1703803 - Some tab titles pushed down a line oddly by system font with bogus metrics

Status: NEW

(Firefox :: Tabbed Browser, defect)

Description

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

Attachment: Vertical wrap bug with tab title

Nightly 89.0a1 (2021-04-07)
macOS 10.15.7

With the recent theme changes in Nightly on macOS, there seems to be a regression for certain tab titles (e.g. the page at https://elementary.io/, whose title tag currently contains "The fast, open, and privacy-respecting replacement for Windows and macOS ⋅ elementary OS") which pushes them down to the next line oddly.

STR:

1. Go to https://elementary.io/

ER:

The tab title should be vertically centred like the favicon.

AR:

The tab title is pushed down, as if it's wrapping oddly.

Comment 1

[Francesco Lodolo [:flod]]

Does it happen on a clean profile? It doesn't happen for me, on two different profiles and Nightly builds

Comment 2

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

(In reply to Francesco Lodolo [:flod] from comment #1)

Does it happen on a clean profile? It doesn't happen for me, on two different profiles and Nightly builds

Yes, for me it happens on a clean profile as well as my default profile.

Comment 3

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

Attachment: Address bar results

Results in the address bar are somehow also affected, if that helps to understand the root cause of the issue.

Comment 4

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

These issues seem to apply many / all pages on *.elementary.io domains, but other sites are working normally... 🤔

Comment 5

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

I've looked at this a bit more again today... It appears to be specifically caused by the character "⋅" in the site's title "The fast, open, and privacy-respecting replacement for Windows and macOS ⋅ elementary OS".

If I use the Browser Toolbox to manually edit just that one character out of the tab title, then it looks as expected.

I wonder if this caused by the font metrics for that character in whatever font is being used for the tab title...?

Comment 6

[J. Ryan Stinnett [:jryans] (Use needinfo, replies may be slow)]

Aha, indeed, it seems the character "⋅" does not exist in the ".SF NS" system font used for all the other characters, so Firefox was loading up some random "STIX Math" font I seem to have installed, and that gave the bogus metrics for that character.

I have worked around the issue by disabling this font I probably do not need anyway, but given that this issue did not occur with the previous tab design, there might be some value in locking down what fonts are used / disabling font fallback in the tab titles, so wacky fonts cannot distort the UI...?