From bfb334ca5ebfb249e5daebc878adbd3ea7fb4c3d Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Sat, 23 Jan 2016 20:48:03 +0100
Subject: [PATCH] Ensure TreeViewItem.IsSelected is set.

When TreeView.SelectedItem changes.
---
 src/Perspex.Controls/TreeView.cs              | 23 +++++++++++++++--
 .../TreeViewTests.cs                          | 25 +++++++++++++++++++
 2 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/src/Perspex.Controls/TreeView.cs b/src/Perspex.Controls/TreeView.cs
index 4b7b1f986a..0a83891bc8 100644
--- a/src/Perspex.Controls/TreeView.cs
+++ b/src/Perspex.Controls/TreeView.cs
@@ -46,8 +46,27 @@ namespace Perspex.Controls
         /// </summary>
         public object SelectedItem
         {
-            get { return _selectedItem; }
-            set { SetAndRaise(SelectedItemProperty, ref _selectedItem, value); }
+            get
+            {
+                return _selectedItem;
+            }
+
+            set
+            {
+                if (_selectedItem != null)
+                {
+                    var container = ItemContainerGenerator.Index.ContainerFromItem(_selectedItem);
+                    MarkContainerSelected(container, false);
+                }
+
+                SetAndRaise(SelectedItemProperty, ref _selectedItem, value);
+
+                if (_selectedItem != null)
+                {
+                    var container = ItemContainerGenerator.Index.ContainerFromItem(_selectedItem);
+                    MarkContainerSelected(container, true);
+                }
+            }
         }
 
         /// <inheritdoc/>
diff --git a/tests/Perspex.Controls.UnitTests/TreeViewTests.cs b/tests/Perspex.Controls.UnitTests/TreeViewTests.cs
index 8ee0d73a1e..f28cabe0f3 100644
--- a/tests/Perspex.Controls.UnitTests/TreeViewTests.cs
+++ b/tests/Perspex.Controls.UnitTests/TreeViewTests.cs
@@ -107,6 +107,31 @@ namespace Perspex.Controls.UnitTests
             Assert.True(container.IsSelected);
         }
 
+        [Fact]
+        public void Setting_SelectedItem_Should_Set_Container_Selected()
+        {
+            var tree = CreateTestTreeData();
+            var target = new TreeView
+            {
+                Template = CreateTreeViewTemplate(),
+                Items = tree,
+                DataTemplates = CreateNodeDataTemplate(),
+            };
+
+            var visualRoot = new TestRoot();
+            visualRoot.Child = target;
+            ApplyTemplates(target);
+
+            var item = tree[0].Children[1].Children[0];
+            var container = (TreeViewItem)target.ItemContainerGenerator.Index.ContainerFromItem(item);
+
+            Assert.NotNull(container);
+
+            target.SelectedItem = item;
+
+            Assert.True(container.IsSelected);
+        }
+
         [Fact]
         public void LogicalChildren_Should_Be_Set()
         {