From 8bb1349785fa3f68a920ccfc63936e378c4b0a93 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Thu, 1 Dec 2022 11:31:01 +0100
Subject: [PATCH] Setup TabItems.

---
 src/Avalonia.Controls/ItemsControl.cs | 25 +++++++++++++++++--------
 src/Avalonia.Controls/TabControl.cs   | 10 +++++++++-
 2 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/src/Avalonia.Controls/ItemsControl.cs b/src/Avalonia.Controls/ItemsControl.cs
index 7c24717a06..3de4017190 100644
--- a/src/Avalonia.Controls/ItemsControl.cs
+++ b/src/Avalonia.Controls/ItemsControl.cs
@@ -281,21 +281,30 @@ namespace Avalonia.Controls
             if (container == item)
                 return;
 
-            if (container is ContentControl cc)
+            if (container is HeaderedContentControl hcc)
             {
-                cc.SetValue(ContentControl.ContentProperty, item, BindingPriority.Template);
+                hcc.Content = item;
+
+                if (item is IHeadered headered)
+                    hcc.Header = headered.Header;
+                else if (item is not Visual)
+                    hcc.Header = item;
+
+                if (ItemTemplate is { } it)
+                    hcc.HeaderTemplate = it;
+            }
+            else if (container is ContentControl cc)
+            {
+                cc.Content = item;
                 if (ItemTemplate is { } it)
-                    cc.SetValue(ContentControl.ContentTemplateProperty, it, BindingPriority.Template);
+                    cc.ContentTemplate = it;
             }
             else if (container is ContentPresenter p)
             {
-                p.SetValue(ContentPresenter.ContentProperty, item, BindingPriority.Template);
+                p.Content = item;
                 if (ItemTemplate is { } it)
-                    p.SetValue(ContentPresenter.ContentTemplateProperty, it, BindingPriority.Template);
+                    p.ContentTemplate = it;
             }
-
-            if (ItemContainerTheme is not null)
-                container.SetValue(ThemeProperty, ItemContainerTheme, BindingPriority.Template);
         }
 
         /// <summary>
diff --git a/src/Avalonia.Controls/TabControl.cs b/src/Avalonia.Controls/TabControl.cs
index d08e0a61da..952a9e448c 100644
--- a/src/Avalonia.Controls/TabControl.cs
+++ b/src/Avalonia.Controls/TabControl.cs
@@ -171,7 +171,15 @@ namespace Avalonia.Controls
         protected internal override void PrepareContainerForItemOverride(Control element, object? item, int index)
         {
             base.PrepareContainerForItemOverride(element, item, index);
-            UpdateSelectedContent();
+            
+            if (element is HeaderedContentControl hcc && ContentTemplate is { } ct)
+                hcc.ContentTemplate = ct;
+
+            if (index == SelectedIndex && element is ContentControl container)
+            {
+                SelectedContentTemplate = container.ContentTemplate;
+                SelectedContent = container.Content;
+            }
         }
 
         protected override void ContainerIndexChangedOverride(Control container, int oldIndex, int newIndex)