Steps to reproduce:
1. Open the URL.
2. Use the down arrow key to scroll down to the middle of the page. As you scroll down, the comment filtering widget will detach and stick to the top left of the page.
3. In the comment filtering widget, drag the lower, dark gray handle one notch down.
As the handle moves down its edges on either side are not erased from their old position. See screenshot.
Created attachment 18890 [details]
Screenshot showing the bug
Created attachment 18892 [details]
Not reproducible in TOT.