Nightly 89.0a1 (2021-03-25) (64-Bit)
macOS 11.2.3

0.) Enable Proton-Tabs-Bar
1.) Open a New Tab
2.) Visit a page with a long title e.g. https://www.heise.de/news/Open-Source-made-in-Europe-befluegelt-Smart-Cities-weltweit-5991112.html?utm_source=pocket-newtab-global-de-DE
3.) Hover over the tab

Actual: Tab flickers next to the close button.

Expected: No flicker.

A screencast is attached.

This was expected and accepted behavior from the change in bug 1695140. It was the best I could come up with to allow more text to display but also allow the full area of the close button to become accessible once the mouse moved into the tab.

Set release status flags based on info from the regressing bug 1695140

Hi, this visual flicker disturbs me really everyday when hovering over tabs :( Any chance to fix this regression? Many thanks in advance :)

It's a P2, so at this point it's unlikely to be fixed for Firefox 89, but we might accept a patch. On the other hand, looking at comment 1, I think we should probably resolve this WONTFIX instead, since it was an intentional trade-off and is a very subtle effect that only occurs at the very end of a single tab…

Romain, what do you think?

WONTFIX would mean that we would not accept a patch, which is usually a pretty high bar.

Even if we don't know of a better solution to the tradeoff right now, it's possible we'll think of one in the future. So I'd be a bit concerned if we just closed this off entirely, since it's absolutely a polish issue and a reasonably-noticeable visual papercut. (It's been bothering me during proton dogfooding as well. Though I'm trying to ignore it. :) )

(In reply to Blake Winton (:bwinton) (:☕️) from comment #5)

is a very subtle effect that only occurs at the very end of a single tab…

To be clear, this affects every tab in the tabstrip, if the tab-title is long enough. I suppose you could say it only affects a single tab at a time (since it's triggered by hover, and you can only hover one tab-title at a time); but it does affect every tab, if you hover it.

I'm only seeing it on the tab with the close button, which is only one tab in both my DevEdition and my Nightly browsers, but perhaps that's because I have a bunch of tabs?

Yeah - if you have fewer tabs, then every tab has a close button.

Yes, the flicker appears on every tab with a close button, but it is not so much noticeable on the background tabs like on the focussed tab. A screencast is attached.

I totally understand that as much as text should be visible on a tab. But for a price to live with a visual and annoying flicker should not be the end of the solution.

Please don't Wontfix this report. Please be so kind and find a fix for the flicker. Many thanks.

This bug has been added to the Quality Foundations team's backlog. Ania (our Firefox desktop PM) is currently exploring a potential fix here.

(In reply to :prathiksha from comment #10)

This bug has been added to the Quality Foundations team's backlog. Ania (our Firefox desktop PM) is currently exploring a potential fix here.

Thanks !