#1,006 – Scrollbars in a ListBox Appear as Needed

Scrolling in a ListBox is managed by a ScrollViewer, which contains the items panel of the ListBox.  The ScrollViewer provides scrolling logic and makes available both a horizontal and a vertical scrollbar.

The visibility of the scrollbars in a ScrollViewer is controlled by the HorizontalScrollBarVisibility and VerticalScrollBarVisibility properties.  By default, both of these properties are set to Auto for the ScrollViewer used in a ListBox.  This means that the scrollbar only appears if the content of the ListBox does not fit in the associated dimension.