Affected versions

• 88.0a1(2021-03-24), 87.0, 88.0b1;

Affected platforms

• Windows 10, macOS 10.15;

Steps to reproduce

1. Launch Firefox, access the Customize page;
2. Drag buttons in the Overflow menu (drag the Firefox Account and Text Encoding for reference);
3. In the overflow menu click on the Firefox Account and drag it to another position;
4. In the overflow menu click on the Text Encoding and drag it to another position;

Expected result

• icon animates on mouse click;

Actual result

• Firefox Account lacks the icon animation;

Regression range

• not a regression, visible with addition of button on 2019-03-18/2019-03-18;
• Pushlog: URL
• Potential regressor:

Additional notes

• reproducible with proton prefs on/off;
• attached recording to best illustrate the issue.