Steps to Reproduce

1. run attached zul, visit with Chrome under Window 10
2. drag the scroll thumb with a mouse and move down slowly
3. move to item 20 and stop, keep pressing the mouse without releasing

Current Result

the scroll thumb keep moving down until I release the mouse button
autoMoving.mp4

Expected Result

scroll thumb doesn't move when a mouse stops

Debug Information

• 8.5.0.1 doesn't have this bug

Happen on

• Chrome 87, window 10
• Edge, window 10

Do Not happen

• firefox 83, windows 10
• Chrome 87, Mac 10.14

Workaround

• use the mouse wheel
• release the mouse button
• .z-tree-body { overflow-anchor: none; }

  according to https://bugs.chromium.org/p/chromium/issues/detail?id=685785