[DropDownList] The skip variable is not updated correctly in a virtualisation scenario

[PekoPPT]

Describe the bug A clear and concise description of what the bug is.

To Reproduce

1. Open this project
2. Use the scrollbar and scroll to Item 600
3. Using a mouse start scrolling fast in an upside direction.
4. Some items are missing on the top of the list of items

Expected behavior There shouldn't be missing items at the top of the list of items

Screenshots Video: https://www.dailymotion.com/video/k5P0hMi2v5r54nzidJI