Moving folders · Data Parking (the two-pane mover)
Why does the other pane scroll when I hover over an item in Data Parking?
Short answer: That's mirror-hover: while the panes are paired, hovering over or selecting an item on one side scrolls the other side to the matching item, so you can compare both copies at a glance.
That's mirror-hover. When the panes are paired, hovering over or selecting an item on one side scrolls the other side to the matching item, so you can see both copies of a file at once without losing your place. It only happens while the panes are paired.