When you select an item in Design or Code view, you want the Structure panel to scroll to the item you have selected.
When you are selecting and deleting things from within the Structure panel itself, you need the contents to stay still, otherwise once you delete something the panel moves away from where you are working and have your focus.
This is a feature request to stop the panel from auto-scrolling in this situation, or at least to give an option for this.
Here is a video to show the issue, taken in Beta 7 v6: