Add scroll bar to indicate how much is off screen

Add "Click to view more or reply" message.
Scroll to most recent comments.

Author: jcansdale

src/GitHub.InlineReviews/Views/CommentTooltipView.xaml

@@ -25,11 +25,19 @@
         </x:Array>
     </d:DesignProperties.DataContext>
 
-    <ItemsControl ItemsSource="{Binding Comments}">
-        <ItemsControl.ItemTemplate>
-            <DataTemplate>
-                <local:CommentView Margin="0 4"/>
-            </DataTemplate>
-        </ItemsControl.ItemTemplate>
-    </ItemsControl>
+    <DockPanel>
+        <StackPanel DockPanel.Dock="Bottom">
+            <Border BorderBrush="Silver" BorderThickness="0,1,0,0" Margin="0,8" />
+            <TextBlock x:Name="StatusTextBlock" FontStyle="Italic">Click to reply</TextBlock>
+        </StackPanel>
+        <ScrollViewer x:Name="CommentScrollViewer" VerticalScrollBarVisibility="Auto">
+            <ItemsControl ItemsSource="{Binding Comments}">
+                <ItemsControl.ItemTemplate>
+                    <DataTemplate>
+                        <local:CommentView Margin="0 4"/>
+                    </DataTemplate>
+                </ItemsControl.ItemTemplate>
+            </ItemsControl>
+        </ScrollViewer>
+    </DockPanel>
 </UserControl>

src/GitHub.InlineReviews/Views/CommentTooltipView.xaml.cs

@@ -1,4 +1,5 @@
 using System;
+using System.ComponentModel;
 using System.Windows.Controls;
 
 namespace GitHub.InlineReviews.Views
@@ -8,6 +9,18 @@ public partial class CommentTooltipView : UserControl
         public CommentTooltipView()
         {
             InitializeComponent();
+
+            CommentScrollViewer.LayoutUpdated += WatchForScrollBarVisible;
+        }
+
+        void WatchForScrollBarVisible(object sender, EventArgs e)
+        {
+            if (CommentScrollViewer.ComputedVerticalScrollBarVisibility == System.Windows.Visibility.Visible)
+            {
+                CommentScrollViewer.ScrollToBottom();
+                StatusTextBlock.Text = "Click to view more or reply";
+                CommentScrollViewer.LayoutUpdated -= WatchForScrollBarVisible;
+            }
         }
     }
 }