Affected versions

• 85.0a1 (2020-12-09), 84.0;

Affected platforms

• Windows 10, Ubuntu 20, macOS 10.15;

Steps to reproduce

1. Launch Firefox, access about:addons
2. Click on either Extensions or Plugins section;
3. Grab the browser, resize until the cogwheel is glued to the right-margin of the browser;
4. Click on the Cogwheel from right-side;

Expected result

• there would be 2 parts here:

• cogwheel to not touch the right-limit of the browser;
• menu to be pushed to left a few more pixels so opened menu and or focus ring to not appear cut;

Actual result

• focus ring + menu appear as cut on certain browser width(s);

Regression range

• not a regression, looking at older builds the button placement was not causing this issue to occur; with the redesign to the current layout it became visible;

Additional notes

• most visible on macOS where focus rings are bigger/blue;
• attached recording to best illustrate the issue;
• S4 as suggested severity, no real impact really edge-case scenario;
• same for the in-page Search menu-focus