[Affected versions]:

• Fx 90.0b

[Affected platforms]:

• Windows 10 x64
• macOS 10.15
• Ubuntu 16.04 LTS x86

[Steps to reproduce]:

1. Launch Firefox, access about:preferences.
2. Search for a term that can be found inside subdialogs or doorhangers (e.g. "Firefox").
3. Scroll down to HTTPS-Only Mode.

[Expected result]:

• The tooltips are placed above, at the middle of a button.

[Actual result]:

• There is a tooltip displayed, but there is no button present.

[Regression range]:

• This issue only reproduces on Fx 90.0b builds, I will return with a regression range.

[Additional notes]:

• Tried this on both a clean and used profile with the same result.
• The HTTPS-Only Mode is not displayed in nightly, however even after enabling that with dom.security.https_only_mode in about:config, the issue doesn't reproduce on any nightly (I have tried 89 and 90 nightly versions).
• The first occurrence was found on beta: 90.0b1.

Regression window:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=5d03a9d6cb8aeba1bb488b989712ad9cfa0546d2&tochange=8347db9863fc1c6dfe8d15fb4eb1426f283a6b53

I can reproduce the issue since the build landed Bug 1662710.
This is not a regression, but an implementation problem.

Thank you, Alice!

:ccomorasu, since this bug is a regression, could you fill (if possible) the regressed_by field?
For more information, please visit auto_nag documentation.

After further investigation I agree with comment 1. It is an implementation error. Updating the bug accordingly.

I'm also removing the align=end, because the vbox is adjacent to a flex=1 vbox,
so all horizontal space will be eaten by that other box, meaning alignment of
the button is a no-op as its container is the same width as the button anyway.

(In reply to Cristian Comorasu, QA [:ccomorasu], Release Desktop QA from comment #0)

2. Search for a term that can be found inside subdialogs or doorhangers (e.g. "Firefox").

• The HTTPS-Only Mode is not displayed in nightly, however even after enabling that with dom.security.https_only_mode in about:config, the issue doesn't reproduce on any nightly (I have tried 89 and 90 nightly versions).

This is because the brand name of nightly is "Nightly". Searching for "Nightly" allows reproducing the bug on nightly.

https://hg.mozilla.org/mozilla-central/rev/01351267a9dd

Reproduced the issue on Fx 90.0b1 Windows 10 x64.
Issue verified as fixed on Fx 91.0b9 and Fx 92.0a1 Windows 10 x64, Ubuntu 18.4 and macOS 10.12.6