From 520dc16c2a879f4806e1ce8e7580914d011035ab Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Thu, 6 Feb 2020 16:12:13 +0100
Subject: [PATCH 1/2] Added failing test.

Clearing a nested selection doesn't raise `SelectionChanged`.
---
 .../SelectionModelTests.cs                    | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/tests/Avalonia.Controls.UnitTests/SelectionModelTests.cs b/tests/Avalonia.Controls.UnitTests/SelectionModelTests.cs
index c76dc890a9..040448d6fd 100644
--- a/tests/Avalonia.Controls.UnitTests/SelectionModelTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/SelectionModelTests.cs
@@ -1184,6 +1184,29 @@ namespace Avalonia.Controls.UnitTests
             Assert.Equal(1, raised);
         }
 
+        [Fact]
+        public void Clearing_Nested_Selection_Raises_SelectionChanged()
+        {
+            var target = new SelectionModel();
+            var raised = 0;
+
+            target.Source = CreateNestedData(1, 2, 3);
+            target.Select(1, 1);
+
+            target.SelectionChanged += (s, e) =>
+            {
+                Assert.Equal(new[] { new IndexPath(1, 1) }, e.DeselectedIndices);
+                Assert.Equal(new object[] { 4 }, e.DeselectedItems);
+                Assert.Empty(e.SelectedIndices);
+                Assert.Empty(e.SelectedItems);
+                ++raised;
+            };
+
+            target.ClearSelection();
+
+            Assert.Equal(1, raised);
+        }
+
         [Fact]
         public void Changing_Source_Raises_SelectionChanged()
         {

From e3d11a82888ba8eef2f928a12e857c9683f0ec3e Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Thu, 6 Feb 2020 16:12:43 +0100
Subject: [PATCH 2/2] Fix clearing nested selection not raising
 SelectionChanged.

---
 src/Avalonia.Controls/SelectionModel.cs |  2 ++
 src/Avalonia.Controls/SelectionNode.cs  | 23 +++++++++++++----------
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/src/Avalonia.Controls/SelectionModel.cs b/src/Avalonia.Controls/SelectionModel.cs
index c8ebf59032..5d787fb1ca 100644
--- a/src/Avalonia.Controls/SelectionModel.cs
+++ b/src/Avalonia.Controls/SelectionModel.cs
@@ -324,6 +324,7 @@ namespace Avalonia.Controls
         public void Dispose()
         {
             ClearSelection(resetAnchor: false);
+            _rootNode.Cleanup();
             _rootNode.Dispose();
             _selectedIndicesCached = null;
             _selectedItemsCached = null;
@@ -764,6 +765,7 @@ namespace Avalonia.Controls
             }
 
             OnSelectionChanged(e);
+            _rootNode.Cleanup();
         }
 
         internal class SelectedItemInfo : ISelectedItemInfo
diff --git a/src/Avalonia.Controls/SelectionNode.cs b/src/Avalonia.Controls/SelectionNode.cs
index 04144e1ed0..81177f06ca 100644
--- a/src/Avalonia.Controls/SelectionNode.cs
+++ b/src/Avalonia.Controls/SelectionNode.cs
@@ -342,6 +342,19 @@ namespace Avalonia.Controls
             }
         }
 
+        public void Cleanup()
+        {
+            foreach (var child in _childrenNodes)
+            {
+                child?.Cleanup();
+
+                if (child?.SelectedCount == 0)
+                {
+                    child.Dispose();
+                }
+            }
+        }
+
         public bool Select(int index, bool select)
         {
             return Select(index, select, raiseOnSelectionChanged: true);
@@ -453,16 +466,6 @@ namespace Avalonia.Controls
 
             SelectedCount = 0;
             AnchorIndex = -1;
-
-            // This will throw away all the children SelectionNodes
-            // causing them to be unhooked from their data source. This
-            // essentially cleans up the tree.
-            foreach (var child in _childrenNodes)
-            {
-                child?.Dispose();
-            }
-
-            _childrenNodes.Clear();
         }
 
         private bool Select(int index, bool select, bool raiseOnSelectionChanged)