From 6626a2e2182ae09d33c2c495f8b07019b96468d5 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Thu, 1 Dec 2022 10:33:44 +0100
Subject: [PATCH] Update TabControl on container index change.

---
 .../Presenters/PanelContainerGenerator.cs              |  2 +-
 src/Avalonia.Controls/TabControl.cs                    | 10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/Avalonia.Controls/Presenters/PanelContainerGenerator.cs b/src/Avalonia.Controls/Presenters/PanelContainerGenerator.cs
index 4a31017fbd..b080a9044f 100644
--- a/src/Avalonia.Controls/Presenters/PanelContainerGenerator.cs
+++ b/src/Avalonia.Controls/Presenters/PanelContainerGenerator.cs
@@ -96,7 +96,7 @@ namespace Avalonia.Controls.Presenters
                 var childCount = children.Count;
 
                 for (var i = index; i < childCount; ++i)
-                    generator.ItemContainerIndexChanged(children[i], i - count, i);
+                    generator.ItemContainerIndexChanged(children[i], i + count, i);
             }
 
             switch (e.Action)
diff --git a/src/Avalonia.Controls/TabControl.cs b/src/Avalonia.Controls/TabControl.cs
index 970d7de727..d08e0a61da 100644
--- a/src/Avalonia.Controls/TabControl.cs
+++ b/src/Avalonia.Controls/TabControl.cs
@@ -174,6 +174,16 @@ namespace Avalonia.Controls
             UpdateSelectedContent();
         }
 
+        protected override void ContainerIndexChangedOverride(Control container, int oldIndex, int newIndex)
+        {
+            base.ContainerIndexChangedOverride(container, oldIndex, newIndex);
+
+            var selectedIndex = SelectedIndex;
+            
+            if (selectedIndex == oldIndex || selectedIndex == newIndex)
+                UpdateSelectedContent();
+        }
+
         protected internal override void ClearContainerForItemOverride(Control element)
         {
             base.ClearContainerForItemOverride(element);