Affected versions

• 85.0a1 (2020-12-09)
• 84.0

Affected platforms

• Windows 10
• macOS 10.15
• Ubuntu 18.04

Steps to reproduce

1. Go to about:addons page
2. Reduce considerable the browser width
3. Click the Tools for all add-ons gear from the right-side in order to open its context menu

Expected result

• The context menu options are accessible

Actual result

• The context menu is cut off and some of the options can’t be accessed

Regression range

• Last good revision: 518df4329a20f76b3bffd5f6201b007fdebc274f (2019-11-01)
• First bad revision: 16aac90f6572f363d2b5c8205e13115ac818869d (2019-11-02)
• Pushlog:
  https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=518df4329a20f76b3bffd5f6201b007fdebc274f&tochange=16aac90f6572f363d2b5c8205e13115ac818869d

Suggested severity

• S4

This is when the browser has a small height, correct? The only way I can get the panel to go above the button is with a reduced browser height.

This is somewhat expected to me, but certainly not ideal. The code will position the panel in its alternate position if it can't fit in its preferred placement. It might make sense to pick whichever placement has more space if the preferred placement won't fit, but that won't entirely fix the bug. The panel would need to set a max-height to keep itself on screen and allow scrolling to fully fix this.