1714890 - 89.0 64-bit - flickering and unusable tab

Status: RESOLVED INCOMPLETE

(Firefox :: Tabbed Browser, defect)

Description

[bugzilldg]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:89.0) Gecko/20100101 Firefox/89.0

Steps to reproduce:

In Firefox 89, 64-bit on my Windows 10 computer, when the tabs reach a certain amount (for my screen resolution and FF tab width and spacing, it happens to be 23 open tabs), the rightmost (23rd for me) tab will fast-flicker when it's moused over. No action can be taken with the tab.

Actual results:

As described above, the tab will fast-flicker. One can't enter the contents of the tab. One can't close the tab. The workaround is to open another tab, and then at that point, the problematic tab, the newly-added tab - everything - start working normally again. The only problem is when the "magic number" tab (again, for my settings, 23) is opened, with that one tab, until tabs to its left are closed, or tabs to its right opened.

Expected results:

Normal tab behavior allowing full access to the tab and its contents and its options.

Comment 1

[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 revert this change in case you think the bot is wrong.

Comment 2

[Clara Guerrero ( Need Info Brindusa Tot Please)]

Hi,

I am not able to replicate the issue on my end (attaching screenshots). I've tried on: windows 10 pro
On the following versions:
release 89.0 (64-bit)
Installed both beta 90.0b4 and nightly 91.0a1 (2021-06-07) (64-bit)
I've tried having different amount of tabs and I see no flickering issue, and I'm able to access the content for the last tab on the right. Can you share a video demonstarting the issue please?

Please, also attach your about:support

Thanks for the report.
Best regards, Clara.

Comment 3

[Clara Guerrero ( Need Info Brindusa Tot Please)]

Attachment: tabs.JPG

Comment 4

[Clara Guerrero ( Need Info Brindusa Tot Please)]

Attachment: tabs2.JPG

Comment 5

[Clara Guerrero ( Need Info Brindusa Tot Please)]

Attachment: ff 89.0 (64-bit).JPG

Comment 6

[bugzilldg]

Attachment: about_support.txt

Comment 7

[bugzilldg]

(In reply to Clara Guerrero from comment #2)

Hi,

I am not able to replicate the issue on my end (attaching screenshots). I've tried on: windows 10 pro
On the following versions:
release 89.0 (64-bit)
Installed both beta 90.0b4 and nightly 91.0a1 (2021-06-07) (64-bit)
I've tried having different amount of tabs and I see no flickering issue, and I'm able to access the content for the last tab on the right. Can you share a video demonstarting the issue please?

Please, also attach your about:support

Thanks for the report.
Best regards, Clara.

I can't attach a video (user ignorance, sorry).

But it's pretty simple to replicate for me by repeating the following sequence until mousing over the rightmost tab generates rapid flicker:

• Open new tab
• Mouse over it

On my work laptop, 1920 pixel display, the 27th and 28th tabs trigger this - <=26 is fine, as is >= 29. To make clear, one can put in 2500 tabs and the rightmost one will be fine. The only issue is with the one or two tabs that "trigger" the limit - 23rd on my 1280 pixel monitor, 27th on my 1920 pixel laptop. Adding one or two more tabs, and the flicker goes away. So start with 15-20 tabs, and systematically add one at a time as above, until the problem occurs.

My about:support is attached.

Comment 8

[bugzilldg]

(In reply to Clara Guerrero from comment #2)

Hi,

I am not able to replicate the issue on my end (attaching screenshots). I've tried on: windows 10 pro
On the following versions:
release 89.0 (64-bit)
Installed both beta 90.0b4 and nightly 91.0a1 (2021-06-07) (64-bit)
I've tried having different amount of tabs and I see no flickering issue, and I'm able to access the content for the last tab on the right. Can you share a video demonstarting the issue please?

Please, also attach your about:support

Thanks for the report.
Best regards, Clara.

Here's another material fact. I have a separate portable FF I just installed to test another bug. It has none of my profile from this main Firefox. Because of that, the tabs are pretty wide on it, and just scroll off the screen once I get to - I don't know, 10 tabs? In my configured Firefox, I have narrowed the tab width, so I can fit many more on a screen without scrolling off. This almost certainly contributes to the tab flicker I describe.

Comment 9

[Clara Guerrero ( Need Info Brindusa Tot Please)]

Thanks for the feedback, could you please answer the following questions in order to further investigate this issue?

1- Does this issue happen with a new profile? Here is a link on how to create a new profile: https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles
2- Are you using add-ons? If so could you please list them? (you can try the issue while in Safe Mode. You can find helpful info here : https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode .)
3- Does this issue occur in the latest nightly version of firefox? Here is a link from where you can download it: https://www.mozilla.org/en-US/firefox/channel/desktop/
Best,

Clara

Comment 10

[:Gijs (he/him)]

This sounds pretty bad, but unfortunately without more details that allow us to reproduce / narrow down the cause, it is difficult for us to do anything about it. We can reopen the report if more details become available.