We've tried to reproduce this issue, but everything seems to work as expected at our side.
I've prepared a sample project using our Telerik UI for WPF version 2015.3.1104 and a VirtualizingStackPanel
for a RadListBox
You can find the project attached as well as a video showing how it behaves at our side.
Could you please take a look and let us know if we are missing something?
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items