Merge branch 'master' into visual-tree-traversal-v2

azure-pipelines.yml

@@ -34,9 +34,17 @@ jobs:
   pool:
     vmImage: 'macOS-10.14'
   steps:
-  - task: DotNetCoreInstaller@0
+  - task: UseDotNet@2
+    displayName: 'Use .NET Core SDK 3.0.x'
     inputs:
-      version: '2.1.403'
+      packageType: sdk
+      version: 3.0.x
+
+  - task: UseDotNet@2
+    displayName: 'Use .NET Core Runtime 2.1.x'
+    inputs:
+      packageType: runtime
+      version: 2.1.x
 
   - task: CmdLine@2
     displayName: 'Install Mono 5.18'

build/SharedVersion.props

@@ -2,7 +2,7 @@
   xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <Product>Avalonia</Product>
-    <Version>0.8.999</Version>
+    <Version>0.9.999</Version>
     <Copyright>Copyright 2019 &#169; The AvaloniaUI Project</Copyright>
     <PackageProjectUrl>https://avaloniaui.net</PackageProjectUrl>
     <RepositoryUrl>https://github.com/AvaloniaUI/Avalonia/</RepositoryUrl>

native/Avalonia.Native/inc/avalonia-native.h

@@ -212,6 +212,10 @@ AVNCOM(IAvnWindowBase, 02) : IUnknown
     virtual HRESULT GetSoftwareFramebuffer(AvnFramebuffer*ret) = 0;
     virtual HRESULT SetMainMenu(IAvnAppMenu* menu) = 0;
     virtual HRESULT ObtainMainMenu(IAvnAppMenu** retOut) = 0;
+    virtual HRESULT ObtainNSWindowHandle(void** retOut) = 0;
+    virtual HRESULT ObtainNSWindowHandleRetained(void** retOut) = 0;
+    virtual HRESULT ObtainNSViewHandle(void** retOut) = 0;
+    virtual HRESULT ObtainNSViewHandleRetained(void** retOut) = 0;
     virtual bool TryLock() = 0;
     virtual void Unlock() = 0;
 };

native/Avalonia.Native/src/OSX/app.mm

@@ -1,16 +1,25 @@
 #include "common.h"
 @interface AvnAppDelegate : NSObject<NSApplicationDelegate>
 @end
+
 extern NSApplicationActivationPolicy AvnDesiredActivationPolicy = NSApplicationActivationPolicyRegular;
 @implementation AvnAppDelegate
 - (void)applicationWillFinishLaunching:(NSNotification *)notification
 {
-    [[NSApplication sharedApplication] setActivationPolicy: AvnDesiredActivationPolicy];
+    if([[NSApplication sharedApplication] activationPolicy] != AvnDesiredActivationPolicy)
+    {
+        for (NSRunningApplication * app in [NSRunningApplication runningApplicationsWithBundleIdentifier:@"com.apple.dock"]) {
+            [app activateWithOptions:NSApplicationActivateIgnoringOtherApps];
+            break;
+        }
+        
+        [[NSApplication sharedApplication] setActivationPolicy: AvnDesiredActivationPolicy];
+    }
 }
 
 - (void)applicationDidFinishLaunching:(NSNotification *)notification
 {
-    [NSApp activateIgnoringOtherApps:true];
+    [[NSRunningApplication currentApplication] activateWithOptions:NSApplicationActivateIgnoringOtherApps];
 }
 
 @end
@@ -20,5 +29,4 @@ extern void InitializeAvnApp()
     NSApplication* app = [NSApplication sharedApplication];
     id delegate = [AvnAppDelegate new];
     [app setDelegate:delegate];
-    
 }

native/Avalonia.Native/src/OSX/window.mm

@@ -83,6 +83,54 @@ public:
         [Window setContentView: View];
     }
     
+    virtual HRESULT ObtainNSWindowHandle(void** ret) override
+    {
+        if (ret == nullptr)
+        {
+            return E_POINTER;
+        }
+        
+        *ret =  (__bridge void*)Window;
+        
+        return S_OK;
+    }
+    
+    virtual HRESULT ObtainNSWindowHandleRetained(void** ret) override
+    {
+        if (ret == nullptr)
+        {
+            return E_POINTER;
+        }
+        
+        *ret =  (__bridge_retained void*)Window;
+        
+        return S_OK;
+    }
+    
+    virtual HRESULT ObtainNSViewHandle(void** ret) override
+    {
+        if (ret == nullptr)
+        {
+            return E_POINTER;
+        }
+        
+        *ret =  (__bridge void*)View;
+        
+        return S_OK;
+    }
+    
+    virtual HRESULT ObtainNSViewHandleRetained(void** ret) override
+    {
+        if (ret == nullptr)
+        {
+            return E_POINTER;
+        }
+        
+        *ret =  (__bridge_retained void*)View;
+        
+        return S_OK;
+    }
+    
     virtual AvnWindow* GetNSWindow() override
     {
         return Window;

samples/ControlCatalog/App.xaml.cs

@@ -1,6 +1,4 @@
-using System;
 using Avalonia;
-using Avalonia.Controls;
 using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Markup.Xaml;
 
@@ -19,7 +17,7 @@ namespace ControlCatalog
                 desktopLifetime.MainWindow = new MainWindow();
             else if (ApplicationLifetime is ISingleViewApplicationLifetime singleViewLifetime)
                 singleViewLifetime.MainView = new MainView();
-            
+
             base.OnFrameworkInitializationCompleted();
         }
     }

src/Avalonia.Base/Platform/IMacOSTopLevelPlatformHandle.cs

@@ -0,0 +1,15 @@
+// Copyright (c) The Avalonia Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+
+namespace Avalonia.Platform
+{
+    public interface IMacOSTopLevelPlatformHandle
+    {
+        IntPtr NSView { get; }
+        IntPtr GetNSViewRetained();
+        IntPtr NSWindow { get; }
+        IntPtr GetNSWindowRetained();
+    }
+}

src/Avalonia.Controls/Application.cs

@@ -32,7 +32,7 @@ namespace Avalonia
     /// method.
     /// - Tracks the lifetime of the application.
     /// </remarks>
-    public class Application : AvaloniaObject, IGlobalDataTemplates, IGlobalStyles, IStyleRoot, IResourceNode
+    public class Application : AvaloniaObject, IDataContextProvider, IGlobalDataTemplates, IGlobalStyles, IStyleRoot, IResourceNode
     {
         /// <summary>
         /// The application-global data templates.
@@ -45,6 +45,12 @@ namespace Avalonia
         private Styles _styles;
         private IResourceDictionary _resources;
 
+        /// <summary>
+        /// Defines the <see cref="DataContext"/> property.
+        /// </summary>
+        public static readonly StyledProperty<object> DataContextProperty =
+            StyledElement.DataContextProperty.AddOwner<Application>();
+
         /// <inheritdoc/>
         public event EventHandler<ResourcesChangedEventArgs> ResourcesChanged;
 
@@ -56,6 +62,19 @@ namespace Avalonia
             Name = "Avalonia Application";
         }
 
+        /// <summary>
+        /// Gets or sets the Applications's data context.
+        /// </summary>
+        /// <remarks>
+        /// The data context property specifies the default object that will
+        /// be used for data binding.
+        /// </remarks>
+        public object DataContext
+        {
+            get { return GetValue(DataContextProperty); }
+            set { SetValue(DataContextProperty, value); }
+        }
+
         /// <summary>
         /// Gets the current instance of the <see cref="Application"/> class.
         /// </summary>

src/Avalonia.Controls/Generators/ITreeItemContainerGenerator.cs

@@ -12,5 +12,10 @@ namespace Avalonia.Controls.Generators
         /// Gets the container index for the tree.
         /// </summary>
         TreeContainerIndex Index { get; }
+
+        /// <summary>
+        /// Updates the index based on the parent <see cref="TreeView"/>.
+        /// </summary>
+        void UpdateIndex();
     }
 }

src/Avalonia.Controls/Generators/TreeItemContainerGenerator.cs

@@ -3,8 +3,10 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Avalonia.Controls.Templates;
 using Avalonia.Data;
+using Avalonia.LogicalTree;
 
 namespace Avalonia.Controls.Generators
 {
@@ -15,6 +17,8 @@ namespace Avalonia.Controls.Generators
     public class TreeItemContainerGenerator<T> : ItemContainerGenerator<T>, ITreeItemContainerGenerator
         where T : class, IControl, new()
     {
+        private TreeView _treeView;
+
         /// <summary>
         /// Initializes a new instance of the <see cref="TreeItemContainerGenerator{T}"/> class.
         /// </summary>
@@ -23,31 +27,28 @@ namespace Avalonia.Controls.Generators
         /// <param name="contentTemplateProperty">The container's ContentTemplate property.</param>
         /// <param name="itemsProperty">The container's Items property.</param>
         /// <param name="isExpandedProperty">The container's IsExpanded property.</param>
-        /// <param name="index">The container index for the tree</param>
         public TreeItemContainerGenerator(
             IControl owner,
             AvaloniaProperty contentProperty,
             AvaloniaProperty contentTemplateProperty,
             AvaloniaProperty itemsProperty,
-            AvaloniaProperty isExpandedProperty,
-            TreeContainerIndex index)
+            AvaloniaProperty isExpandedProperty)
             : base(owner, contentProperty, contentTemplateProperty)
         {
             Contract.Requires<ArgumentNullException>(owner != null);
             Contract.Requires<ArgumentNullException>(contentProperty != null);
             Contract.Requires<ArgumentNullException>(itemsProperty != null);
             Contract.Requires<ArgumentNullException>(isExpandedProperty != null);
-            Contract.Requires<ArgumentNullException>(index != null);
 
             ItemsProperty = itemsProperty;
             IsExpandedProperty = isExpandedProperty;
-            Index = index;
+            UpdateIndex();
         }
 
         /// <summary>
         /// Gets the container index for the tree.
         /// </summary>
-        public TreeContainerIndex Index { get; }
+        public TreeContainerIndex Index { get; private set; }
 
         /// <summary>
         /// Gets the item container's Items property.
@@ -70,7 +71,7 @@ namespace Avalonia.Controls.Generators
             }
             else if (container != null)
             {
-                Index.Add(item, container);
+                Index?.Add(item, container);
                 return container;
             }
             else
@@ -92,7 +93,7 @@ namespace Avalonia.Controls.Generators
                     result.DataContext = item;
                 }
 
-                Index.Add(item, result);
+                Index?.Add(item, result);
 
                 return result;
             }
@@ -101,24 +102,50 @@ namespace Avalonia.Controls.Generators
         public override IEnumerable<ItemContainerInfo> Clear()
         {
             var items = base.Clear();
-            Index.Remove(0, items);
+            Index?.Remove(0, items);
             return items;
         }
 
         public override IEnumerable<ItemContainerInfo> Dematerialize(int startingIndex, int count)
         {
-            Index.Remove(startingIndex, GetContainerRange(startingIndex, count));
+            Index?.Remove(startingIndex, GetContainerRange(startingIndex, count));
             return base.Dematerialize(startingIndex, count);
         }
 
         public override IEnumerable<ItemContainerInfo> RemoveRange(int startingIndex, int count)
         {
-            Index.Remove(startingIndex, GetContainerRange(startingIndex, count));
+            Index?.Remove(startingIndex, GetContainerRange(startingIndex, count));
             return base.RemoveRange(startingIndex, count);
         }
 
         public override bool TryRecycle(int oldIndex, int newIndex, object item) => false;
 
+        public void UpdateIndex()
+        {
+            if (Owner is TreeView treeViewOwner && Index == null)
+            {
+                Index = new TreeContainerIndex();
+                _treeView = treeViewOwner;
+            }
+            else if (Owner.IsAttachedToLogicalTree)
+            {
+                var treeView = Owner.GetSelfAndLogicalAncestors().OfType<TreeView>().FirstOrDefault();
+                
+                if (treeView != _treeView)
+                {
+                    Clear();
+                    Index = treeView?.ItemContainerGenerator?.Index;
+                    _treeView = treeView;
+                }
+            }
+            else
+            {
+                Clear();
+                Index = null;
+                _treeView = null;
+            }
+        }
+
         class WrapperTreeDataTemplate : ITreeDataTemplate
         {
             private readonly IDataTemplate _inner;

src/Avalonia.Controls/Primitives/RangeBase.cs

@@ -75,7 +75,10 @@ namespace Avalonia.Controls.Primitives
 
             set
             {
-                ValidateDouble(value, "Minimum");
+                if (!ValidateDouble(value))
+                {
+                    return;
+                }
 
                 if (IsInitialized)
                 {
@@ -102,7 +105,10 @@ namespace Avalonia.Controls.Primitives
 
             set
             {
-                ValidateDouble(value, "Maximum");
+                if (!ValidateDouble(value))
+                {
+                    return;
+                }
 
                 if (IsInitialized)
                 {
@@ -129,7 +135,10 @@ namespace Avalonia.Controls.Primitives
 
             set
             {
-                ValidateDouble(value, "Value");
+                if (!ValidateDouble(value))
+                {
+                    return;
+                }
 
                 if (IsInitialized)
                 {
@@ -164,16 +173,12 @@ namespace Avalonia.Controls.Primitives
         }
 
         /// <summary>
-        /// Throws an exception if the double value is NaN or Inf.
+        /// Checks if the double value is not inifinity nor NaN.
         /// </summary>
         /// <param name="value">The value.</param>
-        /// <param name="property">The name of the property being set.</param>
-        private static void ValidateDouble(double value, string property)
+        private static bool ValidateDouble(double value)
         {
-            if (double.IsInfinity(value) || double.IsNaN(value))
-            {
-                throw new ArgumentException($"{value} is not a valid value for {property}.");
-            }
+            return !double.IsInfinity(value) || !double.IsNaN(value);
         }
 
         /// <summary>

src/Avalonia.Controls/TopLevel.cs

@@ -266,6 +266,12 @@ namespace Avalonia.Controls
         /// </summary>
         protected virtual void HandleClosed()
         {
+            var logicalArgs = new LogicalTreeAttachmentEventArgs(this);
+            ((ILogical)this).NotifyDetachedFromLogicalTree(logicalArgs);
+
+            var visualArgs = new VisualTreeAttachmentEventArgs(this, this);
+            OnDetachedFromVisualTreeCore(visualArgs);
+
             (this as IInputRoot).MouseDevice?.TopLevelClosed(this);
             PlatformImpl = null;
             OnClosed(EventArgs.Empty);

src/Avalonia.Controls/TreeView.cs

@@ -393,8 +393,7 @@ namespace Avalonia.Controls
                 TreeViewItem.HeaderProperty,
                 TreeViewItem.ItemTemplateProperty,
                 TreeViewItem.ItemsProperty,
-                TreeViewItem.IsExpandedProperty,
-                new TreeContainerIndex());
+                TreeViewItem.IsExpandedProperty);
             result.Index.Materialized += ContainerMaterialized;
             return result;
         }

src/Avalonia.Controls/TreeViewItem.cs

@@ -98,17 +98,18 @@ namespace Avalonia.Controls
                 TreeViewItem.HeaderProperty,
                 TreeViewItem.ItemTemplateProperty,
                 TreeViewItem.ItemsProperty,
-                TreeViewItem.IsExpandedProperty,
-                _treeView?.ItemContainerGenerator.Index ?? new TreeContainerIndex());
+                TreeViewItem.IsExpandedProperty);
         }
 
         /// <inheritdoc/>
         protected override void OnAttachedToLogicalTree(LogicalTreeAttachmentEventArgs e)
         {
             base.OnAttachedToLogicalTree(e);
+            
             _treeView = this.GetLogicalAncestors().OfType<TreeView>().FirstOrDefault();
-
+            
             Level = CalculateDistanceFromLogicalParent<TreeView>(this) - 1;
+            ItemContainerGenerator.UpdateIndex();
 
             if (ItemTemplate == null && _treeView?.ItemTemplate != null)
             {
@@ -119,7 +120,7 @@ namespace Avalonia.Controls
         protected override void OnDetachedFromLogicalTree(LogicalTreeAttachmentEventArgs e)
         {
             base.OnDetachedFromLogicalTree(e);
-            ItemContainerGenerator.Clear();
+            ItemContainerGenerator.UpdateIndex();
         }
 
         protected virtual void OnRequestBringIntoView(RequestBringIntoViewEventArgs e)

src/Avalonia.Controls/Window.cs

@@ -336,7 +336,6 @@ namespace Avalonia.Controls
                 if (close)
                 {
                     PlatformImpl?.Dispose();
-                    HandleClosed();
                 }
             }
         }

src/Avalonia.Input/InputElement.cs

@@ -342,7 +342,7 @@ namespace Avalonia.Input
         }
 
         /// <summary>
-        /// Gets or sets a value indicating whether the control is focused.
+        /// Gets a value indicating whether the control is focused.
         /// </summary>
         public bool IsFocused
         {
@@ -360,7 +360,7 @@ namespace Avalonia.Input
         }
 
         /// <summary>
-        /// Gets or sets a value indicating whether the pointer is currently over the control.
+        /// Gets a value indicating whether the pointer is currently over the control.
         /// </summary>
         public bool IsPointerOver
         {

src/Avalonia.Native/WindowImplBase.cs

@@ -16,6 +16,34 @@ using Avalonia.Threading;
 
 namespace Avalonia.Native
 {
+    public class MacOSTopLevelWindowHandle : IPlatformHandle, IMacOSTopLevelPlatformHandle
+    {
+        IAvnWindowBase _native;
+
+        public MacOSTopLevelWindowHandle(IAvnWindowBase native)
+        {
+            _native = native;
+        }
+
+        public IntPtr Handle => NSWindow;
+
+        public string HandleDescriptor => "NSWindow";
+
+        public IntPtr NSView => _native.ObtainNSViewHandle();
+
+        public IntPtr NSWindow => _native.ObtainNSWindowHandle();
+
+        public IntPtr GetNSViewRetained()
+        {
+            return _native.ObtainNSViewHandleRetained();
+        }
+
+        public IntPtr GetNSWindowRetained()
+        {
+            return _native.ObtainNSWindowHandleRetained();
+        }
+    }
+
     public abstract class WindowBaseImpl : IWindowBaseImpl,
         IFramebufferPlatformSurface
     {
@@ -45,6 +73,9 @@ namespace Avalonia.Native
         protected void Init(IAvnWindowBase window, IAvnScreens screens)
         {
             _native = window;
+
+            Handle = new MacOSTopLevelWindowHandle(window);
+            
             _glSurface = new GlPlatformSurface(window);
             Screen = new ScreenImpl(screens);
             _savedLogicalSize = ClientSize;
@@ -349,6 +380,6 @@ namespace Avalonia.Native
 
         }
 
-        public IPlatformHandle Handle => new PlatformHandle(IntPtr.Zero, "NOT SUPPORTED");
+        public IPlatformHandle Handle { get; private set; }
     }
 }

src/Avalonia.Styling/IDataContextProvider.cs

@@ -0,0 +1,13 @@
+namespace Avalonia
+{
+    /// <summary>
+    /// Defines an element with a data context that can be used for binding.
+    /// </summary>
+    public interface IDataContextProvider : IAvaloniaObject
+    {
+        /// <summary>
+        /// Gets or sets the element's data context.
+        /// </summary>
+        object DataContext { get; set; }
+    }
+}

src/Avalonia.Styling/IStyledElement.cs

@@ -10,7 +10,8 @@ namespace Avalonia
         IStyleHost,
         ILogical,
         IResourceProvider,
-        IResourceNode
+        IResourceNode,
+        IDataContextProvider
     {
         /// <summary>
         /// Occurs when the control has finished initialization.
@@ -27,11 +28,6 @@ namespace Avalonia
         /// </summary>
         new Classes Classes { get; set; }
 
-        /// <summary>
-        /// Gets or sets the control's data context.
-        /// </summary>
-        object DataContext { get; set; }
-
         /// <summary>
         /// Gets the control's logical parent.
         /// </summary>

src/Avalonia.Styling/StyledElement.cs

@@ -24,7 +24,7 @@ namespace Avalonia
     /// - Implements <see cref="ILogical"/> to form part of a logical tree.
     /// - A collection of class strings for custom styling.
     /// </summary>
-    public class StyledElement : Animatable, IStyledElement, ISetLogicalParent, ISetInheritanceParent
+    public class StyledElement : Animatable, IDataContextProvider, IStyledElement, ISetLogicalParent, ISetInheritanceParent
     {
         /// <summary>
         /// Defines the <see cref="DataContext"/> property.
@@ -288,7 +288,7 @@ namespace Avalonia
                     var list = new AvaloniaList<ILogical>
                     {
                         ResetBehavior = ResetBehavior.Remove,
-                        Validate = ValidateLogicalChild
+                        Validate = logical => ValidateLogicalChild(logical)
                     };
                     list.CollectionChanged += LogicalChildrenCollectionChanged;
                     _logicalChildren = list;

src/Avalonia.Visuals/Visual.cs

@@ -120,7 +120,7 @@ namespace Avalonia
         {
             var visualChildren = new AvaloniaList<IVisual>();
             visualChildren.ResetBehavior = ResetBehavior.Remove;
-            visualChildren.Validate = ValidateVisualChild;
+            visualChildren.Validate = visual => ValidateVisualChild(visual);
             visualChildren.CollectionChanged += VisualChildrenChanged;
             VisualChildren = visualChildren;
         }

src/Markup/Avalonia.Markup.Xaml/MarkupExtensions/BindingExtension.cs

@@ -52,6 +52,13 @@ namespace Avalonia.Markup.Xaml.MarkupExtensions
             // the context.
             object anchor = context.GetFirstParent<IControl>();
 
+            if(anchor is null)
+            {
+                // Try to find IDataContextProvider, this was added to allow us to find
+                // a datacontext for Application class when using NativeMenuItems.
+                anchor = context.GetFirstParent<IDataContextProvider>();
+            }
+
             // If a control was not found, then try to find the highest-level style as the XAML
             // file could be a XAML file containing only styles.
             return anchor ??

src/Markup/Avalonia.Markup/Data/Binding.cs

@@ -231,9 +231,9 @@ namespace Avalonia.Data
         {
             Contract.Requires<ArgumentNullException>(target != null);
 
-            if (!(target is IStyledElement))
+            if (!(target is IDataContextProvider))
             {
-                target = anchor as IStyledElement;
+                target = anchor as IDataContextProvider;
 
                 if (target == null)
                 {

tests/Avalonia.Controls.UnitTests/Primitives/RangeBaseTests.cs

@@ -82,22 +82,6 @@ namespace Avalonia.Controls.UnitTests.Primitives
             Assert.Equal(50, target.Value);
         }
 
-        [Fact]
-        public void Properties_Should_Not_Accept_Nan_And_Inifinity()
-        {
-            var target = new TestRange();
-
-            Assert.Throws<ArgumentException>(() => target.Minimum = double.NaN);
-            Assert.Throws<ArgumentException>(() => target.Minimum = double.PositiveInfinity);
-            Assert.Throws<ArgumentException>(() => target.Minimum = double.NegativeInfinity);
-            Assert.Throws<ArgumentException>(() => target.Maximum = double.NaN);
-            Assert.Throws<ArgumentException>(() => target.Maximum = double.PositiveInfinity);
-            Assert.Throws<ArgumentException>(() => target.Maximum = double.NegativeInfinity);
-            Assert.Throws<ArgumentException>(() => target.Value = double.NaN);
-            Assert.Throws<ArgumentException>(() => target.Value = double.PositiveInfinity);
-            Assert.Throws<ArgumentException>(() => target.Value = double.NegativeInfinity);
-        }
-
         [Theory]
         [InlineData(true)]
         [InlineData(false)]

tests/Avalonia.Controls.UnitTests/TreeViewTests.cs

@@ -10,6 +10,7 @@ using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Templates;
 using Avalonia.Data;
 using Avalonia.Data.Core;
+using Avalonia.Diagnostics;
 using Avalonia.Input;
 using Avalonia.Input.Platform;
 using Avalonia.Interactivity;
@@ -33,6 +34,8 @@ namespace Avalonia.Controls.UnitTests
                 Items = CreateTestTreeData(),
             };
 
+            var root = new TestRoot(target);
+
             CreateNodeDataTemplate(target);
             ApplyTemplates(target);
 
@@ -77,6 +80,8 @@ namespace Avalonia.Controls.UnitTests
                 Items = CreateTestTreeData(),
             };
 
+            var root = new TestRoot(target);
+
             CreateNodeDataTemplate(target);
             ApplyTemplates(target);
 
@@ -527,6 +532,8 @@ namespace Avalonia.Controls.UnitTests
                 Items = data,
             };
 
+            var root = new TestRoot(target);
+
             CreateNodeDataTemplate(target);
             ApplyTemplates(target);
 
@@ -893,6 +900,37 @@ namespace Avalonia.Controls.UnitTests
             Assert.Equal(2, GetItem(target, 0, 1, 0).Level);
         }
 
+        [Fact]
+        public void Adding_Node_To_Removed_And_ReAdded_Parent_Should_Not_Crash()
+        {
+            // Issue #2985
+            var tree = CreateTestTreeData();
+            var target = new TreeView
+            {
+                Template = CreateTreeViewTemplate(),
+                Items = tree,
+            };
+
+            var visualRoot = new TestRoot();
+            visualRoot.Child = target;
+
+            CreateNodeDataTemplate(target);
+            ApplyTemplates(target);
+            ExpandAll(target);
+
+            var parent = tree[0];
+            var node = parent.Children[1];
+
+            parent.Children.Remove(node);
+            parent.Children.Add(node);
+
+            var item = target.ItemContainerGenerator.Index.ContainerFromItem(node);
+            ApplyTemplates(new[] { item });
+
+            // #2985 causes ArgumentException here.
+            node.Children.Add(new Node());
+        }
+
         [Fact]
         public void Auto_Expanding_In_Style_Should_Not_Break_Range_Selection()
         {

tests/Avalonia.Controls.UnitTests/WindowTests.cs

@@ -228,8 +228,7 @@ namespace Avalonia.Controls.UnitTests
         {
             using (UnitTestApplication.Start(TestServices.StyledWindow))
             {
-                var windowImpl = Mock.Of<IWindowImpl>(x => x.Scaling == 1);
-                var target = new Window(windowImpl);
+                var target = new Window();
 
                 target.Show();
                 target.Close();

tests/Avalonia.UnitTests/MockWindowingPlatform.cs

@@ -28,6 +28,10 @@ namespace Avalonia.UnitTests
                 return CreatePopupMock().Object;
 
             });
+            mock.Setup(x => x.Dispose()).Callback(() =>
+            {
+                mock.Object.Closed?.Invoke();
+            });
             PixelPoint pos = default;
             mock.SetupGet(x => x.Position).Returns(() => pos);
             mock.Setup(x => x.Move(It.IsAny<PixelPoint>())).Callback(new Action<PixelPoint>(np => pos = np));