Affected versions

• Fx 88.0b6
• Fx 89.0a1

Affected platforms

• Ubuntu 20.04 x64

Steps to reproduce

1. Launch Firefox
2. Bookmark a website, then click on the star button from the URL to edit this bookmark.
3. Click on "Show all the bookmarks folders" from location section.
4. Click Remove Bookmark.
5. Click again on star button.

Expected result

• The "Add Bookmark" dropdown appear under the star button, in the correct position.

Actual result

• The "Add Bookmark" dropdown is moving to the left, see the attached screencast.
  Starting from this step, the bookmark dropdown appear in wrong position.

Regression range

• Not a recent regression I reproduced on Fx 81.0b6. I will come back with the regression range ASAP.

Additional notes

• The steps may need to be repeated to reproduced this issue.

I've investigated this issue on Ubuntu 20.04 x64, in order to find a regression range, and it seems that the bug reproduces all the way back to 55.0a1. This issue is not a regression, clicking on "Show all bookmarks folder" then dismiss this dialog box, after this click the bookmark star a second time the "New Bookmark" or the "Edit This Bookmark" dialog box shift to left. So it looks like following the previous steps, this functionality has always been broken.