It’s a little complicated to reproduce.
(in chinese locate)
- Prepare a long topic with many posts, for example 200 posts. And I don’t read it before, or read at very beginning position, e.g. first 10 posts.
- Enter the topic and scroll the scoller handle up. Then the scroller shows a button “Back”. Make sure the progress indicator is high enough, can inside the handle if scroller handle reaches top.
- Continue to scroll up, until the handle reach or very close to the start date.
And you will see the overlap.