ScrollViewerExtensions not respected for ListViews

[gplumb]

When using the AdonisUI.Extensions on a ListView, the scrollbars are always collapsed (and expand on hover), regardless of what are values actually set.

For example:

<ListView Name="lvUsers" SelectionChanged="lvUsers_SelectionChanged"
                      adonisExtensions:ScrollViewerExtension.HideScrollBarsUntilMouseOver="False"
                      adonisExtensions:ScrollViewerExtension.HorizontalScrollBarExpansionMode="AlwaysExpand"
                      adonisExtensions:ScrollViewerExtension.VerticalScrollBarExpansionMode="AlwaysExpand"
                      >
   <ListView.View>
      <GridView>
         ...
      </GridView>
   </ListView.View>
</ListView>

Expected behavior: The listview presents a "normal" scrollbar that's themed without any additional AdonisUI collapse behaviour

Actual: