diff --git a/src/Avalonia.Controls/Notifications/WindowNotificationManager.cs b/src/Avalonia.Controls/Notifications/WindowNotificationManager.cs
index 1a9347e317..f27bb5fac6 100644
--- a/src/Avalonia.Controls/Notifications/WindowNotificationManager.cs
+++ b/src/Avalonia.Controls/Notifications/WindowNotificationManager.cs
@@ -7,6 +7,7 @@ using System.Linq;
 using System.Reactive.Linq;
 using System.Threading.Tasks;
 using Avalonia.Controls.Primitives;
+using Avalonia.Rendering;
 using Avalonia.VisualTree;
 
 namespace Avalonia.Controls.Notifications
@@ -14,7 +15,7 @@ namespace Avalonia.Controls.Notifications
     /// <summary>
     /// An <see cref="INotificationManager"/> that displays notifications in a <see cref="Window"/>.
     /// </summary>
-    public class WindowNotificationManager : TemplatedControl, IManagedNotificationManager
+    public class WindowNotificationManager : TemplatedControl, IManagedNotificationManager, ICustomSimpleHitTest
     {
         private IList _items;
 
@@ -153,5 +154,7 @@ namespace Avalonia.Controls.Notifications
 
             adornerLayer?.Children.Add(this);
         }
+
+        public bool HitTest(Point point) => VisualChildren.HitTestCustom(point);
     }
 }
diff --git a/src/Avalonia.Controls/Primitives/AdornerLayer.cs b/src/Avalonia.Controls/Primitives/AdornerLayer.cs
index ebe5e0a93e..9a2f0310d7 100644
--- a/src/Avalonia.Controls/Primitives/AdornerLayer.cs
+++ b/src/Avalonia.Controls/Primitives/AdornerLayer.cs
@@ -138,10 +138,7 @@ namespace Avalonia.Controls.Primitives
             }
         }
 
-        public bool HitTest(Point point)
-        {
-            return Children.Any(ctrl => ctrl.TransformedBounds?.Contains(point) == true);
-        }
+        public bool HitTest(Point point) => Children.HitTestCustom(point);
 
         private class AdornedElementInfo
         {
diff --git a/src/Avalonia.Controls/Primitives/OverlayLayer.cs b/src/Avalonia.Controls/Primitives/OverlayLayer.cs
index 487a5e91e4..5150033a53 100644
--- a/src/Avalonia.Controls/Primitives/OverlayLayer.cs
+++ b/src/Avalonia.Controls/Primitives/OverlayLayer.cs
@@ -21,11 +21,8 @@ namespace Avalonia.Controls.Primitives
 
             return null;
         }
-        
-        public bool HitTest(Point point)
-        {
-            return Children.Any(ctrl => ctrl.TransformedBounds?.Contains(point) == true);
-        }
+
+        public bool HitTest(Point point) => Children.HitTestCustom(point);
         
         protected override Size ArrangeOverride(Size finalSize)
         {
diff --git a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
index a5bbcec186..69da211aa4 100644
--- a/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
+++ b/src/Avalonia.Controls/Primitives/SelectingItemsControl.cs
@@ -5,6 +5,7 @@ using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Specialized;
+using System.Diagnostics;
 using System.Linq;
 using Avalonia.Collections;
 using Avalonia.Controls.Generators;
@@ -240,17 +241,14 @@ namespace Avalonia.Controls.Primitives
         public override void BeginInit()
         {
             base.BeginInit();
-            ++_updateCount;
-            _updateSelectedIndex = int.MinValue;
+
+            InternalBeginInit();
         }
 
         /// <inheritdoc/>
         public override void EndInit()
         {
-            if (--_updateCount == 0)
-            {
-                UpdateFinished();
-            }
+            InternalEndInit();
 
             base.EndInit();
         }
@@ -437,7 +435,8 @@ namespace Avalonia.Controls.Primitives
         protected override void OnDataContextBeginUpdate()
         {
             base.OnDataContextBeginUpdate();
-            ++_updateCount;
+
+            InternalBeginInit();
         }
 
         /// <inheritdoc/>
@@ -445,10 +444,7 @@ namespace Avalonia.Controls.Primitives
         {
             base.OnDataContextEndUpdate();
 
-            if (--_updateCount == 0)
-            {
-                UpdateFinished();
-            }
+            InternalEndInit();
         }
 
         protected override void OnKeyDown(KeyEventArgs e)
@@ -1118,6 +1114,26 @@ namespace Avalonia.Controls.Primitives
             }
         }
 
+        private void InternalBeginInit()
+        {
+            if (_updateCount == 0)
+            {
+                _updateSelectedIndex = int.MinValue;
+            }
+
+            ++_updateCount;
+        }
+
+        private void InternalEndInit()
+        {
+            Debug.Assert(_updateCount > 0);
+
+            if (--_updateCount == 0)
+            {
+                UpdateFinished();
+            }
+        }
+
         private class Selection : IEnumerable<int>
         {
             private readonly List<int> _list = new List<int>();
diff --git a/src/Avalonia.Controls/Primitives/ToggleButton.cs b/src/Avalonia.Controls/Primitives/ToggleButton.cs
index e7cd0697a0..4b3e8e2110 100644
--- a/src/Avalonia.Controls/Primitives/ToggleButton.cs
+++ b/src/Avalonia.Controls/Primitives/ToggleButton.cs
@@ -7,8 +7,14 @@ using Avalonia.Data;
 
 namespace Avalonia.Controls.Primitives
 {
+    /// <summary>
+    /// Represents a control that a user can select (check) or clear (uncheck). Base class for controls that can switch states.
+    /// </summary>
     public class ToggleButton : Button
     {
+        /// <summary>
+        /// Defines the <see cref="IsChecked"/> property.
+        /// </summary>
         public static readonly DirectProperty<ToggleButton, bool?> IsCheckedProperty =
             AvaloniaProperty.RegisterDirect<ToggleButton, bool?>(
                 nameof(IsChecked),
@@ -17,9 +23,30 @@ namespace Avalonia.Controls.Primitives
                 unsetValue: null,
                 defaultBindingMode: BindingMode.TwoWay);
 
+        /// <summary>
+        /// Defines the <see cref="IsThreeState"/> property.
+        /// </summary>
         public static readonly StyledProperty<bool> IsThreeStateProperty =
             AvaloniaProperty.Register<ToggleButton, bool>(nameof(IsThreeState));
 
+        /// <summary>
+        /// Defines the <see cref="Checked"/> event.
+        /// </summary>
+        public static readonly RoutedEvent<RoutedEventArgs> CheckedEvent =
+            RoutedEvent.Register<ToggleButton, RoutedEventArgs>(nameof(Checked), RoutingStrategies.Bubble);
+
+        /// <summary>
+        /// Defines the <see cref="Unchecked"/> event.
+        /// </summary>
+        public static readonly RoutedEvent<RoutedEventArgs> UncheckedEvent =
+            RoutedEvent.Register<ToggleButton, RoutedEventArgs>(nameof(Unchecked), RoutingStrategies.Bubble);
+
+        /// <summary>
+        /// Defines the <see cref="Unchecked"/> event.
+        /// </summary>
+        public static readonly RoutedEvent<RoutedEventArgs> IndeterminateEvent =
+            RoutedEvent.Register<ToggleButton, RoutedEventArgs>(nameof(Indeterminate), RoutingStrategies.Bubble);
+
         private bool? _isChecked = false;
 
         static ToggleButton()
@@ -27,14 +54,49 @@ namespace Avalonia.Controls.Primitives
             PseudoClass<ToggleButton, bool?>(IsCheckedProperty, c => c == true, ":checked");
             PseudoClass<ToggleButton, bool?>(IsCheckedProperty, c => c == false, ":unchecked");
             PseudoClass<ToggleButton, bool?>(IsCheckedProperty, c => c == null, ":indeterminate");
+
+            IsCheckedProperty.Changed.AddClassHandler<ToggleButton>((x, e) => x.OnIsCheckedChanged(e));
+        }
+
+        /// <summary>
+        /// Raised when a <see cref="ToggleButton"/> is checked.
+        /// </summary>
+        public event EventHandler<RoutedEventArgs> Checked
+        {
+            add => AddHandler(CheckedEvent, value);
+            remove => RemoveHandler(CheckedEvent, value);
+        }
+
+        /// <summary>
+        /// Raised when a <see cref="ToggleButton"/> is unchecked.
+        /// </summary>
+        public event EventHandler<RoutedEventArgs> Unchecked
+        {
+            add => AddHandler(UncheckedEvent, value);
+            remove => RemoveHandler(UncheckedEvent, value);
+        }
+
+        /// <summary>
+        /// Raised when a <see cref="ToggleButton"/> is neither checked nor unchecked.
+        /// </summary>
+        public event EventHandler<RoutedEventArgs> Indeterminate
+        {
+            add => AddHandler(IndeterminateEvent, value);
+            remove => RemoveHandler(IndeterminateEvent, value);
         }
 
+        /// <summary>
+        /// Gets or sets whether the <see cref="ToggleButton"/> is checked.
+        /// </summary>
         public bool? IsChecked
         {
-            get { return _isChecked; }
-            set { SetAndRaise(IsCheckedProperty, ref _isChecked, value); }
+            get => _isChecked;
+            set => SetAndRaise(IsCheckedProperty, ref _isChecked, value);
         }
 
+        /// <summary>
+        /// Gets or sets a value that indicates whether the control supports three states.
+        /// </summary>
         public bool IsThreeState
         {
             get => GetValue(IsThreeStateProperty);
@@ -47,18 +109,78 @@ namespace Avalonia.Controls.Primitives
             base.OnClick();
         }
 
+        /// <summary>
+        /// Toggles the <see cref="IsChecked"/> property.
+        /// </summary>
         protected virtual void Toggle()
         {
             if (IsChecked.HasValue)
+            {
                 if (IsChecked.Value)
+                {
                     if (IsThreeState)
+                    {
                         IsChecked = null;
+                    }
                     else
+                    {
                         IsChecked = false;
+                    }
+                }
                 else
+                {
                     IsChecked = true;
+                }
+            }
             else
+            {
                 IsChecked = false;
+            }
+        }
+
+        /// <summary>
+        /// Called when <see cref="IsChecked"/> becomes true.
+        /// </summary>
+        /// <param name="e">Event arguments for the routed event that is raised by the default implementation of this method.</param>
+        protected virtual void OnChecked(RoutedEventArgs e)
+        {
+            RaiseEvent(e);
+        }
+
+        /// <summary>
+        /// Called when <see cref="IsChecked"/> becomes false.
+        /// </summary>
+        /// <param name="e">Event arguments for the routed event that is raised by the default implementation of this method.</param>
+        protected virtual void OnUnchecked(RoutedEventArgs e)
+        {
+            RaiseEvent(e);
+        }
+
+        /// <summary>
+        /// Called when <see cref="IsChecked"/> becomes null.
+        /// </summary>
+        /// <param name="e">Event arguments for the routed event that is raised by the default implementation of this method.</param>
+        protected virtual void OnIndeterminate(RoutedEventArgs e)
+        {
+            RaiseEvent(e);
+        }
+
+        private void OnIsCheckedChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            var newValue = (bool?)e.NewValue;
+
+            switch (newValue)
+            {
+                case true:
+                    OnChecked(new RoutedEventArgs(CheckedEvent));
+                    break;
+                case false:
+                    OnUnchecked(new RoutedEventArgs(UncheckedEvent));
+                    break;
+                default:
+                    OnIndeterminate(new RoutedEventArgs(IndeterminateEvent));
+                    break;
+            }
         }
     }
 }
diff --git a/src/Avalonia.Visuals/Rendering/ICustomSimpleHitTest.cs b/src/Avalonia.Visuals/Rendering/ICustomSimpleHitTest.cs
index 7199053b08..4c15de0312 100644
--- a/src/Avalonia.Visuals/Rendering/ICustomSimpleHitTest.cs
+++ b/src/Avalonia.Visuals/Rendering/ICustomSimpleHitTest.cs
@@ -1,3 +1,7 @@
+using System.Collections.Generic;
+using System.Linq;
+using Avalonia.VisualTree;
+
 namespace Avalonia.Rendering
 {
     /// <summary>
@@ -9,4 +13,13 @@ namespace Avalonia.Rendering
     {
         bool HitTest(Point point);
     }
+
+    public static class CustomSimpleHitTestExtensions
+    {
+        public static bool HitTestCustom(this IVisual visual, Point point)
+            => (visual as ICustomSimpleHitTest)?.HitTest(point) ?? visual.TransformedBounds?.Contains(point) == true;
+
+        public static bool HitTestCustom(this IEnumerable<IVisual> children, Point point)
+            => children.Any(ctrl => ctrl.HitTestCustom(point));
+    }
 }
diff --git a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs
index e5bbebdec2..8c16dd0f70 100644
--- a/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs
@@ -129,6 +129,23 @@ namespace Avalonia.Controls.UnitTests.Primitives
             Assert.Equal(-1, target.SelectedIndex);
         }
 
+        [Fact]
+        public void SelectedIndex_Should_Be_Minus_1_Without_Initialize()
+        {
+            var items = new[]
+            {
+                new Item(),
+                new Item(),
+            };
+
+            var target = new ListBox();
+            target.Items = items;
+            target.Template = Template();
+            target.DataContext = new object();
+
+            Assert.Equal(-1, target.SelectedIndex);
+        }
+
         [Fact]
         public void SelectedIndex_Should_Be_0_After_Initialize_With_AlwaysSelected()
         {
diff --git a/tests/Avalonia.Controls.UnitTests/Primitives/ToggleButtonTests.cs b/tests/Avalonia.Controls.UnitTests/Primitives/ToggleButtonTests.cs
index 4f4ab47b0a..9acd42aba6 100644
--- a/tests/Avalonia.Controls.UnitTests/Primitives/ToggleButtonTests.cs
+++ b/tests/Avalonia.Controls.UnitTests/Primitives/ToggleButtonTests.cs
@@ -1,5 +1,4 @@
 using Avalonia.Data;
-using Avalonia.Markup.Data;
 using Avalonia.UnitTests;
 
 using Xunit;
@@ -63,6 +62,54 @@ namespace Avalonia.Controls.Primitives.UnitTests
             Assert.Null(threeStateButton.IsChecked);
         }
 
+        [Fact]
+        public void ToggleButton_Events_Are_Raised_On_Is_Checked_Changes()
+        {
+            var threeStateButton = new ToggleButton();
+
+            bool checkedRaised = false;
+            threeStateButton.Checked += (_, __) => checkedRaised = true;
+
+            threeStateButton.IsChecked = true;
+            Assert.True(checkedRaised);
+
+            bool uncheckedRaised = false;
+            threeStateButton.Unchecked += (_, __) => uncheckedRaised = true;
+
+            threeStateButton.IsChecked = false;
+            Assert.True(uncheckedRaised);
+
+            bool indeterminateRaised = false;
+            threeStateButton.Indeterminate += (_, __) => indeterminateRaised = true;
+
+            threeStateButton.IsChecked = null;
+            Assert.True(indeterminateRaised);
+        }
+
+        [Fact]
+        public void ToggleButton_Events_Are_Raised_When_Toggling()
+        {
+            var threeStateButton = new TestToggleButton { IsThreeState = true };
+
+            bool checkedRaised = false;
+            threeStateButton.Checked += (_, __) => checkedRaised = true;
+
+            threeStateButton.Toggle();
+            Assert.True(checkedRaised);
+
+            bool indeterminateRaised = false;
+            threeStateButton.Indeterminate += (_, __) => indeterminateRaised = true;
+
+            threeStateButton.Toggle();
+            Assert.True(indeterminateRaised);
+
+            bool uncheckedRaised = false;
+            threeStateButton.Unchecked += (_, __) => uncheckedRaised = true;
+
+            threeStateButton.Toggle();
+            Assert.True(uncheckedRaised);
+        }
+
         private class Class1 : NotifyingBase
         {
             private bool _foo;
@@ -80,5 +127,10 @@ namespace Avalonia.Controls.Primitives.UnitTests
                 set { nullableFoo = value; RaisePropertyChanged(); }
             }
         }
+
+        private class TestToggleButton : ToggleButton
+        {
+            public new void Toggle() => base.Toggle();
+        }
     }
 }