Merge branch 'master' into fixes/project-status-wording

samples/ControlCatalog/ViewModels/MenuPageViewModel.cs

@@ -1,5 +1,6 @@
 using System.Collections.Generic;
 using System.Reactive;
+using System.Reactive.Linq;
 using System.Threading.Tasks;
 using Avalonia.Controls;
 using ReactiveUI;
@@ -11,7 +12,7 @@ namespace ControlCatalog.ViewModels
         public MenuPageViewModel()
         {
             OpenCommand = ReactiveCommand.CreateFromTask(Open);
-            SaveCommand = ReactiveCommand.Create(Save);
+            SaveCommand = ReactiveCommand.Create(Save, Observable.Return(false));
             OpenRecentCommand = ReactiveCommand.Create<string>(OpenRecent);
 
             MenuItems = new[]

src/Avalonia.Controls/Button.cs

@@ -33,8 +33,6 @@ namespace Avalonia.Controls
     /// </summary>
     public class Button : ContentControl
     {
-        private ICommand _command;
-
         /// <summary>
         /// Defines the <see cref="ClickMode"/> property.
         /// </summary>
@@ -75,6 +73,9 @@ namespace Avalonia.Controls
         public static readonly StyledProperty<bool> IsPressedProperty =
             AvaloniaProperty.Register<Button, bool>(nameof(IsPressed));
 
+        private ICommand _command;
+        private bool _commandCanExecute = true;
+
         /// <summary>
         /// Initializes static members of the <see cref="Button"/> class.
         /// </summary>
@@ -147,6 +148,8 @@ namespace Avalonia.Controls
             private set { SetValue(IsPressedProperty, value); }
         }
 
+        protected override bool IsEnabledCore => base.IsEnabledCore && _commandCanExecute; 
+
         /// <inheritdoc/>
         protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
         {
@@ -292,7 +295,11 @@ namespace Avalonia.Controls
             {
                 if (status?.ErrorType == BindingErrorType.Error)
                 {
-                    IsEnabled = false;
+                    if (_commandCanExecute)
+                    {
+                        _commandCanExecute = false;
+                        UpdateIsEffectivelyEnabled();
+                    }
                 }
             }
         }
@@ -351,9 +358,13 @@ namespace Avalonia.Controls
         /// <param name="e">The event args.</param>
         private void CanExecuteChanged(object sender, EventArgs e)
         {
-            // HACK: Just set the IsEnabled property for the moment. This needs to be changed to
+            var canExecute = Command == null || Command.CanExecute(CommandParameter);
-            // use IsEnabledCore etc. but it will do for now.
+
-            IsEnabled = Command == null || Command.CanExecute(CommandParameter);
+            if (canExecute != _commandCanExecute)
+            {
+                _commandCanExecute = canExecute;
+                UpdateIsEffectivelyEnabled();
+            }
         }
 
         /// <summary>

src/Avalonia.Controls/ComboBox.cs

@@ -302,7 +302,7 @@ namespace Avalonia.Controls
             }
         }
 
-        private bool CanFocus(IControl control) => control.Focusable && control.IsEnabledCore && control.IsVisible;
+        private bool CanFocus(IControl control) => control.Focusable && control.IsEffectivelyEnabled && control.IsVisible;
 
         private void UpdateSelectionBoxItem(object item)
         {

src/Avalonia.Controls/MenuItem.cs

@@ -9,6 +9,7 @@ using Avalonia.Controls.Generators;
 using Avalonia.Controls.Mixins;
 using Avalonia.Controls.Primitives;
 using Avalonia.Controls.Templates;
+using Avalonia.Data;
 using Avalonia.Input;
 using Avalonia.Interactivity;
 using Avalonia.LogicalTree;
@@ -20,8 +21,6 @@ namespace Avalonia.Controls
     /// </summary>
     public class MenuItem : HeaderedSelectingItemsControl, IMenuItem, ISelectable
     {
-        private ICommand _command;
-
         /// <summary>
         /// Defines the <see cref="Command"/> property.
         /// </summary>
@@ -91,9 +90,8 @@ namespace Avalonia.Controls
         private static readonly ITemplate<IPanel> DefaultPanel =
             new FuncTemplate<IPanel>(() => new StackPanel());
 
-        /// <summary>
+        private ICommand _command;
-        /// The submenu popup.
+        private bool _commandCanExecute = true;
-        /// </summary>
         private Popup _popup;
 
         /// <summary>
@@ -231,6 +229,8 @@ namespace Avalonia.Controls
         /// <inheritdoc/>
         IMenuElement IMenuItem.Parent => Parent as IMenuElement;
 
+        protected override bool IsEnabledCore => base.IsEnabledCore && _commandCanExecute;
+
         /// <inheritdoc/>
         bool IMenuElement.MoveSelection(NavigationDirection direction, bool wrap) => MoveSelection(direction, wrap);
 
@@ -394,6 +394,22 @@ namespace Avalonia.Controls
             }
         }
 
+        protected override void UpdateDataValidation(AvaloniaProperty property, BindingNotification status)
+        {
+            base.UpdateDataValidation(property, status);
+            if (property == CommandProperty)
+            {
+                if (status?.ErrorType == BindingErrorType.Error)
+                {
+                    if (_commandCanExecute)
+                    {
+                        _commandCanExecute = false;
+                        UpdateIsEffectivelyEnabled();
+                    }
+                }
+            }
+        }
+
         /// <summary>
         /// Closes all submenus of the menu item.
         /// </summary>
@@ -437,9 +453,13 @@ namespace Avalonia.Controls
         /// <param name="e">The event args.</param>
         private void CanExecuteChanged(object sender, EventArgs e)
         {
-            // HACK: Just set the IsEnabled property for the moment. This needs to be changed to
+            var canExecute = Command == null || Command.CanExecute(CommandParameter);
-            // use IsEnabledCore etc. but it will do for now.
+
-            IsEnabled = Command == null || Command.CanExecute(CommandParameter);
+            if (canExecute != _commandCanExecute)
+            {
+                _commandCanExecute = canExecute;
+                UpdateIsEffectivelyEnabled();
+            }
         }
 
         /// <summary>

src/Avalonia.Diagnostics/ViewModels/EventTreeNode.cs

@@ -56,6 +56,7 @@ namespace Avalonia.Diagnostics.ViewModels
         {
             if (IsEnabled.GetValueOrDefault() && !_isRegistered)
             {
+                // FIXME: This leaks event handlers.
                 _event.AddClassHandler(typeof(object), HandleEvent, (RoutingStrategies)7, handledEventsToo: true);
                 _isRegistered = true;
             }

src/Avalonia.Input/FocusManager.cs

@@ -23,7 +23,7 @@ namespace Avalonia.Input
         /// <summary>
         /// Initializes a new instance of the <see cref="FocusManager"/> class.
         /// </summary>
-        public FocusManager()
+        static FocusManager()
         {
             InputElement.PointerPressedEvent.AddClassHandler(
                 typeof(IInputElement),
@@ -146,7 +146,7 @@ namespace Avalonia.Input
         /// </summary>
         /// <param name="e">The element.</param>
         /// <returns>True if the element can be focused.</returns>
-        private static bool CanFocus(IInputElement e) => e.Focusable && e.IsEnabledCore && e.IsVisible;
+        private static bool CanFocus(IInputElement e) => e.Focusable && e.IsEffectivelyEnabled && e.IsVisible;
 
         /// <summary>
         /// Gets the focus scope ancestors of the specified control, traversing popups.
@@ -174,7 +174,7 @@ namespace Avalonia.Input
         /// </summary>
         /// <param name="sender">The event sender.</param>
         /// <param name="e">The event args.</param>
-        private void OnPreviewPointerPressed(object sender, RoutedEventArgs e)
+        private static void OnPreviewPointerPressed(object sender, RoutedEventArgs e)
         {
             var ev = (PointerPressedEventArgs)e;
 
@@ -191,7 +191,7 @@ namespace Avalonia.Input
 
                 if (element != null)
                 {
-                    Focus(element, NavigationMethod.Pointer, ev.InputModifiers);
+                    Instance?.Focus(element, NavigationMethod.Pointer, ev.InputModifiers);
                 }
             }
         }

src/Avalonia.Input/IInputElement.cs

@@ -83,14 +83,14 @@ namespace Avalonia.Input
         Cursor Cursor { get; }
 
         /// <summary>
-        /// Gets a value indicating whether the control is effectively enabled for user interaction.
+        /// Gets a value indicating whether this control and all its parents are enabled.
         /// </summary>
         /// <remarks>
         /// The <see cref="IsEnabled"/> property is used to toggle the enabled state for individual
-        /// controls. The <see cref="IsEnabledCore"/> property takes into account the
+        /// controls. The <see cref="IsEffectivelyEnabled"/> property takes into account the
         /// <see cref="IsEnabled"/> value of this control and its parent controls.
         /// </remarks>
-        bool IsEnabledCore { get; }
+        bool IsEffectivelyEnabled { get; }
 
         /// <summary>
         /// Gets a value indicating whether the control is focused.

src/Avalonia.Input/InputElement.cs

@@ -28,10 +28,12 @@ namespace Avalonia.Input
             AvaloniaProperty.Register<InputElement, bool>(nameof(IsEnabled), true);
 
         /// <summary>
-        /// Defines the <see cref="IsEnabledCore"/> property.
+        /// Defines the <see cref="IsEffectivelyEnabled"/> property.
         /// </summary>
-        public static readonly StyledProperty<bool> IsEnabledCoreProperty =
+        public static readonly DirectProperty<InputElement, bool> IsEffectivelyEnabledProperty =
-            AvaloniaProperty.Register<InputElement, bool>(nameof(IsEnabledCore), true);
+            AvaloniaProperty.RegisterDirect<InputElement, bool>(
+                nameof(IsEffectivelyEnabled),
+                o => o.IsEffectivelyEnabled);
 
         /// <summary>
         /// Gets or sets associated mouse cursor.
@@ -155,6 +157,7 @@ namespace Avalonia.Input
         /// </summary>
         public static readonly RoutedEvent<RoutedEventArgs> DoubleTappedEvent = Gestures.DoubleTappedEvent;
 
+        private bool _isEffectivelyEnabled = true;
         private bool _isFocused;
         private bool _isPointerOver;
         private GestureRecognizerCollection _gestureRecognizers;
@@ -179,7 +182,7 @@ namespace Avalonia.Input
             PointerCaptureLostEvent.AddClassHandler<InputElement>(x => x.OnPointerCaptureLost);
             PointerWheelChangedEvent.AddClassHandler<InputElement>(x => x.OnPointerWheelChanged);
 
-            PseudoClass<InputElement, bool>(IsEnabledCoreProperty, x => !x, ":disabled");
+            PseudoClass<InputElement, bool>(IsEffectivelyEnabledProperty, x => !x, ":disabled");
             PseudoClass<InputElement>(IsFocusedProperty, ":focus");
             PseudoClass<InputElement>(IsPointerOverProperty, ":pointerover");
         }
@@ -365,31 +368,25 @@ namespace Avalonia.Input
             internal set { SetAndRaise(IsPointerOverProperty, ref _isPointerOver, value); }
         }
 
-        /// <summary>
+        /// <inheritdoc/>
-        /// Gets a value indicating whether the control is effectively enabled for user interaction.
+        public bool IsEffectivelyEnabled
-        /// </summary>
+        {
-        /// <remarks>
+            get => _isEffectivelyEnabled;
-        /// The <see cref="IsEnabled"/> property is used to toggle the enabled state for individual
+            private set => SetAndRaise(IsEffectivelyEnabledProperty, ref _isEffectivelyEnabled, value);
-        /// controls. The <see cref="IsEnabledCore"/> property takes into account the
+        }
-        /// <see cref="IsEnabled"/> value of this control and its parent controls.
+
-        /// </remarks>
+        public List<KeyBinding> KeyBindings { get; } = new List<KeyBinding>();
-        bool IInputElement.IsEnabledCore => IsEnabledCore;
 
         /// <summary>
-        /// Gets a value indicating whether the control is effectively enabled for user interaction.
+        /// Allows a derived class to override the enabled state of the control.
         /// </summary>
         /// <remarks>
-        /// The <see cref="IsEnabled"/> property is used to toggle the enabled state for individual
+        /// Derived controls may wish to disable the enabled state of the control without overwriting the
-        /// controls. The <see cref="IsEnabledCore"/> property takes into account the
+        /// user-supplied <see cref="IsEnabled"/> setting. This can be done by overriding this property
-        /// <see cref="IsEnabled"/> value of this control and its parent controls.
+        /// to return the overridden enabled state. If the value returned from <see cref="IsEnabledCore"/>
+        /// should change, then the derived control should call <see cref="UpdateIsEffectivelyEnabled()"/>.
         /// </remarks>
-        protected bool IsEnabledCore
+        protected virtual bool IsEnabledCore => IsEnabled;
-        {
-            get { return GetValue(IsEnabledCoreProperty); }
-            set { SetValue(IsEnabledCoreProperty, value); }
-        }
-
-        public List<KeyBinding> KeyBindings { get; } = new List<KeyBinding>();
 
         public GestureRecognizerCollection GestureRecognizers
             => _gestureRecognizers ?? (_gestureRecognizers = new GestureRecognizerCollection(this));
@@ -417,7 +414,7 @@ namespace Avalonia.Input
         protected override void OnAttachedToVisualTreeCore(VisualTreeAttachmentEventArgs e)
         {
             base.OnAttachedToVisualTreeCore(e);
-            UpdateIsEnabledCore();
+            UpdateIsEffectivelyEnabled();
         }
 
         /// <summary>
@@ -525,9 +522,18 @@ namespace Avalonia.Input
         {
         }
 
+        /// <summary>
+        /// Updates the <see cref="IsEffectivelyEnabled"/> property value according to the parent
+        /// control's enabled state and <see cref="IsEnabledCore"/>.
+        /// </summary>
+        protected void UpdateIsEffectivelyEnabled()
+        {
+            UpdateIsEffectivelyEnabled(this.GetVisualParent<InputElement>());
+        }
+
         private static void IsEnabledChanged(AvaloniaPropertyChangedEventArgs e)
         {
-            ((InputElement)e.Sender).UpdateIsEnabledCore();
+            ((InputElement)e.Sender).UpdateIsEffectivelyEnabled();
         }
 
         /// <summary>
@@ -551,32 +557,17 @@ namespace Avalonia.Input
         }
 
         /// <summary>
-        /// Updates the <see cref="IsEnabledCore"/> property value.
+        /// Updates the <see cref="IsEffectivelyEnabled"/> property based on the parent's
-        /// </summary>
+        /// <see cref="IsEffectivelyEnabled"/>.
-        private void UpdateIsEnabledCore()
-        {
-            UpdateIsEnabledCore(this.GetVisualParent<InputElement>());
-        }
-
-        /// <summary>
-        /// Updates the <see cref="IsEnabledCore"/> property based on the parent's
-        /// <see cref="IsEnabledCore"/>.
         /// </summary>
         /// <param name="parent">The parent control.</param>
-        private void UpdateIsEnabledCore(InputElement parent)
+        private void UpdateIsEffectivelyEnabled(InputElement parent)
         {
-            if (parent != null)
+            IsEffectivelyEnabled = IsEnabledCore && (parent?.IsEffectivelyEnabled ?? true);
-            {
-                IsEnabledCore = IsEnabled && parent.IsEnabledCore;
-            }
-            else
-            {
-                IsEnabledCore = IsEnabled;
-            }
 
             foreach (var child in this.GetVisualChildren().OfType<InputElement>())
             {
-                child.UpdateIsEnabledCore(this);
+                child.UpdateIsEffectivelyEnabled(this);
             }
         }
     }

src/Avalonia.Input/InputExtensions.cs

@@ -45,7 +45,7 @@ namespace Avalonia.Input
             return element != null &&
                    element.IsVisible &&
                    element.IsHitTestVisible &&
-                   element.IsEnabledCore &&
+                   element.IsEffectivelyEnabled &&
                    element.IsAttachedToVisualTree;
         }
     }

src/Avalonia.Input/Navigation/FocusExtensions.cs

@@ -13,13 +13,13 @@ namespace Avalonia.Input.Navigation
         /// </summary>
         /// <param name="e">The element.</param>
         /// <returns>True if the element can be focused.</returns>
-        public static bool CanFocus(this IInputElement e) => e.Focusable && e.IsEnabledCore && e.IsVisible;
+        public static bool CanFocus(this IInputElement e) => e.Focusable && e.IsEffectivelyEnabled && e.IsVisible;
 
         /// <summary>
         /// Checks if descendants of the specified element can be focused.
         /// </summary>
         /// <param name="e">The element.</param>
         /// <returns>True if descendants of the element can be focused.</returns>
-        public static bool CanFocusDescendants(this IInputElement e) => e.IsEnabledCore && e.IsVisible;
+        public static bool CanFocusDescendants(this IInputElement e) => e.IsEffectivelyEnabled && e.IsVisible;
     }
 }

tests/Avalonia.Controls.UnitTests/ButtonTests.cs

@@ -26,11 +26,26 @@ namespace Avalonia.Controls.UnitTests
             };
             var root = new TestRoot { Child = target };
 
-            Assert.False(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
             command.IsEnabled = true;
-            Assert.True(target.IsEnabled);
+            Assert.True(target.IsEffectivelyEnabled);
             command.IsEnabled = false;
-            Assert.False(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
+        }
+
+        [Fact]
+        public void Button_Is_Disabled_When_Command_Is_Enabled_But_IsEnabled_Is_False()
+        {
+            var command = new TestCommand(true);
+            var target = new Button
+            {
+                IsEnabled = false,
+                Command = command,
+            };
+
+            var root = new TestRoot { Child = target };
+
+            Assert.False(((IInputElement)target).IsEffectivelyEnabled);
         }
 
         [Fact]
@@ -41,7 +56,8 @@ namespace Avalonia.Controls.UnitTests
                 [!Button.CommandProperty] = new Binding("Command"),
             };
 
-            Assert.False(target.IsEnabled);
+            Assert.True(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
         }
 
         [Fact]
@@ -59,8 +75,12 @@ namespace Avalonia.Controls.UnitTests
             };
 
             Assert.True(target.IsEnabled);
+            Assert.True(target.IsEffectivelyEnabled);
+
             target.DataContext = null;
-            Assert.False(target.IsEnabled);
+
+            Assert.True(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
         }
 
         [Fact]
@@ -77,9 +97,13 @@ namespace Avalonia.Controls.UnitTests
                 [!Button.CommandProperty] = new Binding("Command"),
             };
 
-            Assert.False(target.IsEnabled);
+            Assert.True(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
+
             target.DataContext = viewModel;
+
             Assert.True(target.IsEnabled);
+            Assert.True(target.IsEffectivelyEnabled);
         }
 
         [Fact]
@@ -96,9 +120,13 @@ namespace Avalonia.Controls.UnitTests
                 [!Button.CommandProperty] = new Binding("Command"),
             };
 
-            Assert.False(target.IsEnabled);
+            Assert.True(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
+
             target.DataContext = viewModel;
-            Assert.False(target.IsEnabled);
+
+            Assert.True(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
         }
 
         [Fact]

tests/Avalonia.Controls.UnitTests/MenuItemTests.cs

@@ -2,6 +2,8 @@
 using System.Collections.Generic;
 using System.Text;
 using System.Windows.Input;
+using Avalonia.Data;
+using Avalonia.Input;
 using Avalonia.UnitTests;
 using Xunit;
 
@@ -25,6 +27,103 @@ namespace Avalonia.Controls.UnitTests
             Assert.False(target.Focusable);
         }
 
+
+        [Fact]
+        public void MenuItem_Is_Disabled_When_Command_Is_Enabled_But_IsEnabled_Is_False()
+        {
+            var command = new TestCommand(true);
+            var target = new MenuItem
+            {
+                IsEnabled = false,
+                Command = command,
+            };
+
+            var root = new TestRoot { Child = target };
+
+            Assert.False(((IInputElement)target).IsEffectivelyEnabled);
+        }
+
+        [Fact]
+        public void MenuItem_Is_Disabled_When_Bound_Command_Doesnt_Exist()
+        {
+            var target = new MenuItem
+            {
+                [!MenuItem.CommandProperty] = new Binding("Command"),
+            };
+
+            Assert.True(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
+        }
+
+        [Fact]
+        public void MenuItem_Is_Disabled_When_Bound_Command_Is_Removed()
+        {
+            var viewModel = new
+            {
+                Command = new TestCommand(true),
+            };
+
+            var target = new MenuItem
+            {
+                DataContext = viewModel,
+                [!MenuItem.CommandProperty] = new Binding("Command"),
+            };
+
+            Assert.True(target.IsEnabled);
+            Assert.True(target.IsEffectivelyEnabled);
+
+            target.DataContext = null;
+
+            Assert.True(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
+        }
+
+        [Fact]
+        public void MenuItem_Is_Enabled_When_Bound_Command_Is_Added()
+        {
+            var viewModel = new
+            {
+                Command = new TestCommand(true),
+            };
+
+            var target = new MenuItem
+            {
+                DataContext = new object(),
+                [!MenuItem.CommandProperty] = new Binding("Command"),
+            };
+
+            Assert.True(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
+
+            target.DataContext = viewModel;
+
+            Assert.True(target.IsEnabled);
+            Assert.True(target.IsEffectivelyEnabled);
+        }
+
+        [Fact]
+        public void MenuItem_Is_Disabled_When_Disabled_Bound_Command_Is_Added()
+        {
+            var viewModel = new
+            {
+                Command = new TestCommand(false),
+            };
+
+            var target = new MenuItem
+            {
+                DataContext = new object(),
+                [!MenuItem.CommandProperty] = new Binding("Command"),
+            };
+
+            Assert.True(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
+
+            target.DataContext = viewModel;
+
+            Assert.True(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
+        }
+
         [Fact]
         public void MenuItem_Does_Not_Subscribe_To_Command_CanExecuteChanged_Until_Added_To_Logical_Tree()
         {
@@ -60,8 +159,14 @@ namespace Avalonia.Controls.UnitTests
 
         private class TestCommand : ICommand
         {
+            private bool _enabled;
             private EventHandler _canExecuteChanged;
 
+            public TestCommand(bool enabled = true)
+            {
+                _enabled = enabled;
+            }
+
             public int SubscriptionCount { get; private set; }
 
             public event EventHandler CanExecuteChanged
@@ -70,7 +175,7 @@ namespace Avalonia.Controls.UnitTests
                 remove { _canExecuteChanged -= value; --SubscriptionCount; }
             }
 
-            public bool CanExecute(object parameter) => true;
+            public bool CanExecute(object parameter) => _enabled;
 
             public void Execute(object parameter)
             {

tests/Avalonia.Input.UnitTests/InputElement_Enabled.cs

@@ -0,0 +1,101 @@
+// 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.Controls;
+using Xunit;
+
+namespace Avalonia.Input.UnitTests
+{
+    public class InputElement_Enabled
+    {
+        [Fact]
+        public void IsEffectivelyEnabled_Follows_IsEnabled()
+        {
+            var target = new Decorator();
+
+            Assert.True(target.IsEnabled);
+            Assert.True(target.IsEffectivelyEnabled);
+
+            target.IsEnabled = false;
+
+            Assert.False(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
+        }
+
+        [Fact]
+        public void IsEffectivelyEnabled_Follows_Ancestor_IsEnabled()
+        {
+            Decorator child;
+            Decorator grandchild;
+            var target = new Decorator
+            {
+                Child = child = new Decorator
+                {
+                    Child = grandchild = new Decorator(),
+                }
+            };
+
+            Assert.True(target.IsEnabled);
+            Assert.True(target.IsEffectivelyEnabled);
+            Assert.True(child.IsEnabled);
+            Assert.True(child.IsEffectivelyEnabled);
+            Assert.True(grandchild.IsEnabled);
+            Assert.True(grandchild.IsEffectivelyEnabled);
+
+            target.IsEnabled = false;
+
+            Assert.False(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
+            Assert.True(child.IsEnabled);
+            Assert.False(child.IsEffectivelyEnabled);
+            Assert.True(grandchild.IsEnabled);
+            Assert.False(grandchild.IsEffectivelyEnabled);
+        }
+
+        [Fact]
+        public void Disabled_Pseudoclass_Follows_IsEffectivelyEnabled()
+        {
+            Decorator child;
+            var target = new Decorator
+            {
+                Child = child = new Decorator()
+            };
+
+            Assert.DoesNotContain(":disabled", child.Classes);
+
+            target.IsEnabled = false;
+
+            Assert.Contains(":disabled", child.Classes);
+        }
+
+        [Fact]
+        public void IsEffectivelyEnabled_Respects_IsEnabledCore()
+        {
+            Decorator child;
+            var target = new TestControl
+            {
+                Child = child = new Decorator()
+            };
+
+            target.ShouldEnable = false;
+
+            Assert.True(target.IsEnabled);
+            Assert.False(target.IsEffectivelyEnabled);
+            Assert.True(child.IsEnabled);
+            Assert.False(child.IsEffectivelyEnabled);
+        }
+
+        private class TestControl : Decorator
+        {
+            private bool _shouldEnable;
+
+            public bool ShouldEnable
+            {
+                get => _shouldEnable;
+                set { _shouldEnable = value; UpdateIsEffectivelyEnabled(); }
+            }
+
+            protected override bool IsEnabledCore => IsEnabled && _shouldEnable; 
+        }
+    }
+}