Select scrollbar visibility in VirtualizationTest.

Does not currently work.

samples/VirtualizationTest/MainWindow.xaml

@@ -21,6 +21,12 @@
             <TextBox Watermark="Viewport"
                      UseFloatingWatermark="True"
                      Text="{Binding #listBox.Scroll.Viewport, Mode=OneWay}"/>
+            <TextBlock>Horiz. ScrollBar</TextBlock>
+            <DropDown Items="{Binding ScrollBarVisibilities}"
+                      SelectedItem="{Binding HorizontalScrollBarVisibility}"/>
+            <TextBlock>Vert. ScrollBar</TextBlock>
+            <DropDown Items="{Binding ScrollBarVisibilities}"
+                      SelectedItem="{Binding VerticalScrollBarVisibility}"/>
             <TextBox Watermark="Item to Create"
                      UseFloatingWatermark="True"
                      Text="{Binding NewItemString}"/>
@@ -35,7 +41,9 @@
                  Items="{Binding Items}" 
                  SelectedItems="{Binding SelectedItems}"
                  SelectionMode="Multiple"
-                 VirtualizationMode="{Binding VirtualizationMode}">
+                 VirtualizationMode="{Binding VirtualizationMode}"
+                 ScrollViewer.HorizontalScrollBarVisibility="{Binding HorizontalScrollBarVisibility, Mode=TwoWay}"
+                 ScrollViewer.VerticalScrollBarVisibility="{Binding VerticalScrollBarVisibility, Mode=TwoWay}">
             <ListBox.ItemsPanel>
                 <ItemsPanelTemplate>
                     <VirtualizingStackPanel Orientation="{Binding Orientation}"/>

samples/VirtualizationTest/ViewModels/MainWindowViewModel.cs

@@ -6,6 +6,7 @@ using System.Collections.Generic;
 using System.Linq;
 using Avalonia.Collections;
 using Avalonia.Controls;
+using Avalonia.Controls.Primitives;
 using ReactiveUI;
 
 namespace VirtualizationTest.ViewModels
@@ -17,6 +18,8 @@ namespace VirtualizationTest.ViewModels
         private int _newItemIndex;
         private IReactiveList<ItemViewModel> _items;
         private string _prefix = "Item";
+        private ScrollBarVisibility _horizontalScrollBarVisibility;
+        private ScrollBarVisibility _verticalScrollBarVisibility;
         private Orientation _orientation = Orientation.Vertical;
         private ItemVirtualizationMode _virtualizationMode = ItemVirtualizationMode.Simple;
 
@@ -64,6 +67,21 @@ namespace VirtualizationTest.ViewModels
         public IEnumerable<Orientation> Orientations =>
             Enum.GetValues(typeof(Orientation)).Cast<Orientation>();
 
+        public ScrollBarVisibility HorizontalScrollBarVisibility
+        {
+            get { return _horizontalScrollBarVisibility; }
+            set { this.RaiseAndSetIfChanged(ref _horizontalScrollBarVisibility, value); }
+        }
+
+        public ScrollBarVisibility VerticalScrollBarVisibility
+        {
+            get { return _verticalScrollBarVisibility; }
+            set { this.RaiseAndSetIfChanged(ref _verticalScrollBarVisibility, value); }
+        }
+
+        public IEnumerable<ScrollBarVisibility> ScrollBarVisibilities =>
+            Enum.GetValues(typeof(ScrollBarVisibility)).Cast<ScrollBarVisibility>();
+
         public ItemVirtualizationMode VirtualizationMode
         {
             get { return _virtualizationMode; }