefly see a tab preview showing far to the right of my Firefox window. (it took me a while to figure out what was going on; I would just see something flash on my other monitor out of the corner of my eye, which is very disconcerting!)

Comment 6

[Chris Peterson [:cpeterson]]

This bug is a THP release blocker.

Comment 7

[Jeremy Swinarton]

Attachment: Bug 1892394: Tab hover preview always displays on the correct tab r?dwalker!

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/8c1a33c7f442
Tab hover preview always displays on the correct tab r=dwalker,tabbrowser-reviewers,mak

Comment 9

[Sandor Molnar[:smolnar]]

https://hg.mozilla.org/mozilla-central/rev/8c1a33c7f442

Comment 10

[Giorgia Nichita, Release Desktop QA]

Verified as fixed using the latest Nightly 128.0a1 (2024-05-30) across the following platforms: Windows 11, Ubuntu 22 and macOS 13.