From dad0c4d18afc0462753b04d70bdb5b32ee6af335 Mon Sep 17 00:00:00 2001
From: Yoh Deadfall <yoh.deadfall@hotmail.com>
Date: Thu, 15 Oct 2020 20:24:03 +0300
Subject: [PATCH 1/2] Fixed invalid cast issue if source isn't visual

---
 .../Primitives/SelectingItemsControl.cs                | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
index 4317d795f1..19c2b3b8fa 100644
--- a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
+++ b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
@@ -356,17 +356,13 @@ namespace Avalonia.Controls.Primitives
         /// <returns>The container or null if the event did not originate in a container.</returns>
         protected IControl? GetContainerFromEventSource(IInteractive eventSource)
         {
-            var parent = (IVisual)eventSource;
-
-            while (parent != null)
+            for (var current = eventSource as IVisual; current != null; current = current.VisualParent)
             {
-                if (parent is IControl control && control.LogicalParent == this
-                                               && ItemContainerGenerator?.IndexFromContainer(control) != -1)
+                if (current is IControl control && control.LogicalParent == this &&
+                    ItemContainerGenerator?.IndexFromContainer(control) != -1)
                 {
                     return control;
                 }
-
-                parent = parent.VisualParent;
             }
 
             return null;

From 02e6a4ffa5c635f17e6eb51393f88b685599d148 Mon Sep 17 00:00:00 2001
From: Yoh Deadfall <yoh.deadfall@hotmail.com>
Date: Thu, 15 Oct 2020 20:24:57 +0300
Subject: [PATCH 2/2] Fixed nullability issues

---
 src/Avalonia.Controls/Primitives/SelectingItemsControl.cs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
index 19c2b3b8fa..d3e7751c4e 100644
--- a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
+++ b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
@@ -354,7 +354,7 @@ namespace Avalonia.Controls.Primitives
         /// </summary>
         /// <param name="eventSource">The control that raised the event.</param>
         /// <returns>The container or null if the event did not originate in a container.</returns>
-        protected IControl? GetContainerFromEventSource(IInteractive eventSource)
+        protected IControl? GetContainerFromEventSource(IInteractive? eventSource)
         {
             for (var current = eventSource as IVisual; current != null; current = current.VisualParent)
             {
@@ -666,7 +666,7 @@ namespace Avalonia.Controls.Primitives
         /// false.
         /// </returns>
         protected bool UpdateSelectionFromEventSource(
-            IInteractive eventSource,
+            IInteractive? eventSource,
             bool select = true,
             bool rangeModifier = false,
             bool toggleModifier = false,