Describe the bug
The items inside the popup of the Multiselect are not correctly visualized when scrolling the data. The issue can be easily observed in scenarios where the page size and the total of records are close numbers.

The issue is that while scrolling, the Multiselect scrolls but the actual contents of the popup don't move until the scroll bar is more than halfway down.

To Reproduce

1. Open this project
2. Start scrolling the items in the MultiSelect

Expected behavior
With the move of the popup scroller down, the data should be scrolled too, no matter if the scroller has reached its middle position or not.

Screenshots
The screenshot is from the linked above example. The items displayed in the popup window should be around "Item 50"