From 6b13c81527796fd1be7792badd0ce1faadf6e222 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@users.noreply.github.com>
Date: Sat, 22 Apr 2023 00:42:43 +0200
Subject: [PATCH 1/3] Raise WindowBase.Resized before SizeChanged.

---
 src/Avalonia.Controls/WindowBase.cs | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/src/Avalonia.Controls/WindowBase.cs b/src/Avalonia.Controls/WindowBase.cs
index c2523207e4..463eda4f3c 100644
--- a/src/Avalonia.Controls/WindowBase.cs
+++ b/src/Avalonia.Controls/WindowBase.cs
@@ -232,14 +232,16 @@ namespace Avalonia.Controls
         {
             FrameSize = PlatformImpl?.FrameSize;
 
-            if (ClientSize != clientSize)
+            var clientSizeChanged = ClientSize != clientSize;
+
+            ClientSize = clientSize;
+            OnResized(new WindowResizedEventArgs(clientSize, reason));
+
+            if (clientSizeChanged)
             {
-                ClientSize = clientSize;
                 LayoutManager.ExecuteLayoutPass();
                 Renderer.Resized(clientSize);
             }
-
-            OnResized(new WindowResizedEventArgs(clientSize, reason));
         }
 
         /// <summary>

From 9f3dbfff6a3e66ac4284edf0332b8168df1d7b7e Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@users.noreply.github.com>
Date: Tue, 25 Apr 2023 22:31:44 +0200
Subject: [PATCH 2/3] Added docs to clarify difference with SizeChanged.

---
 src/Avalonia.Controls/WindowBase.cs | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/Avalonia.Controls/WindowBase.cs b/src/Avalonia.Controls/WindowBase.cs
index 463eda4f3c..0017630a75 100644
--- a/src/Avalonia.Controls/WindowBase.cs
+++ b/src/Avalonia.Controls/WindowBase.cs
@@ -83,6 +83,19 @@ namespace Avalonia.Controls
         /// <summary>
         /// Occurs when the window is resized.
         /// </summary>
+        /// <remarks>
+        /// Although this event is similar to the <see cref="Control.SizeChanged"/> event, they are
+        /// conceptually different:
+        /// 
+        /// - <see cref="Resized"/> is a window-level event, fired when a resize notification arrives
+        ///   from the platform windowing subsystem. The event args contain details of the source of
+        ///   the resize event in the <see cref="WindowResizedEventArgs.Reason"/> property. This
+        ///   event is raised before layout has been run on the window's content.
+        /// - <see cref="Control.SizeChanged"/> is a layout-level event, fired when a layout pass
+        ///   completes on a control. <see cref="Control.SizeChanged"/> is present on all controls
+        ///   and is fired when the control's size changes for any reason, including a
+        ///   <see cref="Resized"/> event in the case of a Window.
+        /// </remarks>
         public event EventHandler<WindowResizedEventArgs>? Resized;
 
         public new IWindowBaseImpl? PlatformImpl => (IWindowBaseImpl?) base.PlatformImpl;

From 6c8afc714c2fa1a4797ab2d2a914c1645f086c00 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@users.noreply.github.com>
Date: Tue, 25 Apr 2023 22:54:52 +0200
Subject: [PATCH 3/3] Correctly handle TreeViewPage data context change.

Fixes #11120.
---
 .../Diagnostics/Views/TreePageView.xaml.cs    | 28 ++++++++++++-------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/src/Avalonia.Diagnostics/Diagnostics/Views/TreePageView.xaml.cs b/src/Avalonia.Diagnostics/Diagnostics/Views/TreePageView.xaml.cs
index 66be6b5041..b0aea64994 100644
--- a/src/Avalonia.Diagnostics/Diagnostics/Views/TreePageView.xaml.cs
+++ b/src/Avalonia.Diagnostics/Diagnostics/Views/TreePageView.xaml.cs
@@ -39,16 +39,6 @@ namespace Avalonia.Diagnostics.Views
             AdornerLayer.SetIsClipEnabled(_adorner, false);
         }
 
-        protected override void OnDataContextChanged(EventArgs e)
-        {
-            base.OnDataContextChanged(e);
-
-            ((TreePageViewModel)DataContext!).ClipboardCopyRequested += (sender, s) =>
-            {
-                TopLevel.GetTopLevel(this)?.Clipboard?.SetTextAsync(s);
-            };
-        }
-
         protected void AddAdorner(object? sender, PointerEventArgs e)
         {
             var node = (TreeNode?)((Control)sender!).DataContext;
@@ -108,9 +98,27 @@ namespace Avalonia.Diagnostics.Views
             _currentLayer = null;
         }
 
+        protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)
+        {
+            base.OnPropertyChanged(change);
+
+            if (change.Property == DataContextProperty)
+            {
+                if (change.GetOldValue<object?>() is TreePageViewModel oldViewModel)
+                    oldViewModel.ClipboardCopyRequested -= OnClipboardCopyRequested;
+                if (change.GetNewValue<object?>() is TreePageViewModel newViewModel)
+                    newViewModel.ClipboardCopyRequested += OnClipboardCopyRequested;
+            }
+        }
+
         private void InitializeComponent()
         {
             AvaloniaXamlLoader.Load(this);
         }
+
+        private void OnClipboardCopyRequested(object? sender, string e)
+        {
+            TopLevel.GetTopLevel(this)?.Clipboard?.SetTextAsync(e);
+        }
     }
 }