Apply requested changes and some more clean up.

src/Avalonia.Diagnostics/Models/ChainLink.cs → src/Avalonia.Diagnostics/Models/EventChainLink.cs

@@ -1,13 +1,24 @@
-using System;
-using System.Collections.Generic;
-using System.Text;
+// 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;
 using Avalonia.Interactivity;
 
 namespace Avalonia.Diagnostics.Models
 {
-    internal class ChainLink
+    internal class EventChainLink
     {
-        public object Handler { get; private set; }
+        public EventChainLink(object handler, bool handled, RoutingStrategies route)
+        {
+            Contract.Requires<ArgumentNullException>(handler != null);
+
+            this.Handler = handler;
+            this.Handled = handled;
+            this.Route = route;
+        }
+
+        public object Handler { get; }
+
         public string HandlerName
         {
             get
@@ -19,16 +30,9 @@ namespace Avalonia.Diagnostics.Models
                 return Handler.GetType().Name;
             }
         }
-        public bool Handled { get; private set; }
-        public RoutingStrategies Route { get; private set; }
 
-        public ChainLink(object handler, bool handled, RoutingStrategies route)
-        {
-            Contract.Requires<ArgumentNullException>(handler != null);
+        public bool Handled { get; }
 
-            this.Handler = handler;
-            this.Handled = handled;
-            this.Route = route;
-        }
+        public RoutingStrategies Route { get; }
     }
 }

src/Avalonia.Diagnostics/ViewModels/EventEntryTreeNode.cs

@@ -1,97 +0,0 @@
-// 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;
-using Avalonia.Diagnostics.Models;
-using Avalonia.Interactivity;
-using Avalonia.Threading;
-using Avalonia.VisualTree;
-
-namespace Avalonia.Diagnostics.ViewModels
-{
-    internal class EventEntryTreeNode : EventTreeNode
-    {
-        RoutedEvent _event;
-        EventsViewModel _parentViewModel;
-        bool _isRegistered;
-        FiredEvent _currentEvent;
-
-        public EventEntryTreeNode(ControlTreeNode parent, RoutedEvent @event, EventsViewModel vm)
-            : base(parent, @event.Name)
-        {
-            Contract.Requires<ArgumentNullException>(@event != null);
-            Contract.Requires<ArgumentNullException>(vm != null);
-
-            this._event = @event;
-            this._parentViewModel = vm;
-        }
-
-        public override bool? IsEnabled
-        {
-            get => base.IsEnabled;
-            set
-            {
-                if (base.IsEnabled != value)
-                {
-                    base.IsEnabled = value;
-                    UpdateTracker();
-                    if (Parent != null && _updateParent)
-                    {
-                        try
-                        {
-                            Parent._updateChildren = false;
-                            Parent.UpdateChecked();
-                        }
-                        finally
-                        {
-                            Parent._updateChildren = true;
-                        }
-                    }
-                }
-            }
-        }
-
-        private void UpdateTracker()
-        {
-            if (IsEnabled.GetValueOrDefault() && !_isRegistered)
-            {
-                _event.AddClassHandler(typeof(object), HandleEvent, (RoutingStrategies)7, handledEventsToo: true);
-                _isRegistered = true;
-            }
-        }
-
-        private void HandleEvent(object sender, RoutedEventArgs e)
-        {
-            if (!_isRegistered || IsEnabled == false)
-                return;
-            if (sender is IVisual v && DevTools.BelongsToDevTool(v))
-                return;
-
-            var s = sender;
-            var handled = e.Handled;
-            var route = e.Route;
-
-            Action handler = delegate
-            {
-                if (_currentEvent == null || !_currentEvent.IsPartOfSameEventChain(e))
-                {
-                    _currentEvent = new FiredEvent(e, new ChainLink(s, handled, route));
-
-                    _parentViewModel.RecordedEvents.Add(_currentEvent);
-
-                    while (_parentViewModel.RecordedEvents.Count > 100)
-                        _parentViewModel.RecordedEvents.RemoveAt(0);
-                }
-                else
-                {
-                    _currentEvent.AddToChain(new ChainLink(s, handled, route));
-                }
-            };
-
-            if (!Dispatcher.UIThread.CheckAccess())
-                Dispatcher.UIThread.Post(handler);
-            else
-                handler();
-        }
-    }
-}

src/Avalonia.Diagnostics/ViewModels/ControlTreeNode.cs → src/Avalonia.Diagnostics/ViewModels/EventOwnerTreeNode.cs

@@ -11,16 +11,9 @@ using Avalonia.Interactivity;
 
 namespace Avalonia.Diagnostics.ViewModels
 {
-    internal class ControlTreeNode : EventTreeNode
+    internal class EventOwnerTreeNode : EventTreeNodeBase
     {
-        public ControlTreeNode(Type type, IEnumerable<RoutedEvent> events, EventsViewModel vm)
-            : base(null, type.Name)
-        {
-            this.Children = new AvaloniaList<EventTreeNode>(events.OrderBy(e => e.Name).Select(e => new EventEntryTreeNode(this, e, vm) { IsEnabled = IsDefault(e) }));
-            this.IsExpanded = true;
-        }
-
-        RoutedEvent[] defaultEvents = new RoutedEvent[]
+        private static readonly RoutedEvent[] s_defaultEvents = new RoutedEvent[]
         {
            Button.ClickEvent,
            InputElement.KeyDownEvent,
@@ -30,9 +23,12 @@ namespace Avalonia.Diagnostics.ViewModels
            InputElement.PointerPressedEvent,
         };
 
-        private bool IsDefault(RoutedEvent e)
+        public EventOwnerTreeNode(Type type, IEnumerable<RoutedEvent> events, EventsViewModel vm)
+            : base(null, type.Name)
         {
-            return defaultEvents.Contains(e);
+            this.Children = new AvaloniaList<EventTreeNodeBase>(events.OrderBy(e => e.Name)
+                .Select(e => new EventTreeNode(this, e, vm) { IsEnabled = s_defaultEvents.Contains(e) }));
+            this.IsExpanded = true;
         }
 
         public override bool? IsEnabled

src/Avalonia.Diagnostics/ViewModels/EventTreeNode.cs

@@ -1,80 +1,98 @@
 // 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.Diagnostics;
-using Avalonia.Collections;
+using System;
+
+using Avalonia.Diagnostics.Models;
+using Avalonia.Interactivity;
+using Avalonia.Threading;
 using Avalonia.VisualTree;
 
 namespace Avalonia.Diagnostics.ViewModels
 {
-    internal abstract class EventTreeNode : ViewModelBase
+    internal class EventTreeNode : EventTreeNodeBase
     {
-        internal bool _updateChildren = true;
-        internal bool _updateParent = true;
-        private bool _isExpanded;
-        private bool? _isEnabled = false;
-
-        public EventTreeNode(EventTreeNode parent, string text)
-        {
-            this.Parent = parent;
-            this.Text = text;
-        }
+        private RoutedEvent _event;
+        private EventsViewModel _parentViewModel;
+        private bool _isRegistered;
+        private FiredEvent _currentEvent;
 
-        public IAvaloniaReadOnlyList<EventTreeNode> Children
+        public EventTreeNode(EventOwnerTreeNode parent, RoutedEvent @event, EventsViewModel vm)
+            : base(parent, @event.Name)
         {
-            get;
-            protected set;
-        }
+            Contract.Requires<ArgumentNullException>(@event != null);
+            Contract.Requires<ArgumentNullException>(vm != null);
 
-        public bool IsExpanded
-        {
-            get { return _isExpanded; }
-            set { RaiseAndSetIfChanged(ref _isExpanded, value); }
+            this._event = @event;
+            this._parentViewModel = vm;
         }
 
-        public virtual bool? IsEnabled
+        public override bool? IsEnabled
         {
-            get { return _isEnabled; }
-            set { RaiseAndSetIfChanged(ref _isEnabled, value); }
+            get => base.IsEnabled;
+            set
+            {
+                if (base.IsEnabled != value)
+                {
+                    base.IsEnabled = value;
+                    UpdateTracker();
+                    if (Parent != null && _updateParent)
+                    {
+                        try
+                        {
+                            Parent._updateChildren = false;
+                            Parent.UpdateChecked();
+                        }
+                        finally
+                        {
+                            Parent._updateChildren = true;
+                        }
+                    }
+                }
+            }
         }
 
-        public EventTreeNode Parent
+        private void UpdateTracker()
         {
-            get;
+            if (IsEnabled.GetValueOrDefault() && !_isRegistered)
+            {
+                _event.AddClassHandler(typeof(object), HandleEvent, (RoutingStrategies)7, handledEventsToo: true);
+                _isRegistered = true;
+            }
         }
 
-        public string Text
+        private void HandleEvent(object sender, RoutedEventArgs e)
         {
-            get;
-            private set;
-        }
+            if (!_isRegistered || IsEnabled == false)
+                return;
+            if (sender is IVisual v && DevTools.BelongsToDevTool(v))
+                return;
 
-        internal void UpdateChecked()
-        {
-            IsEnabled = GetValue();
+            var s = sender;
+            var handled = e.Handled;
+            var route = e.Route;
 
-            bool? GetValue()
+            Action handler = delegate
             {
-                if (Children == null)
-                    return false;
-                bool? value = false;
-                for (int i = 0; i < Children.Count; i++)
+                if (_currentEvent == null || !_currentEvent.IsPartOfSameEventChain(e))
                 {
-                    if (i == 0)
-                    {
-                        value = Children[i].IsEnabled;
-                        continue;
-                    }
+                    _currentEvent = new FiredEvent(e, new EventChainLink(s, handled, route));
 
-                    if (value != Children[i].IsEnabled)
-                    {
-                        value = null;
-                        break;
-                    }
+                    _parentViewModel.RecordedEvents.Add(_currentEvent);
+
+                    while (_parentViewModel.RecordedEvents.Count > 100)
+                        _parentViewModel.RecordedEvents.RemoveAt(0);
                 }
+                else
+                {
+                    _currentEvent.AddToChain(new EventChainLink(s, handled, route));
+                }
+            };
 
-                return value;
-            }
+            if (!Dispatcher.UIThread.CheckAccess())
+                Dispatcher.UIThread.Post(handler);
+            else
+                handler();
         }
     }
 }

src/Avalonia.Diagnostics/ViewModels/EventTreeNodeBase.cs

@@ -0,0 +1,78 @@
+// 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 Avalonia.Collections;
+
+namespace Avalonia.Diagnostics.ViewModels
+{
+    internal abstract class EventTreeNodeBase : ViewModelBase
+    {
+        internal bool _updateChildren = true;
+        internal bool _updateParent = true;
+        private bool _isExpanded;
+        private bool? _isEnabled = false;
+
+        public EventTreeNodeBase(EventTreeNodeBase parent, string text)
+        {
+            this.Parent = parent;
+            this.Text = text;
+        }
+
+        public IAvaloniaReadOnlyList<EventTreeNodeBase> Children
+        {
+            get;
+            protected set;
+        }
+
+        public bool IsExpanded
+        {
+            get { return _isExpanded; }
+            set { RaiseAndSetIfChanged(ref _isExpanded, value); }
+        }
+
+        public virtual bool? IsEnabled
+        {
+            get { return _isEnabled; }
+            set { RaiseAndSetIfChanged(ref _isEnabled, value); }
+        }
+
+        public EventTreeNodeBase Parent
+        {
+            get;
+        }
+
+        public string Text
+        {
+            get;
+            private set;
+        }
+
+        internal void UpdateChecked()
+        {
+            IsEnabled = GetValue();
+
+            bool? GetValue()
+            {
+                if (Children == null)
+                    return false;
+                bool? value = false;
+                for (int i = 0; i < Children.Count; i++)
+                {
+                    if (i == 0)
+                    {
+                        value = Children[i].IsEnabled;
+                        continue;
+                    }
+
+                    if (value != Children[i].IsEnabled)
+                    {
+                        value = null;
+                        break;
+                    }
+                }
+
+                return value;
+            }
+        }
+    }
+}

src/Avalonia.Diagnostics/ViewModels/EventsViewModel.cs

@@ -2,26 +2,22 @@
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
 using System;
-using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Globalization;
 using System.Linq;
-using System.Text;
 using System.Windows.Input;
-using Avalonia.Collections;
+
 using Avalonia.Controls;
 using Avalonia.Data.Converters;
 using Avalonia.Interactivity;
 using Avalonia.Media;
-using Avalonia.Threading;
 
 namespace Avalonia.Diagnostics.ViewModels
 {
     internal class EventsViewModel : ViewModelBase
     {
-        private IControl _root;
+        private readonly IControl _root;
         private FiredEvent _selectedEvent;
-        private ICommand ClearCommand { get; }
 
         public EventsViewModel(IControl root)
         {
@@ -29,27 +25,11 @@ namespace Avalonia.Diagnostics.ViewModels
             this.Nodes = RoutedEventRegistry.Instance.GetAllRegistered()
                 .GroupBy(e => e.OwnerType)
                 .OrderBy(e => e.Key.Name)
-                .Select(g => new ControlTreeNode(g.Key, g, this))
+                .Select(g => new EventOwnerTreeNode(g.Key, g, this))
                 .ToArray();
         }
 
-        private void ClearExecute()
-        {
-            Action action = delegate
-            {
-                RecordedEvents.Clear();
-            };
-            if (!Dispatcher.UIThread.CheckAccess())
-            {
-                Dispatcher.UIThread.Post(action);
-            }
-            else
-            {
-                action();
-            }
-        }
-
-        public EventTreeNode[] Nodes { get; }
+        public EventTreeNodeBase[] Nodes { get; }
 
         public ObservableCollection<FiredEvent> RecordedEvents { get; } = new ObservableCollection<FiredEvent>();
 
@@ -58,6 +38,11 @@ namespace Avalonia.Diagnostics.ViewModels
             get => _selectedEvent;
             set => RaiseAndSetIfChanged(ref _selectedEvent, value);
         }
+
+        private void Clear()
+        {
+            RecordedEvents.Clear();
+        }
     }
 
     internal class BoolToBrushConverter : IValueConverter

src/Avalonia.Diagnostics/ViewModels/FiredEvent.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.ObjectModel;
+
 using Avalonia.Diagnostics.Models;
 using Avalonia.Interactivity;
 
@@ -11,17 +12,15 @@ namespace Avalonia.Diagnostics.ViewModels
     internal class FiredEvent : ViewModelBase
     {
         private RoutedEventArgs _eventArgs;
+        private EventChainLink _handledBy;
 
-        private ChainLink _handledBy;
-        private ChainLink _originator;
-
-        public FiredEvent(RoutedEventArgs eventArgs, ChainLink originator)
+        public FiredEvent(RoutedEventArgs eventArgs, EventChainLink originator)
         {
             Contract.Requires<ArgumentNullException>(eventArgs != null);
             Contract.Requires<ArgumentNullException>(originator != null);
 
             this._eventArgs = eventArgs;
-            this._originator = originator;
+            this.Originator = originator;
             AddToChain(originator);
         }
 
@@ -34,7 +33,7 @@ namespace Avalonia.Diagnostics.ViewModels
 
         public bool IsHandled => HandledBy?.Handled == true;
 
-        public ObservableCollection<ChainLink> EventChain { get; } = new ObservableCollection<ChainLink>();
+        public ObservableCollection<EventChainLink> EventChain { get; } = new ObservableCollection<EventChainLink>();
 
         public string DisplayText
         {
@@ -49,21 +48,9 @@ namespace Avalonia.Diagnostics.ViewModels
             }
         }
 
-        public ChainLink Originator
-        {
-            get { return _originator; }
-            set
-            {
-                if (_originator != value)
-                {
-                    _originator = value;
-                    RaisePropertyChanged();
-                    RaisePropertyChanged(nameof(DisplayText));
-                }
-            }
-        }
+        public EventChainLink Originator { get; }
 
-        public ChainLink HandledBy
+        public EventChainLink HandledBy
         {
             get { return _handledBy; }
             set
@@ -80,10 +67,10 @@ namespace Avalonia.Diagnostics.ViewModels
 
         public void AddToChain(object handler, bool handled, RoutingStrategies route)
         {
-            AddToChain(new ChainLink(handler, handled, route));
+            AddToChain(new EventChainLink(handler, handled, route));
         }
 
-        public void AddToChain(ChainLink link)
+        public void AddToChain(EventChainLink link)
         {
             EventChain.Add(link);
             if (HandledBy == null && link.Handled)

src/Avalonia.Diagnostics/Views/EventsView.xaml

@@ -7,7 +7,7 @@
     <Grid ColumnDefinitions="*,4,3*">
         <TreeView Name="tree" Items="{Binding Nodes}" SelectedItem="{Binding SelectedNode, Mode=TwoWay}" Grid.RowSpan="2">
             <TreeView.DataTemplates>
-                <TreeDataTemplate DataType="vm:EventTreeNode"
+                <TreeDataTemplate DataType="vm:EventTreeNodeBase"
                                   ItemsSource="{Binding Children}">
                     <CheckBox Content="{Binding Text}" IsChecked="{Binding IsEnabled, Mode=TwoWay}" />
                 </TreeDataTemplate>
@@ -46,7 +46,7 @@
                 </ListBox>
             </DockPanel>
             <StackPanel Orientation="Horizontal" Grid.Row="3">
-                <Button Content="Clear" Margin="3" Command="{Binding ClearExecute}"  />
+                <Button Content="Clear" Margin="3" Command="{Binding Clear}"  />
             </StackPanel>
         </Grid>
     </Grid>

src/Avalonia.Diagnostics/Views/EventsView.xaml.cs

@@ -1,4 +1,8 @@
-using System.Linq;
+// 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.Linq;
+
 using Avalonia.Controls;
 using Avalonia.Diagnostics.ViewModels;
 using Avalonia.Markup.Xaml;
@@ -7,7 +11,7 @@ namespace Avalonia.Diagnostics.Views
 {
     public class EventsView : UserControl
     {
-        ListBox _events;
+        private ListBox _events;
 
         public EventsView()
         {