From cdf8d1f8b4810c86a2eaa56ade3a66dedd8efff5 Mon Sep 17 00:00:00 2001
From: wojciech krysiak <wojciech.krysiak@gmail.com>
Date: Mon, 23 Jul 2018 21:09:40 +0200
Subject: [PATCH 1/2] Fix For incorrect handling of
 NotifyCollectionChangedAction.Reset from IReactiveDerivedList<>

---
 src/Avalonia.Controls/Primitives/SelectingItemsControl.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
index eb3fbde8f2..c8425a0f80 100644
--- a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
+++ b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
@@ -376,7 +376,7 @@ namespace Avalonia.Controls.Primitives
                     break;
 
                 case NotifyCollectionChangedAction.Reset:
-                    SelectedIndex = IndexOf(e.NewItems, SelectedItem);
+                    SelectedIndex = IndexOf(Items, SelectedItem);
                     break;
             }
         }

From 03e859445113e8f2b3ed34383a893cb19ecf517e Mon Sep 17 00:00:00 2001
From: wojciech krysiak <wojciech.krysiak@gmail.com>
Date: Mon, 23 Jul 2018 22:32:13 +0200
Subject: [PATCH 2/2] Bug reproduction unit test

---
 .../Primitives/SelectingItemsControlTests.cs  | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs
index c7a3465ac4..14e1b15ebc 100644
--- a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs
@@ -3,6 +3,7 @@
 
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
+using System.Collections.Specialized;
 using System.Linq;
 using Avalonia.Collections;
 using Avalonia.Controls.Presenters;
@@ -13,6 +14,7 @@ using Avalonia.Input;
 using Avalonia.Interactivity;
 using Avalonia.Markup.Data;
 using Avalonia.UnitTests;
+using Moq;
 using Xunit;
 
 namespace Avalonia.Controls.UnitTests.Primitives
@@ -686,6 +688,26 @@ namespace Avalonia.Controls.UnitTests.Primitives
             Assert.Null(KeyboardNavigation.GetTabOnceActiveElement((InputElement)panel));
         }
 
+        [Fact]
+        public void Resetting_Items_Collection_Should_Retain_Selection()
+        {
+            var itemsMock = new Mock<List<string>>();
+            var itemsMockAsINCC = itemsMock.As<INotifyCollectionChanged>();
+
+            itemsMock.Object.AddRange(new[] { "Foo", "Bar", "Baz" });
+            var target = new SelectingItemsControl
+            {
+                Items = itemsMock.Object
+            };
+
+            target.SelectedIndex = 1;
+
+            itemsMockAsINCC.Raise(e => e.CollectionChanged += null, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
+
+            Assert.True(target.SelectedIndex == 1);
+        }
+
+
         private FuncControlTemplate Template()
         {
             return new FuncControlTemplate<SelectingItemsControl>(control =>