1851367 - Tab list blinking on mouse hover if many tabs are opened

Status: UNCONFIRMED

(Firefox :: Tabbed Browser, defect, P5)

Description

[haswellready]

User Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:109.0) Gecko/20100101 Firefox/115.0

Steps to reproduce:

I hover mouse pointer to a tab.

• Open a lot of tabs so that each of them become as narrow as possible.
• Set option "Show close button on each tab" (maybe it's not related)
• Pin 10-15 tabs (maybe it's not related)

Actual results:

No blinkning

Expected results:

Blinking

Comment 1

[haswellready]

https://i.imgur.com/enDjgaq.gif

The age of this bug is not less than 3-5 years.

Comment 2

[haswellready]

It maybe also help to reproduce th bug:

• Add button "New tab" at the left corner of the main window (not sure if its related).
• Add button "List of all tabs" (not sure if it's related)

https://i.imgur.com/cqXmiYT.png
https://i.imgur.com/HthXikz.png

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

[Dão Gottwald [:dao]]

Do you have any userChrome.css modifications, or have you modified the browser.tabs.tabMinWidth pref?

Note for the future, we may want to make sure tab contents can't overflow the tab by setting overflow:hidden, or we may want to increase the minimum tabMinWidth, or both.

Comment 5

[Daniel Bodea [:danibodea]]

I have attempted reproduction in Firefox ESR v115.0.3esr on Windows 10, but I could not reproduce the reported behavior.
Notes:

• loaded about 100 tabs
• pinned about 15 of them
• set to show the "X" button even if the tab is smaller:
  • set browser.tabs.tabClipWidth = 50 (this is not a supported change so the UI might break because of it)
  • set browser.tabs.tabMinWidth = 50 (this is not a supported change so the UI might break because of it)
• moved the "New Tab" button to the left side
• "List of all tabs" button is at the right of the open tabs by default.

The only reproduction I can reproduce is that the tab's "Close" button would flicker and spill out of the tab when hovered, but this UI breaking is quite expected considering that the tab's min-width and clip-width preferences have been changed to 50px.

What the reporter experiences is something a little different: on top of the reproduction I succeded in reproducing (the spill-out of the "X" button in the tab, the "tabs scroll to right" button appears and disappears on hover (demo in comment 1).

WARNING: Changing preferences through the about:config interface is not officially supported.
Hidden settings edited using the about:config tool are explicitly not supported, which means that Mozilla makes no guarantees they will be supported in the future, or that Mozilla will fix them if they break. Mozilla does not test these preferences, and will not in the future. That includes security and performance testing which these preferences may affect.

Can you try reverting the change of the browser.tabs.tabClipWidth and browser.tabs.tabMinWidth to their default values and let us know if it still reproduces?

Thank you for your contribution!

Comment 6

[haswellready]

browser.tabs.tabMinWidth = 25 (non default)
browser.tabs.tabClipWidth = 140 (default)

What if I like narrow tabs? I know many people do.

Comment 7

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

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

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