From f91a788d18a40c187cd09e3516d86619869429c4 Mon Sep 17 00:00:00 2001
From: dif-sam <41672086+dif-sam@users.noreply.github.com>
Date: Thu, 13 Oct 2022 16:21:54 +0400
Subject: [PATCH 1/2] Suggested fix for #9173

trying to deffere request for BringIntoView, when TreeViewItem not ready yet.
---
 src/Avalonia.Controls/TreeViewItem.cs | 29 +++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/src/Avalonia.Controls/TreeViewItem.cs b/src/Avalonia.Controls/TreeViewItem.cs
index ada081b808..c2304abbc8 100644
--- a/src/Avalonia.Controls/TreeViewItem.cs
+++ b/src/Avalonia.Controls/TreeViewItem.cs
@@ -45,6 +45,8 @@ namespace Avalonia.Controls
         private IControl? _header;
         private bool _isExpanded;
         private int _level;
+        private bool _templateApplied;
+        private bool _deferredBringIntoViewFlag;
 
         /// <summary>
         /// Initializes static members of the <see cref="TreeViewItem"/> class.
@@ -136,15 +138,24 @@ namespace Avalonia.Controls
 
         protected virtual void OnRequestBringIntoView(RequestBringIntoViewEventArgs e)
         {
-            if (e.TargetObject == this && _header != null)
+            if (e.TargetObject == this)
             {
-                var m = _header.TransformToVisual(this);
+                if (!_templateApplied)
+                {
+                    _deferredBringIntoViewFlag = true;
+                    return;
+                }
 
-                if (m.HasValue)
+                if (_header != null)
                 {
-                    var bounds = new Rect(_header.Bounds.Size);
-                    var rect = bounds.TransformToAABB(m.Value);
-                    e.TargetRect = rect;
+                    var m = _header.TransformToVisual(this);
+
+                    if (m.HasValue)
+                    {
+                        var bounds = new Rect(_header.Bounds.Size);
+                        var rect = bounds.TransformToAABB(m.Value);
+                        e.TargetRect = rect;
+                    }
                 }
             }
         }
@@ -187,6 +198,12 @@ namespace Avalonia.Controls
         protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
         {
             _header = e.NameScope.Find<IControl>("PART_Header");
+            _templateApplied = true;
+            if (_deferredBringIntoViewFlag)
+            {
+                _deferredBringIntoViewFlag = false;
+                Dispatcher.UIThread.Post(this.BringIntoView); // must use the Dispatcher, otherwise the TreeView doesn't scroll
+            }
         }
 
         private static int CalculateDistanceFromLogicalParent<T>(ILogical? logical, int @default = -1) where T : class

From 65d39603fac9f963324158ab8d7c420565c5785b Mon Sep 17 00:00:00 2001
From: dif-sam <41672086+dif-sam@users.noreply.github.com>
Date: Thu, 13 Oct 2022 16:55:55 +0400
Subject: [PATCH 2/2] Forgotten namespase added to usings

---
 src/Avalonia.Controls/TreeViewItem.cs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/Avalonia.Controls/TreeViewItem.cs b/src/Avalonia.Controls/TreeViewItem.cs
index c2304abbc8..2f96e6911f 100644
--- a/src/Avalonia.Controls/TreeViewItem.cs
+++ b/src/Avalonia.Controls/TreeViewItem.cs
@@ -6,6 +6,7 @@ using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
 using Avalonia.Input;
 using Avalonia.LogicalTree;
+using Avalonia.Threading;
 
 namespace Avalonia.Controls
 {