message: Fix styling of inactive selection on treeview in dark theme
diff: <!-- Brush for the selected item -->
  <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="{DynamicResource MahApps.Colors.Gray9}"/>
  + <SolidColorBrush x:Key="{x:Static SystemColors.InactiveSelectionHighlightBrushKey}" Color="{DynamicResource MahApps.Colors.Gray9}" />
  </TreeView.Resources>
  <i:Interaction.Triggers>
  <i:EventTrigger EventName="SelectedItemChanged">
  <!-- mouseover -->
  <SolidColorBrush x:Key="MahApps.Brushes.Accent3" Color="#99C9C9C9" />
  - <!-- Need to override this to firce it to work with our color prefs -->
  + <!-- Need to override this to force it to work with our color prefs -->
  <SolidColorBrush x:Key="MahApps.Brushes.Selected.Foreground" Color="{DynamicResource MahApps.Colors.ThemeForeground}" />
  </ListView.Resources>
  <ListView.ItemTemplate>
  