Nightly 111.0a1 (2023-01-26) (64-Bit)
macOS 12.6.3

1.) Enable browser.urlbar.resultMenu
2.) Type something into the Address Bar, so that some history results appear
3.) Shrink the window until one of the results title starts to shrink/fade out
4.) Hover over that item

Actual: The item is pushed to the left when the Result Menu Button appears, which causes a kind of flicker.

Expected: The item should not pushed to the left. Result Menu Button should appear as an overlay without to push the item further to the left.

A demo is attached.

Thanks for checking.