It would be great to have ScrollPositionIndicatorTemplate for RadListBox, similar to RadGridView (see RadGridView's implementation here http://docs.telerik.com/devtools/wpf/controls/radgridview/features/scrolling).

Introduce a feature where a scroll position indicator is displayed when the deferred scrolling is enabled (ScrollViewer.IsDeferredScrollingEnabled=True). The scroll indicator is a small tooltip displayed next to the scrollbar and displaying information about the potential item that should be displayed at the top of the viewport. 

This is the same as in RadGridView's ScrollPositionIndicator. You can check this in the following help article: (http://docs.telerik.com/devtools/wpf/controls/radgridview/features/scrolling#scrollpositionindicator). See also the attached video.