With the world settings screen open, clicking on approximately the bottom 1/3 of the scroll bar on the right edge has no effect; the click is ignored. It doesn't matter whether what you're clicking on contains the "thumb", or is below it.

Steps to reproduce:

1. Open the world settings for any world in a Windows 10 PC.
2. If your window is so large that the entire settings is visible, reduce the window size to make the scroll bar appear.
3. Right-click the mouse in the bottom 1/3 of the scroll bar.

Expected results:
If you clicked below the "thumb", the window scrolls downward and the thumb moves to the position you clicked. If you clicked on the thumb and held the mouse button down, you can drag the thumb up and down to scroll the window.

Actual results:
Nothing happens; your click is ignored.