Affected versions

• 66.0 build 3(20190314174725) - Acer distribution
• 66.0 build 2(20190225143501) - Acer distribution

Affected platforms

• Windows 8.1, Windows 10

Steps to reproduce
0. Install/Extract an older version of Firefox (ex. 58 )

1. Paste the acer_distribution folder inside the Firefox installed/extracted folder;
2. Launch Firefox;
3. Click on the Hamburger menu > Help > About Firefox;
4. After the updates are downloaded Click on the Restart to update button.

Expected result

• The About Firefox window - content is properly displayed;

Actual result

• There is a white line at the bottom of the window;
  (footer section not clamped to the bottom, probably pushed by the extra acer_build text)

Regression range

• does not seem to be a regression;

Additional notes

• detailed installed information can be found here
  *updating from 67.0a1 (2019-02-01) to 67.0a1 (2019-03-14) (32-bit) does not cause this issue to appear;

Another issue observed would be that the window was prepared to resize for any kind of text. While this is a really niche thing and probably users would have to do it on purpose, I'd still link it to this one.

Modifying this or any other string causes the window to expand and not truncate the text if needed.

This belongs in whatever frontend component owns this bit of UI... Gijs, perhaps you know where this should be classified?

This is a distribution issue and should be tracked there.

How important is this for 66? Can we aim to fix it in 67/68 or is this something you'd like to aim at a future dot release in 66?

As this is just a visual bug that is not a regression, I don't see it needed for a dot release.

https://hg.mozilla.org/mozilla-central/rev/3665b343720d

Issue has been indirectly verified durring the 68.0 Acer preload testing; it was no longer encountered so updating the status of the bug.