Added a border to the preview pane (#6114)

Author: yaira2

Files/UserControls/PreviewPane.xaml

@@ -25,16 +25,12 @@
         </ResourceDictionary>
     </UserControl.Resources>
 
-    <UserControl.Transitions>
-        <TransitionCollection>
-            <PaneThemeTransition x:Name="PreviewPaneTransition" Edge="{x:Bind EdgeTransitionLocation, Mode=OneWay}" />
-        </TransitionCollection>
-    </UserControl.Transitions>
-
     <Grid
         x:Name="RootGrid"
         HorizontalAlignment="Stretch"
-        Background="{ThemeResource PreviewPaneBackgroundBrush}">
+        Background="{ThemeResource PreviewPaneBackgroundBrush}"
+        BorderBrush="{ThemeResource ControlStrokeColorDefault}"
+        BorderThickness="0,0,0,1">
         <Grid.RowDefinitions>
             <RowDefinition Height="2*" MinHeight="100" />
             <RowDefinition

Files/UserControls/PreviewPane.xaml.cs

@@ -45,22 +45,9 @@ public bool IsHorizontal
             set
             {
                 SetValue(IsHorizontalProperty, value);
-                EdgeTransitionLocation = value ? EdgeTransitionLocation.Bottom : EdgeTransitionLocation.Right;
             }
         }
 
-        public static DependencyProperty EdgeTransitionLocationProperty =
-            DependencyProperty.Register("EdgeTransitionLocation",
-                                        typeof(EdgeTransitionLocation),
-                                        typeof(PreviewPane),
-                                        new PropertyMetadata(null));
-
-        private EdgeTransitionLocation EdgeTransitionLocation
-        {
-            get => (EdgeTransitionLocation)GetValue(EdgeTransitionLocationProperty);
-            set => SetValue(EdgeTransitionLocationProperty, value);
-        }
-
         private string GetLocalizedText(string resName) => resName.GetLocalized();
 
         private void UserControl_Unloaded(object sender, RoutedEventArgs e)