From 619d889b39d3f4ead2291fd700d63364b640f65b Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Sun, 23 Jan 2022 22:06:59 -0500
Subject: [PATCH 01/48] Add initial SplitButton code

---
 .../SplitButton/SplitButton.cs                | 600 ++++++++++++++++++
 .../SplitButton/SplitButtonClickEventArgs.cs  |  25 +
 2 files changed, 625 insertions(+)
 create mode 100644 src/Avalonia.Controls/SplitButton/SplitButton.cs
 create mode 100644 src/Avalonia.Controls/SplitButton/SplitButtonClickEventArgs.cs

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
new file mode 100644
index 0000000000..22098961bd
--- /dev/null
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -0,0 +1,600 @@
+using System;
+using System.Reactive.Disposables;
+using System.Windows.Input;
+using Avalonia.Controls.Primitives;
+using Avalonia.Input;
+using Avalonia.Interactivity;
+using Avalonia.LogicalTree;
+
+namespace Avalonia.Controls
+{
+    /// <summary>
+    /// A button with primary and secondary parts that can each be invoked separately.
+    /// The primary part behaves like a button and the secondary part opens a flyout.
+    /// </summary>
+    public class SplitButton : ContentControl, ICommandSource
+    {
+        /// <summary>
+        /// Raised when the user presses the primary part of the <see cref="SplitButton"/>.
+        /// </summary>
+        public event EventHandler<SplitButtonClickEventArgs> Click
+        {
+            add => AddHandler(ClickEvent, value);
+            remove => RemoveHandler(ClickEvent, value);
+        }
+
+        /// <summary>
+        /// Defines the <see cref="Click"/> event.
+        /// </summary>
+        public static readonly RoutedEvent<SplitButtonClickEventArgs> ClickEvent =
+            RoutedEvent.Register<SplitButton, SplitButtonClickEventArgs>(
+                nameof(Click),
+                RoutingStrategies.Bubble);
+
+        /// <summary>
+        /// Defines the <see cref="Command"/> property.
+        /// </summary>
+        public static readonly DirectProperty<SplitButton, ICommand> CommandProperty =
+            AvaloniaProperty.RegisterDirect<SplitButton, ICommand>(
+                nameof(Command),
+                splitButton => splitButton.Command,
+                (splitButton, command) => splitButton.Command = command,
+                enableDataValidation: true);
+
+        /// <summary>
+        /// Defines the <see cref="CommandParameter"/> property.
+        /// </summary>
+        public static readonly StyledProperty<object> CommandParameterProperty =
+            AvaloniaProperty.Register<SplitButton, object>(
+                nameof(CommandParameter));
+
+		/// <summary>
+		/// Defines the <see cref="Flyout"/> property
+		/// </summary>
+        public static readonly StyledProperty<FlyoutBase> FlyoutProperty =
+            AvaloniaProperty.Register<SplitButton, FlyoutBase>(
+                nameof(Flyout));
+
+        private ICommand _Command;
+
+        private Button _primaryButton   = null;
+        private Button _secondaryButton = null;
+
+        private bool        _commandCanExecute = true;
+        protected bool      _hasLoaded         = false;
+        private bool        _isFlyoutOpen      = false;
+        private bool        _isKeyDown         = false;
+        private PointerType _lastPointerType   = PointerType.Mouse;
+
+        private CompositeDisposable _buttonPropertyChangedDisposable;
+		private IDisposable         _flyoutPropertyChangedDisposable;
+
+        ////////////////////////////////////////////////////////////////////////
+        // 
+        // Constructor / Destructors
+        //
+        ////////////////////////////////////////////////////////////////////////
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="SplitButton"/> class.
+        /// </summary>
+        public SplitButton()
+        {
+        }
+
+        ////////////////////////////////////////////////////////////////////////
+        // 
+        // Properties
+        //
+        ////////////////////////////////////////////////////////////////////////
+
+		/// <summary>
+		/// Gets or sets the <see cref="ICommand"/> invoked when the primary part is pressed.
+		/// </summary>
+		public ICommand Command
+		{
+			get => _Command;
+			set => SetAndRaise(CommandProperty, ref _Command, value);
+		}
+
+		/// <summary>
+		/// Gets or sets a parameter to be passed to the <see cref="Command"/>.
+		/// </summary>
+		public object CommandParameter
+		{
+			get => GetValue(CommandParameterProperty);
+			set => SetValue(CommandParameterProperty, value);
+		}
+
+		/// <summary>
+		/// Gets or sets the <see cref="FlyoutBase"/> that is shown when the secondary part is pressed.
+		/// </summary>
+		public FlyoutBase Flyout
+		{
+            get => GetValue(FlyoutProperty);
+            set => SetValue(FlyoutProperty, value);
+		}
+
+        ////////////////////////////////////////////////////////////////////////
+        // 
+        // Methods
+        //
+        ////////////////////////////////////////////////////////////////////////
+
+        /// <inheritdoc/>
+        public void CanExecuteChanged(object sender, EventArgs e)
+        {
+            var canExecute = Command == null || Command.CanExecute(CommandParameter);
+
+            if (canExecute != _commandCanExecute)
+            {
+                _commandCanExecute = canExecute;
+                UpdateIsEffectivelyEnabled();
+            }
+        }
+
+        /// <inheritdoc/>
+        protected override bool IsEnabledCore => base.IsEnabledCore && _commandCanExecute;
+
+        /// <summary>
+        /// Updates the visual state of the control by applying latest PseudoClasses.
+        /// </summary>
+        private void UpdatePseudoClasses()
+        {
+            /*
+            // place the secondary button
+            if (m_lastPointerDeviceType == winrt::PointerDeviceType::Touch || m_isKeyDown)
+            {
+                winrt::VisualStateManager::GoToState(*this, L"SecondaryButtonSpan", useTransitions);
+            }
+            else
+            {
+                winrt::VisualStateManager::GoToState(*this, L"SecondaryButtonRight", useTransitions);
+            }
+
+            // change visual state
+            auto primaryButton = m_primaryButton.get();
+            auto secondaryButton = m_secondaryButton.get();
+
+            if (!IsEnabled())
+            {
+                winrt::VisualStateManager::GoToState(*this, L"Disabled", useTransitions);
+            }
+            else if (primaryButton && secondaryButton)
+            {
+                if (m_isFlyoutOpen)
+                {
+                    if (InternalIsChecked())
+                    {
+                        winrt::VisualStateManager::GoToState(*this, L"CheckedFlyoutOpen", useTransitions);
+                    }
+                    else
+                    {
+                        winrt::VisualStateManager::GoToState(*this, L"FlyoutOpen", useTransitions);
+                    }
+                }
+                // SplitButton and ToggleSplitButton share a template -- this section is driving the checked states for ToggleSplitButton.
+                else if (InternalIsChecked())
+                {
+                    if (m_lastPointerDeviceType == winrt::PointerDeviceType::Touch || m_isKeyDown)
+                    {
+                        if (primaryButton.IsPressed() || secondaryButton.IsPressed() || m_isKeyDown)
+                        {
+                            winrt::VisualStateManager::GoToState(*this, L"CheckedTouchPressed", useTransitions);
+                        }
+                        else
+                        {
+                            winrt::VisualStateManager::GoToState(*this, L"Checked", useTransitions);
+                        }
+                    }
+                    else if (primaryButton.IsPressed())
+                    {
+                        winrt::VisualStateManager::GoToState(*this, L"CheckedPrimaryPressed", useTransitions);
+                    }
+                    else if (primaryButton.IsPointerOver())
+                    {
+                        winrt::VisualStateManager::GoToState(*this, L"CheckedPrimaryPointerOver", useTransitions);
+                    }
+                    else if (secondaryButton.IsPressed())
+                    {
+                        winrt::VisualStateManager::GoToState(*this, L"CheckedSecondaryPressed", useTransitions);
+                    }
+                    else if (secondaryButton.IsPointerOver())
+                    {
+                        winrt::VisualStateManager::GoToState(*this, L"CheckedSecondaryPointerOver", useTransitions);
+                    }
+                    else
+                    {
+                        winrt::VisualStateManager::GoToState(*this, L"Checked", useTransitions);
+                    }
+                }
+                else
+                {
+                    if (m_lastPointerDeviceType == winrt::PointerDeviceType::Touch || m_isKeyDown)
+                    {
+                        if (primaryButton.IsPressed() || secondaryButton.IsPressed() || m_isKeyDown)
+                        {
+                            winrt::VisualStateManager::GoToState(*this, L"TouchPressed", useTransitions);
+                        }
+                        else
+                        {
+                            winrt::VisualStateManager::GoToState(*this, L"Normal", useTransitions);
+                        }
+                    }
+                    else if (primaryButton.IsPressed())
+                    {
+                        winrt::VisualStateManager::GoToState(*this, L"PrimaryPressed", useTransitions);
+                    }
+                    else if (primaryButton.IsPointerOver())
+                    {
+                        winrt::VisualStateManager::GoToState(*this, L"PrimaryPointerOver", useTransitions);
+                    }
+                    else if (secondaryButton.IsPressed())
+                    {
+                        winrt::VisualStateManager::GoToState(*this, L"SecondaryPressed", useTransitions);
+                    }
+                    else if (secondaryButton.IsPointerOver())
+                    {
+                        winrt::VisualStateManager::GoToState(*this, L"SecondaryPointerOver", useTransitions);
+                    }
+                    else
+                    {
+                        winrt::VisualStateManager::GoToState(*this, L"Normal", useTransitions);
+                    }
+                }
+            }
+            */
+        }
+
+        /// <summary>
+        /// Opens the secondary button's flyout.
+        /// </summary>
+        private void OpenFlyout()
+        {
+            if (Flyout != null)
+            {
+                Flyout.ShowAt(this);
+            }
+        }
+
+        /// <summary>
+        /// Closes the secondary button's flyout.
+        /// </summary>
+        private void CloseFlyout()
+        {
+            if (Flyout != null)
+            {
+                Flyout.Hide();
+            }
+        }
+
+        /// <summary>
+        /// Registers all flyout events.
+        /// </summary>
+        /// <param name="flyout">The flyout to connect events to.</param>
+        private void RegisterFlyoutEvents(FlyoutBase flyout)
+        {
+            if (flyout != null)
+            {
+                flyout.Opened += Flyout_Opened;
+                flyout.Closed += Flyout_Closed;
+
+                _flyoutPropertyChangedDisposable = flyout.GetPropertyChangedObservable(FlyoutBase.PlacementProperty).Subscribe(Flyout_PlacementPropertyChanged);
+            }
+        }
+
+        /// <summary>
+        /// Explicitly unregisters all flyout events.
+        /// </summary>
+        /// <param name="flyout">The flyout to disconnect events from.</param>
+        private void UnregisterFlyoutEvents(FlyoutBase flyout)
+        {
+            if (flyout != null)
+            {
+                flyout.Opened -= Flyout_Opened;
+                flyout.Closed -= Flyout_Closed;
+
+                _flyoutPropertyChangedDisposable?.Dispose();
+                _flyoutPropertyChangedDisposable = null;
+             }
+        }
+
+        /// <summary>
+        /// Explicitly unregisters all events related to the two buttons in OnApplyTemplate().
+        /// </summary>
+        private void UnregisterEvents()
+        {
+            _buttonPropertyChangedDisposable?.Dispose();
+            _buttonPropertyChangedDisposable = null;
+
+            if (_primaryButton != null)
+            {
+                _primaryButton.Click -= PrimaryButton_Click;
+
+                _primaryButton.PointerEnter       -= Button_PointerEvent;
+                _primaryButton.PointerLeave       -= Button_PointerEvent;
+                _primaryButton.PointerPressed     -= Button_PointerEvent;
+                _primaryButton.PointerReleased    -= Button_PointerEvent;
+                _primaryButton.PointerCaptureLost -= Button_PointerCaptureLost;
+            }
+
+            if (_secondaryButton != null)
+            {
+                _secondaryButton.Click -= SecondaryButton_Click;
+
+                _secondaryButton.PointerEnter       -= Button_PointerEvent;
+                _secondaryButton.PointerLeave       -= Button_PointerEvent;
+                _secondaryButton.PointerPressed     -= Button_PointerEvent;
+                _secondaryButton.PointerReleased    -= Button_PointerEvent;
+                _secondaryButton.PointerCaptureLost -= Button_PointerCaptureLost;
+            }
+        }
+
+        ////////////////////////////////////////////////////////////////////////
+        // 
+        // OnEvent Overridable Methods
+        //
+        ////////////////////////////////////////////////////////////////////////
+
+        /// <inheritdoc/>
+        protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
+		{
+            UnregisterEvents();
+            UnregisterFlyoutEvents(Flyout);
+
+			_primaryButton   = e.NameScope.Find<Button>("PrimaryButton");
+			_secondaryButton = e.NameScope.Find<Button>("SecondaryButton");
+
+            _buttonPropertyChangedDisposable = new CompositeDisposable();
+
+            if (_primaryButton != null)
+            {
+                _primaryButton.Click += PrimaryButton_Click;
+
+                _primaryButton.GetPropertyChangedObservable(Button.IsPressedProperty);
+
+				_buttonPropertyChangedDisposable.Add(_primaryButton.GetPropertyChangedObservable(Button.IsPressedProperty).Subscribe(Button_VisualPropertyChanged));
+                _buttonPropertyChangedDisposable.Add(_primaryButton.GetPropertyChangedObservable(Button.IsPointerOverProperty).Subscribe(Button_VisualPropertyChanged));
+
+                // Register for pointer events to keep track of the last used pointer type and update visual states
+                _primaryButton.PointerEnter       += Button_PointerEvent;
+                _primaryButton.PointerLeave       += Button_PointerEvent;
+                _primaryButton.PointerPressed     += Button_PointerEvent;
+                _primaryButton.PointerReleased    += Button_PointerEvent;
+                _primaryButton.PointerCaptureLost += Button_PointerCaptureLost;
+            }
+
+            if (_secondaryButton != null)
+            {
+                _secondaryButton.Click += SecondaryButton_Click;
+
+                _buttonPropertyChangedDisposable.Add(_secondaryButton.GetPropertyChangedObservable(Button.IsPressedProperty).Subscribe(Button_VisualPropertyChanged));
+                _buttonPropertyChangedDisposable.Add(_secondaryButton.GetPropertyChangedObservable(Button.IsPointerOverProperty).Subscribe(Button_VisualPropertyChanged));
+
+                // Register for pointer events to keep track of the last used pointer type and update visual states
+                _secondaryButton.PointerEnter       += Button_PointerEvent;
+                _secondaryButton.PointerLeave       += Button_PointerEvent;
+                _secondaryButton.PointerPressed     += Button_PointerEvent;
+                _secondaryButton.PointerReleased    += Button_PointerEvent;
+                _secondaryButton.PointerCaptureLost += Button_PointerCaptureLost;
+            }
+
+            RegisterFlyoutEvents(Flyout);
+            UpdatePseudoClasses();
+
+            _hasLoaded = true;
+        }
+
+        /// <inheritdoc/>
+        protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
+        {
+            base.OnAttachedToVisualTree(e);
+        }
+
+        /// <inheritdoc/>
+        protected override void OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs e)
+        {
+            base.OnDetachedFromVisualTree(e);
+        }
+
+        /// <inheritdoc/>
+        protected override void OnAttachedToLogicalTree(LogicalTreeAttachmentEventArgs e)
+        {
+            base.OnAttachedToLogicalTree(e);
+        }
+
+        /// <inheritdoc/>
+        protected override void OnDetachedFromLogicalTree(LogicalTreeAttachmentEventArgs e)
+        {
+            base.OnDetachedFromLogicalTree(e);
+        }
+
+        /// <inheritdoc/>
+		protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> changedEventArgs)
+		{
+            if (changedEventArgs.Property == FlyoutProperty)
+            {
+                // Must unregister events here while a ref to the old flyout still exists
+                if (changedEventArgs.OldValue.GetValueOrDefault() is FlyoutBase oldFlyout)
+				{
+                    UnregisterFlyoutEvents(oldFlyout);
+                }
+
+                if (changedEventArgs.NewValue.GetValueOrDefault() is FlyoutBase newFlyout)
+                {
+                    RegisterFlyoutEvents(newFlyout);
+                }
+
+                UpdatePseudoClasses();
+            }
+
+			base.OnPropertyChanged(changedEventArgs);
+		}
+
+        /// <inheritdoc/>
+		protected override void OnKeyDown(KeyEventArgs e)
+		{
+            var key = e.Key;
+
+            if (key == Key.Space || key == Key.Enter) // Key.GamepadA is not currently supported
+            {
+                _isKeyDown = true;
+                UpdatePseudoClasses();
+            }
+
+			base.OnKeyDown(e);
+		}
+
+        /// <inheritdoc/>
+		protected override void OnKeyUp(KeyEventArgs e)
+		{
+            var key = e.Key;
+
+            if (key == Key.Space || key == Key.Enter) // Key.GamepadA is not currently supported
+            {
+                _isKeyDown = false;
+                UpdatePseudoClasses();
+
+                // Consider this a click on the primary button
+                if (IsEffectivelyEnabled)
+                {
+                    OnClickPrimary(null);
+                    e.Handled = true;
+                }
+            }
+            else if (key == Key.Down && IsEffectivelyEnabled)
+            {
+                // WinUI requires the VirtualKey.Menu (alt) + VirtualKey.Down to open the flyout
+                // Avalonia will only require Key.Down which is better cross-platform
+
+                OpenFlyout();
+                e.Handled = true;
+            }
+            else if (key == Key.F4 && IsEffectivelyEnabled)
+            {
+                OpenFlyout();
+                e.Handled = true;
+            }
+
+            base.OnKeyUp(e);
+        }
+
+        /// <summary>
+        /// Invokes the <see cref="Click"/> when the primary button part is clicked.
+        /// </summary>
+        /// <param name="e">The event args from the internal Click event.</param>
+        protected virtual void OnClickPrimary(RoutedEventArgs e)
+        {
+            // Note: It is not currently required to check enabled status; however, this is a failsafe
+            if (IsEffectivelyEnabled)
+            {
+                var eventArgs = new SplitButtonClickEventArgs(ClickEvent);
+                RaiseEvent(eventArgs);
+
+                if (!eventArgs.Handled && Command?.CanExecute(CommandParameter) == true)
+                {
+                    Command.Execute(CommandParameter);
+                    eventArgs.Handled = true;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Invoked when the secondary button part is clicked.
+        /// </summary>
+        /// <param name="e">The event args from the internal Click event.</param>
+        protected virtual void OnClickSecondary(RoutedEventArgs e)
+        {
+            // Note: It is not currently required to check enabled status; however, this is a failsafe
+            if (IsEffectivelyEnabled)
+            {
+                OpenFlyout();
+            }
+        }
+
+        ////////////////////////////////////////////////////////////////////////
+        // 
+        // Event Handling
+        //
+        ////////////////////////////////////////////////////////////////////////
+
+        /// <summary>
+        /// Event handler for when the internal primary button part is pressed.
+        /// </summary>
+        private void PrimaryButton_Click(object sender, RoutedEventArgs e)
+        {
+            OnClickPrimary(e);
+        }
+
+        /// <summary>
+        /// Event handler for when the internal secondary button part is pressed.
+        /// </summary>
+        private void SecondaryButton_Click(object sender, RoutedEventArgs e)
+        {
+            OnClickSecondary(e);
+        }
+
+        /// <summary>
+        /// Event handler for when pointer events occur in the primary or secondary buttons.
+        /// </summary>
+        private void Button_PointerEvent(object sender, PointerEventArgs e)
+		{
+            // Warning: Code must match with Button_PointerCaptureLost
+			if (_lastPointerType != e.Pointer.Type)
+			{
+				_lastPointerType = e.Pointer.Type;
+				UpdatePseudoClasses();
+			}
+		}
+
+        /// <summary>
+        /// Event handler for when the pointer capture is lost in the primary or secondary buttons.
+        /// </summary>
+        /// <remarks>
+        /// In upstream WinUI this is not a separate event handler. However, Avalonia has different args.
+        /// </remarks>
+		private void Button_PointerCaptureLost(object sender, PointerCaptureLostEventArgs e)
+		{
+            // Warning: Code must match with Button_PointerEvent
+			if (_lastPointerType != e.Pointer.Type)
+			{
+				_lastPointerType = e.Pointer.Type;
+				UpdatePseudoClasses();
+			}
+		}
+
+        /// <summary>
+        /// Called when a primary or secondary button property changes that affects the visual states.
+        /// </summary>
+        private void Button_VisualPropertyChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            UpdatePseudoClasses();
+        }
+
+        /// <summary>
+        /// Called when the <see cref="FlyoutBase.Placement"/> property changes.
+        /// </summary>
+        private void Flyout_PlacementPropertyChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            UpdatePseudoClasses();
+        }
+
+        /// <summary>
+        /// Event handler for when the split button's flyout is opened.
+        /// </summary>
+        private void Flyout_Opened(object sender, EventArgs e)
+        {
+            _isFlyoutOpen = true;
+            UpdatePseudoClasses();
+        }
+
+        /// <summary>
+        /// Event handler for when the split button's flyout is closed.
+        /// </summary>
+        private void Flyout_Closed(object sender, EventArgs e)
+        {
+            _isFlyoutOpen = false;
+            UpdatePseudoClasses();
+        }
+    }
+}
diff --git a/src/Avalonia.Controls/SplitButton/SplitButtonClickEventArgs.cs b/src/Avalonia.Controls/SplitButton/SplitButtonClickEventArgs.cs
new file mode 100644
index 0000000000..0359fb2f53
--- /dev/null
+++ b/src/Avalonia.Controls/SplitButton/SplitButtonClickEventArgs.cs
@@ -0,0 +1,25 @@
+using Avalonia.Interactivity;
+
+namespace Avalonia.Controls
+{
+    /// <summary>
+    /// Provides event data for the <see cref="SplitButton.Click"/> event.
+    /// </summary>
+    public class SplitButtonClickEventArgs : RoutedEventArgs
+    {
+        public SplitButtonClickEventArgs()
+        {
+        }
+
+        public SplitButtonClickEventArgs(RoutedEvent? routedEvent)
+        {
+            RoutedEvent = routedEvent;
+        }
+
+        public SplitButtonClickEventArgs(RoutedEvent? routedEvent, IInteractive? source)
+        {
+            RoutedEvent = routedEvent;
+            Source = source;
+        }
+    }
+}

From d1ea7b1ec9a571c60ea6bb1bbccc0e8b41e2b5c2 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Sun, 23 Jan 2022 22:07:36 -0500
Subject: [PATCH 02/48] Add empty SplitButtonPage in ControlCatalog

---
 samples/ControlCatalog/MainView.xaml           |  3 +++
 .../ControlCatalog/Pages/SplitButtonPage.xaml  |  6 ++++++
 .../Pages/SplitButtonPage.xaml.cs              | 18 ++++++++++++++++++
 3 files changed, 27 insertions(+)
 create mode 100644 samples/ControlCatalog/Pages/SplitButtonPage.xaml
 create mode 100644 samples/ControlCatalog/Pages/SplitButtonPage.xaml.cs

diff --git a/samples/ControlCatalog/MainView.xaml b/samples/ControlCatalog/MainView.xaml
index 3d869bb723..a4246e946a 100644
--- a/samples/ControlCatalog/MainView.xaml
+++ b/samples/ControlCatalog/MainView.xaml
@@ -121,6 +121,9 @@
       <TabItem Header="Slider">
         <pages:SliderPage />
       </TabItem>
+      <TabItem Header="SplitButton">
+        <pages:SplitButtonPage />
+      </TabItem>
       <TabItem Header="SplitView">
         <pages:SplitViewPage />
       </TabItem>
diff --git a/samples/ControlCatalog/Pages/SplitButtonPage.xaml b/samples/ControlCatalog/Pages/SplitButtonPage.xaml
new file mode 100644
index 0000000000..a2e12a1528
--- /dev/null
+++ b/samples/ControlCatalog/Pages/SplitButtonPage.xaml
@@ -0,0 +1,6 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             x:Class="ControlCatalog.Pages.SplitButtonPage">
+  <StackPanel Orientation="Vertical" Spacing="4">
+  </StackPanel>
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/SplitButtonPage.xaml.cs b/samples/ControlCatalog/Pages/SplitButtonPage.xaml.cs
new file mode 100644
index 0000000000..64b686008f
--- /dev/null
+++ b/samples/ControlCatalog/Pages/SplitButtonPage.xaml.cs
@@ -0,0 +1,18 @@
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+
+namespace ControlCatalog.Pages
+{
+    public class SplitButtonPage : UserControl
+    {
+        public SplitButtonPage()
+        {
+            InitializeComponent();
+        }
+
+        private void InitializeComponent()
+        {
+            AvaloniaXamlLoader.Load(this);
+        }
+    }
+}

From ac1d261d4c8f17d9df04e569b630ecfe1d3e25e2 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Sun, 23 Jan 2022 22:50:29 -0500
Subject: [PATCH 03/48] Tabs to spaces

---
 .../SplitButton/SplitButton.cs                | 116 +++++++++---------
 1 file changed, 58 insertions(+), 58 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index 22098961bd..d3450b332f 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -48,9 +48,9 @@ namespace Avalonia.Controls
             AvaloniaProperty.Register<SplitButton, object>(
                 nameof(CommandParameter));
 
-		/// <summary>
-		/// Defines the <see cref="Flyout"/> property
-		/// </summary>
+        /// <summary>
+        /// Defines the <see cref="Flyout"/> property
+        /// </summary>
         public static readonly StyledProperty<FlyoutBase> FlyoutProperty =
             AvaloniaProperty.Register<SplitButton, FlyoutBase>(
                 nameof(Flyout));
@@ -67,7 +67,7 @@ namespace Avalonia.Controls
         private PointerType _lastPointerType   = PointerType.Mouse;
 
         private CompositeDisposable _buttonPropertyChangedDisposable;
-		private IDisposable         _flyoutPropertyChangedDisposable;
+        private IDisposable         _flyoutPropertyChangedDisposable;
 
         ////////////////////////////////////////////////////////////////////////
         // 
@@ -88,32 +88,32 @@ namespace Avalonia.Controls
         //
         ////////////////////////////////////////////////////////////////////////
 
-		/// <summary>
-		/// Gets or sets the <see cref="ICommand"/> invoked when the primary part is pressed.
-		/// </summary>
-		public ICommand Command
-		{
-			get => _Command;
-			set => SetAndRaise(CommandProperty, ref _Command, value);
-		}
-
-		/// <summary>
-		/// Gets or sets a parameter to be passed to the <see cref="Command"/>.
-		/// </summary>
-		public object CommandParameter
-		{
-			get => GetValue(CommandParameterProperty);
-			set => SetValue(CommandParameterProperty, value);
-		}
-
-		/// <summary>
-		/// Gets or sets the <see cref="FlyoutBase"/> that is shown when the secondary part is pressed.
-		/// </summary>
-		public FlyoutBase Flyout
-		{
+        /// <summary>
+        /// Gets or sets the <see cref="ICommand"/> invoked when the primary part is pressed.
+        /// </summary>
+        public ICommand Command
+        {
+            get => _Command;
+            set => SetAndRaise(CommandProperty, ref _Command, value);
+        }
+
+        /// <summary>
+        /// Gets or sets a parameter to be passed to the <see cref="Command"/>.
+        /// </summary>
+        public object CommandParameter
+        {
+            get => GetValue(CommandParameterProperty);
+            set => SetValue(CommandParameterProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the <see cref="FlyoutBase"/> that is shown when the secondary part is pressed.
+        /// </summary>
+        public FlyoutBase Flyout
+        {
             get => GetValue(FlyoutProperty);
             set => SetValue(FlyoutProperty, value);
-		}
+        }
 
         ////////////////////////////////////////////////////////////////////////
         // 
@@ -338,12 +338,12 @@ namespace Avalonia.Controls
 
         /// <inheritdoc/>
         protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
-		{
+        {
             UnregisterEvents();
             UnregisterFlyoutEvents(Flyout);
 
-			_primaryButton   = e.NameScope.Find<Button>("PrimaryButton");
-			_secondaryButton = e.NameScope.Find<Button>("SecondaryButton");
+            _primaryButton   = e.NameScope.Find<Button>("PrimaryButton");
+            _secondaryButton = e.NameScope.Find<Button>("SecondaryButton");
 
             _buttonPropertyChangedDisposable = new CompositeDisposable();
 
@@ -353,7 +353,7 @@ namespace Avalonia.Controls
 
                 _primaryButton.GetPropertyChangedObservable(Button.IsPressedProperty);
 
-				_buttonPropertyChangedDisposable.Add(_primaryButton.GetPropertyChangedObservable(Button.IsPressedProperty).Subscribe(Button_VisualPropertyChanged));
+                _buttonPropertyChangedDisposable.Add(_primaryButton.GetPropertyChangedObservable(Button.IsPressedProperty).Subscribe(Button_VisualPropertyChanged));
                 _buttonPropertyChangedDisposable.Add(_primaryButton.GetPropertyChangedObservable(Button.IsPointerOverProperty).Subscribe(Button_VisualPropertyChanged));
 
                 // Register for pointer events to keep track of the last used pointer type and update visual states
@@ -410,13 +410,13 @@ namespace Avalonia.Controls
         }
 
         /// <inheritdoc/>
-		protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> changedEventArgs)
-		{
+        protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> changedEventArgs)
+        {
             if (changedEventArgs.Property == FlyoutProperty)
             {
                 // Must unregister events here while a ref to the old flyout still exists
                 if (changedEventArgs.OldValue.GetValueOrDefault() is FlyoutBase oldFlyout)
-				{
+                {
                     UnregisterFlyoutEvents(oldFlyout);
                 }
 
@@ -428,12 +428,12 @@ namespace Avalonia.Controls
                 UpdatePseudoClasses();
             }
 
-			base.OnPropertyChanged(changedEventArgs);
-		}
+            base.OnPropertyChanged(changedEventArgs);
+        }
 
         /// <inheritdoc/>
-		protected override void OnKeyDown(KeyEventArgs e)
-		{
+        protected override void OnKeyDown(KeyEventArgs e)
+        {
             var key = e.Key;
 
             if (key == Key.Space || key == Key.Enter) // Key.GamepadA is not currently supported
@@ -442,12 +442,12 @@ namespace Avalonia.Controls
                 UpdatePseudoClasses();
             }
 
-			base.OnKeyDown(e);
-		}
+            base.OnKeyDown(e);
+        }
 
         /// <inheritdoc/>
-		protected override void OnKeyUp(KeyEventArgs e)
-		{
+        protected override void OnKeyUp(KeyEventArgs e)
+        {
             var key = e.Key;
 
             if (key == Key.Space || key == Key.Enter) // Key.GamepadA is not currently supported
@@ -538,14 +538,14 @@ namespace Avalonia.Controls
         /// Event handler for when pointer events occur in the primary or secondary buttons.
         /// </summary>
         private void Button_PointerEvent(object sender, PointerEventArgs e)
-		{
+        {
             // Warning: Code must match with Button_PointerCaptureLost
-			if (_lastPointerType != e.Pointer.Type)
-			{
-				_lastPointerType = e.Pointer.Type;
-				UpdatePseudoClasses();
-			}
-		}
+            if (_lastPointerType != e.Pointer.Type)
+            {
+                _lastPointerType = e.Pointer.Type;
+                UpdatePseudoClasses();
+            }
+        }
 
         /// <summary>
         /// Event handler for when the pointer capture is lost in the primary or secondary buttons.
@@ -553,15 +553,15 @@ namespace Avalonia.Controls
         /// <remarks>
         /// In upstream WinUI this is not a separate event handler. However, Avalonia has different args.
         /// </remarks>
-		private void Button_PointerCaptureLost(object sender, PointerCaptureLostEventArgs e)
-		{
+        private void Button_PointerCaptureLost(object sender, PointerCaptureLostEventArgs e)
+        {
             // Warning: Code must match with Button_PointerEvent
-			if (_lastPointerType != e.Pointer.Type)
-			{
-				_lastPointerType = e.Pointer.Type;
-				UpdatePseudoClasses();
-			}
-		}
+            if (_lastPointerType != e.Pointer.Type)
+            {
+                _lastPointerType = e.Pointer.Type;
+                UpdatePseudoClasses();
+            }
+        }
 
         /// <summary>
         /// Called when a primary or secondary button property changes that affects the visual states.

From 63f1aa8cd6c0b98d9eeb44abf51af04ce4210987 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Mon, 24 Jan 2022 14:22:48 -0500
Subject: [PATCH 04/48] Add Fluent v1 default style for SplitButton

---
 .../SplitButton/SplitButton.cs                | 141 ++++---
 .../Accents/FluentControlResourcesDark.xaml   |  27 ++
 .../Accents/FluentControlResourcesLight.xaml  |  27 ++
 .../Controls/FluentControls.xaml              |   1 +
 .../Controls/SplitButton.xaml                 | 370 ++++++++++++++++++
 5 files changed, 520 insertions(+), 46 deletions(-)
 create mode 100644 src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index d3450b332f..4af8b44629 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Reactive.Disposables;
 using System.Windows.Input;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -12,6 +13,7 @@ namespace Avalonia.Controls
     /// A button with primary and secondary parts that can each be invoked separately.
     /// The primary part behaves like a button and the secondary part opens a flyout.
     /// </summary>
+    //[PseudoClasses(":pressed")]
     public class SplitButton : ContentControl, ICommandSource
     {
         /// <summary>
@@ -141,109 +143,156 @@ namespace Avalonia.Controls
         /// </summary>
         private void UpdatePseudoClasses()
         {
-            /*
-            // place the secondary button
-            if (m_lastPointerDeviceType == winrt::PointerDeviceType::Touch || m_isKeyDown)
+            bool internalIsChecked = false;
+
+            string pcNormal   = ":normal";
+            string pcDisabled = ":disabled";
+
+            string pcSecondaryButtonRight = ":secondaryButtonRight";
+            string pcSecondaryButtonSpan  = ":secondaryButtonSpan";
+
+            string pcCheckedFlyoutOpen = ":checkedFlyoutOpen";
+            string pcFlyoutOpen        = ":flyoutOpen";
+
+            string pcCheckedTouchPressed         = ":checkedTouchPressed";
+            string pcChecked                     = ":checked";
+            string pcCheckedPrimaryPressed       = ":checkedPrimaryPressed";
+            string pcCheckedPrimaryPointerOver   = ":checkedPrimaryPointerOver";
+            string pcCheckedSecondaryPressed     = ":checkedSecondaryPressed";
+            string pcCheckedSecondaryPointerOver = ":checkedSecondaryPointerOver";
+
+            string pcTouchPressed         = ":touchPressed";
+            string pcPrimaryPressed       = ":primaryPressed";
+            string pcPrimaryPointerOver   = ":primaryPointerOver";
+            string pcSecondaryPressed     = ":secondaryPressed";
+            string pcSecondaryPointerOver = ":secondaryPointerOver";
+
+            // Place the secondary button
+            // These are mutually exclusive PseudoClasses handled separately from SetExclusivePseudoClass().
+            // They must be applied in addition to the others.
+            if (_lastPointerType == PointerType.Touch || _isKeyDown)
             {
-                winrt::VisualStateManager::GoToState(*this, L"SecondaryButtonSpan", useTransitions);
+                PseudoClasses.Set(pcSecondaryButtonSpan, true);
+                PseudoClasses.Set(pcSecondaryButtonRight, false);
             }
             else
             {
-                winrt::VisualStateManager::GoToState(*this, L"SecondaryButtonRight", useTransitions);
+                PseudoClasses.Set(pcSecondaryButtonSpan, false);
+                PseudoClasses.Set(pcSecondaryButtonRight, true);
             }
 
-            // change visual state
-            auto primaryButton = m_primaryButton.get();
-            auto secondaryButton = m_secondaryButton.get();
-
-            if (!IsEnabled())
+            // Change the visual state
+            if (!IsEnabled)
             {
-                winrt::VisualStateManager::GoToState(*this, L"Disabled", useTransitions);
+                SetExclusivePseudoClass(pcDisabled);
             }
-            else if (primaryButton && secondaryButton)
+            else if (_primaryButton != null && _secondaryButton != null)
             {
-                if (m_isFlyoutOpen)
+                if (_isFlyoutOpen)
                 {
-                    if (InternalIsChecked())
+                    if (internalIsChecked)
                     {
-                        winrt::VisualStateManager::GoToState(*this, L"CheckedFlyoutOpen", useTransitions);
+                        SetExclusivePseudoClass(pcCheckedFlyoutOpen);
                     }
                     else
                     {
-                        winrt::VisualStateManager::GoToState(*this, L"FlyoutOpen", useTransitions);
+                        SetExclusivePseudoClass(pcFlyoutOpen);
                     }
                 }
                 // SplitButton and ToggleSplitButton share a template -- this section is driving the checked states for ToggleSplitButton.
-                else if (InternalIsChecked())
+                else if (internalIsChecked)
                 {
-                    if (m_lastPointerDeviceType == winrt::PointerDeviceType::Touch || m_isKeyDown)
+                    if (_lastPointerType == PointerType.Touch || _isKeyDown)
                     {
-                        if (primaryButton.IsPressed() || secondaryButton.IsPressed() || m_isKeyDown)
+                        if (_primaryButton.IsPressed || _secondaryButton.IsPressed || _isKeyDown)
                         {
-                            winrt::VisualStateManager::GoToState(*this, L"CheckedTouchPressed", useTransitions);
+                            SetExclusivePseudoClass(pcCheckedTouchPressed);
                         }
                         else
                         {
-                            winrt::VisualStateManager::GoToState(*this, L"Checked", useTransitions);
+                            SetExclusivePseudoClass(pcChecked);
                         }
                     }
-                    else if (primaryButton.IsPressed())
+                    else if (_primaryButton.IsPressed)
                     {
-                        winrt::VisualStateManager::GoToState(*this, L"CheckedPrimaryPressed", useTransitions);
+                        SetExclusivePseudoClass(pcCheckedPrimaryPressed);
                     }
-                    else if (primaryButton.IsPointerOver())
+                    else if (_primaryButton.IsPointerOver)
                     {
-                        winrt::VisualStateManager::GoToState(*this, L"CheckedPrimaryPointerOver", useTransitions);
+                        SetExclusivePseudoClass(pcCheckedPrimaryPointerOver);
                     }
-                    else if (secondaryButton.IsPressed())
+                    else if (_secondaryButton.IsPressed)
                     {
-                        winrt::VisualStateManager::GoToState(*this, L"CheckedSecondaryPressed", useTransitions);
+                        SetExclusivePseudoClass(pcCheckedSecondaryPressed);
                     }
-                    else if (secondaryButton.IsPointerOver())
+                    else if (_secondaryButton.IsPointerOver)
                     {
-                        winrt::VisualStateManager::GoToState(*this, L"CheckedSecondaryPointerOver", useTransitions);
+                        SetExclusivePseudoClass(pcCheckedSecondaryPointerOver);
                     }
                     else
                     {
-                        winrt::VisualStateManager::GoToState(*this, L"Checked", useTransitions);
+                        SetExclusivePseudoClass(pcChecked);
                     }
                 }
                 else
                 {
-                    if (m_lastPointerDeviceType == winrt::PointerDeviceType::Touch || m_isKeyDown)
+                    if (_lastPointerType == PointerType.Touch || _isKeyDown)
                     {
-                        if (primaryButton.IsPressed() || secondaryButton.IsPressed() || m_isKeyDown)
+                        if (_primaryButton.IsPressed || _secondaryButton.IsPressed || _isKeyDown)
                         {
-                            winrt::VisualStateManager::GoToState(*this, L"TouchPressed", useTransitions);
+                            SetExclusivePseudoClass(pcTouchPressed);
                         }
                         else
                         {
-                            winrt::VisualStateManager::GoToState(*this, L"Normal", useTransitions);
+                            SetExclusivePseudoClass(pcNormal);
                         }
                     }
-                    else if (primaryButton.IsPressed())
+                    else if (_primaryButton.IsPressed)
                     {
-                        winrt::VisualStateManager::GoToState(*this, L"PrimaryPressed", useTransitions);
+                        SetExclusivePseudoClass(pcPrimaryPressed);
                     }
-                    else if (primaryButton.IsPointerOver())
+                    else if (_primaryButton.IsPointerOver)
                     {
-                        winrt::VisualStateManager::GoToState(*this, L"PrimaryPointerOver", useTransitions);
+                        SetExclusivePseudoClass(pcPrimaryPointerOver);
                     }
-                    else if (secondaryButton.IsPressed())
+                    else if (_secondaryButton.IsPressed)
                     {
-                        winrt::VisualStateManager::GoToState(*this, L"SecondaryPressed", useTransitions);
+                        SetExclusivePseudoClass(pcSecondaryPressed);
                     }
-                    else if (secondaryButton.IsPointerOver())
+                    else if (_secondaryButton.IsPointerOver)
                     {
-                        winrt::VisualStateManager::GoToState(*this, L"SecondaryPointerOver", useTransitions);
+                        SetExclusivePseudoClass(pcSecondaryPointerOver);
                     }
                     else
                     {
-                        winrt::VisualStateManager::GoToState(*this, L"Normal", useTransitions);
+                        SetExclusivePseudoClass(pcNormal);
                     }
                 }
             }
-            */
+
+            // Local function to enable the specified PseudoClass and disable all others
+            // This more closely matches the VisualStateManager of WinUI where the default style originated
+            void SetExclusivePseudoClass(string pseudoClass = "")
+            {
+                PseudoClasses.Set(pcNormal, pseudoClass == pcNormal);
+                PseudoClasses.Set(pcDisabled, pseudoClass == pcDisabled);
+
+                PseudoClasses.Set(pcCheckedFlyoutOpen, pseudoClass == pcCheckedFlyoutOpen);
+                PseudoClasses.Set(pcFlyoutOpen, pseudoClass == pcFlyoutOpen);
+
+                PseudoClasses.Set(pcCheckedTouchPressed, pseudoClass == pcCheckedTouchPressed);
+                PseudoClasses.Set(pcChecked, pseudoClass == pcChecked);
+                PseudoClasses.Set(pcCheckedPrimaryPressed, pseudoClass == pcCheckedPrimaryPressed);
+                PseudoClasses.Set(pcCheckedPrimaryPointerOver, pseudoClass == pcCheckedPrimaryPointerOver);
+                PseudoClasses.Set(pcCheckedSecondaryPressed, pseudoClass == pcCheckedSecondaryPressed);
+                PseudoClasses.Set(pcCheckedSecondaryPointerOver, pseudoClass == pcCheckedSecondaryPointerOver);
+
+                PseudoClasses.Set(pcTouchPressed, pseudoClass == pcTouchPressed);
+                PseudoClasses.Set(pcPrimaryPressed, pseudoClass == pcPrimaryPressed);
+                PseudoClasses.Set(pcPrimaryPointerOver, pseudoClass == pcPrimaryPointerOver);
+                PseudoClasses.Set(pcSecondaryPressed, pseudoClass == pcSecondaryPressed);
+                PseudoClasses.Set(pcSecondaryPointerOver, pseudoClass == pcSecondaryPointerOver);
+            }
         }
 
         /// <summary>
@@ -342,8 +391,8 @@ namespace Avalonia.Controls
             UnregisterEvents();
             UnregisterFlyoutEvents(Flyout);
 
-            _primaryButton   = e.NameScope.Find<Button>("PrimaryButton");
-            _secondaryButton = e.NameScope.Find<Button>("SecondaryButton");
+            _primaryButton   = e.NameScope.Find<Button>("PART_PrimaryButton");
+            _secondaryButton = e.NameScope.Find<Button>("PART_SecondaryButton");
 
             _buttonPropertyChangedDisposable = new CompositeDisposable();
 
diff --git a/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesDark.xaml b/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesDark.xaml
index a1f423c059..085b03c96f 100644
--- a/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesDark.xaml
+++ b/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesDark.xaml
@@ -556,6 +556,33 @@
     <Thickness x:Key="TreeViewItemBorderThemeThickness">1</Thickness>
     <x:Double x:Key="TreeViewItemMinHeight">32</x:Double>
 
+    <!-- Resources for SplitButton.xaml -->
+    <StaticResource x:Key="SplitButtonBackground" ResourceKey="SystemControlBackgroundBaseLowBrush" />
+    <SolidColorBrush x:Key="SplitButtonBackgroundPointerOver" Color="{StaticResource SystemBaseHighColor}" Opacity="0.1" />
+    <StaticResource x:Key="SplitButtonBackgroundPressed" ResourceKey="SystemControlBackgroundBaseMediumLowBrush" />
+    <StaticResource x:Key="SplitButtonBackgroundDisabled" ResourceKey="SystemControlBackgroundBaseLowBrush" />
+    <StaticResource x:Key="SplitButtonBackgroundChecked" ResourceKey="SystemControlHighlightAccentBrush" />
+    <StaticResource x:Key="SplitButtonBackgroundCheckedPointerOver" ResourceKey="SystemAccentColorDark1" />
+    <StaticResource x:Key="SplitButtonBackgroundCheckedPressed" ResourceKey="SystemAccentColorLight1" />
+    <StaticResource x:Key="SplitButtonBackgroundCheckedDisabled" ResourceKey="SystemControlBackgroundBaseLowBrush" />
+    <StaticResource x:Key="SplitButtonForeground" ResourceKey="SystemControlForegroundBaseHighBrush" />
+    <StaticResource x:Key="SplitButtonForegroundPointerOver" ResourceKey="SystemControlHighlightBaseHighBrush" />
+    <StaticResource x:Key="SplitButtonForegroundPressed" ResourceKey="SystemControlHighlightBaseHighBrush" />
+    <StaticResource x:Key="SplitButtonForegroundDisabled" ResourceKey="SystemControlDisabledBaseMediumLowBrush" />
+    <StaticResource x:Key="SplitButtonForegroundChecked" ResourceKey="SystemControlHighlightAltChromeWhiteBrush" />
+    <StaticResource x:Key="SplitButtonForegroundCheckedPointerOver" ResourceKey="SystemControlHighlightAltChromeWhiteBrush" />
+    <StaticResource x:Key="SplitButtonForegroundCheckedPressed" ResourceKey="SystemControlHighlightAltChromeWhiteBrush" />
+    <StaticResource x:Key="SplitButtonForegroundCheckedDisabled" ResourceKey="SystemControlDisabledBaseMediumLowBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrush" ResourceKey="SystemControlForegroundTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushPointerOver" ResourceKey="SystemControlForegroundTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushPressed" ResourceKey="SystemControlHighlightTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushDisabled" ResourceKey="SystemControlDisabledTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushChecked" ResourceKey="SystemControlHighlightAltTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushCheckedPointerOver" ResourceKey="SystemControlHighlightAltTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushCheckedPressed" ResourceKey="SystemControlHighlightAltTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushCheckedDisabled" ResourceKey="SystemControlDisabledTransparentBrush" />
+    <Thickness x:Key="SplitButtonBorderThemeThickness">1</Thickness>
+
     <!-- Resources for SplitView.xaml -->
     <StaticResource x:Key="SplitViewLightDismissOverlayBackground" ResourceKey="SystemControlPageBackgroundMediumAltMediumBrush" />
   
diff --git a/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesLight.xaml b/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesLight.xaml
index f75af76144..702d2c60bc 100644
--- a/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesLight.xaml
+++ b/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesLight.xaml
@@ -550,6 +550,33 @@
     <Thickness x:Key="TreeViewItemBorderThemeThickness">1</Thickness>
     <x:Double x:Key="TreeViewItemMinHeight">32</x:Double>
 
+    <!-- Resources for SplitButton.xaml -->
+    <StaticResource x:Key="SplitButtonBackground" ResourceKey="SystemControlBackgroundBaseLowBrush" />
+    <SolidColorBrush x:Key="SplitButtonBackgroundPointerOver" Color="{StaticResource SystemBaseHighColor}" Opacity="0.1" />
+    <StaticResource x:Key="SplitButtonBackgroundPressed" ResourceKey="SystemControlBackgroundBaseMediumLowBrush" />
+    <StaticResource x:Key="SplitButtonBackgroundDisabled" ResourceKey="SystemControlBackgroundBaseLowBrush" />
+    <StaticResource x:Key="SplitButtonBackgroundChecked" ResourceKey="SystemControlHighlightAccentBrush" />
+    <StaticResource x:Key="SplitButtonBackgroundCheckedPointerOver" ResourceKey="SystemAccentColorLight1" />
+    <StaticResource x:Key="SplitButtonBackgroundCheckedPressed" ResourceKey="SystemAccentColorDark1" />
+    <StaticResource x:Key="SplitButtonBackgroundCheckedDisabled" ResourceKey="SystemControlBackgroundBaseLowBrush" />
+    <StaticResource x:Key="SplitButtonForeground" ResourceKey="SystemControlForegroundBaseHighBrush" />
+    <StaticResource x:Key="SplitButtonForegroundPointerOver" ResourceKey="SystemControlHighlightBaseHighBrush" />
+    <StaticResource x:Key="SplitButtonForegroundPressed" ResourceKey="SystemControlHighlightBaseHighBrush" />
+    <StaticResource x:Key="SplitButtonForegroundDisabled" ResourceKey="SystemControlDisabledBaseMediumLowBrush" />
+    <StaticResource x:Key="SplitButtonForegroundChecked" ResourceKey="SystemControlHighlightAltChromeWhiteBrush" />
+    <StaticResource x:Key="SplitButtonForegroundCheckedPointerOver" ResourceKey="SystemControlHighlightAltChromeWhiteBrush" />
+    <StaticResource x:Key="SplitButtonForegroundCheckedPressed" ResourceKey="SystemControlHighlightAltChromeWhiteBrush" />
+    <StaticResource x:Key="SplitButtonForegroundCheckedDisabled" ResourceKey="SystemControlDisabledBaseMediumLowBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrush" ResourceKey="SystemControlForegroundTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushPointerOver" ResourceKey="SystemControlForegroundTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushPressed" ResourceKey="SystemControlHighlightTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushDisabled" ResourceKey="SystemControlDisabledTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushChecked" ResourceKey="SystemControlHighlightAltTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushCheckedPointerOver" ResourceKey="SystemControlHighlightAltTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushCheckedPressed" ResourceKey="SystemControlHighlightAltTransparentBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushCheckedDisabled" ResourceKey="SystemControlDisabledTransparentBrush" />
+    <Thickness x:Key="SplitButtonBorderThemeThickness">1</Thickness>
+
     <!-- Resources for SplitView.xaml -->
     <StaticResource x:Key="SplitViewLightDismissOverlayBackground" ResourceKey="SystemControlPageBackgroundMediumAltMediumBrush" />
   
diff --git a/src/Avalonia.Themes.Fluent/Controls/FluentControls.xaml b/src/Avalonia.Themes.Fluent/Controls/FluentControls.xaml
index 51836255ef..065278521e 100644
--- a/src/Avalonia.Themes.Fluent/Controls/FluentControls.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/FluentControls.xaml
@@ -56,6 +56,7 @@
   <StyleInclude Source="avares://Avalonia.Themes.Fluent/Controls/NotificationCard.xaml"/>
   <StyleInclude Source="avares://Avalonia.Themes.Fluent/Controls/NativeMenuBar.xaml"/>
   <StyleInclude Source="avares://Avalonia.Themes.Fluent/Controls/ToggleSwitch.xaml"/>
+  <StyleInclude Source="avares://Avalonia.Themes.Fluent/Controls/SplitButton.xaml" />
   <StyleInclude Source="avares://Avalonia.Themes.Fluent/Controls/SplitView.xaml"/>
   <StyleInclude Source="avares://Avalonia.Themes.Fluent/Controls/DatePicker.xaml"/>  
   <StyleInclude Source="avares://Avalonia.Themes.Fluent/Controls/TimePicker.xaml"/>  
diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
new file mode 100644
index 0000000000..1c20cd329f
--- /dev/null
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -0,0 +1,370 @@
+<Styles xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        x:CompileBindings="True">
+  <Design.PreviewWith>
+  </Design.PreviewWith>
+
+  <Styles.Resources>
+    <x:Double x:Key="SplitButtonPrimaryButtonSize">32</x:Double>
+    <x:Double x:Key="SplitButtonSecondaryButtonSize">32</x:Double>
+  </Styles.Resources>
+
+  <Style Selector="SplitButton">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForeground}" />
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrush}" />
+    <Setter Property="BorderThickness" Value="{DynamicResource SplitButtonBorderThemeThickness}" />
+    <Setter Property="HorizontalAlignment" Value="Left" />
+    <Setter Property="VerticalAlignment" Value="Center" />
+    <!--<Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}" />
+    <Setter Property="FontWeight" Value="Normal" />
+    <Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}" />
+    <Setter Property="UseSystemFocusVisuals" Value="True" />
+    <Setter Property="FocusVisualMargin" Value="-3" />-->
+    <Setter Property="KeyboardNavigation.IsTabStop" Value="True" />
+    <Setter Property="Padding" Value="{DynamicResource ButtonPadding}" />
+    <Setter Property="CornerRadius" Value="{DynamicResource ControlCornerRadius}" />
+    <Setter Property="Template">
+      <Setter.Value>
+        <ControlTemplate>
+          <!-- A Border was added here since Avalonia does not support Background/Border/CornerRadius on Grid directly -->
+          <!-- ClipToBounds added as a temporary work-around for: https://github.com/AvaloniaUI/Avalonia/issues/2105 -->
+          <Border Background="Transparent"
+                  CornerRadius="{TemplateBinding CornerRadius}"
+                  ClipToBounds="True">
+            <Border.Styles>
+              <!-- Override the style of the inner buttons so that they don't affect background/foreground/border colors -->
+              <Style Selector="Button">
+                <Setter Property="Foreground" Value="{DynamicResource SplitButtonForeground}" />
+                <Setter Property="BorderBrush" Value="Transparent" />
+                <Setter Property="BorderThickness" Value="{DynamicResource SplitButtonBorderThemeThickness}" />
+                <Setter Property="HorizontalAlignment" Value="Left" />
+                <Setter Property="VerticalAlignment" Value="Center" />
+                <!--<Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}" />
+                <Setter Property="FontWeight" Value="Normal" />
+                <Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}" />
+                <Setter Property="UseSystemFocusVisuals" Value="{StaticResource UseSystemFocusVisuals}" />
+                <Setter Property="FocusVisualMargin" Value="-3" />-->
+                <Setter Property="Template">
+                  <ControlTemplate>
+                    <!-- Switched from Grid to Border to optimize and support Foreground/Background properties -->
+                    <Border x:Name="RootBorder"
+                            Background="Transparent">
+                      <ContentPresenter x:Name="ContentPresenter"
+                                        BorderBrush="{TemplateBinding BorderBrush}"
+                                        BorderThickness="{TemplateBinding BorderThickness}"
+                                        Content="{TemplateBinding Content}"
+                                        ContentTemplate="{TemplateBinding ContentTemplate}"
+                                        Padding="{TemplateBinding Padding}"
+                                        HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                                        VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" />
+                    </Border>
+                  </ControlTemplate>
+                </Setter>
+              </Style>
+              <Style Selector="Button:disabled">
+                <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundDisabled}" />
+                <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundDisabled}" />
+              </Style>
+            </Border.Styles>
+            <Grid>
+              
+              <Grid.ColumnDefinitions>
+                <ColumnDefinition Width="*"
+                                  MinWidth="{DynamicResource SplitButtonPrimaryButtonSize}" />
+                <ColumnDefinition Width="1" />
+                <ColumnDefinition Width="{DynamicResource SplitButtonSecondaryButtonSize}" />
+              </Grid.ColumnDefinitions>
+
+              <!-- Changed from Grid to Rectangle since Avalonia does not support Background on Grid directly -->
+              <Rectangle x:Name="PrimaryBackgroundRectangle"
+                         Fill="{TemplateBinding Background}" />
+
+              <Rectangle x:Name="SecondaryBackgroundRectangle"
+                         Fill="{TemplateBinding Background}"
+                         Grid.Column="2" />
+
+              <!-- Changed from Grid to Border to support Background/Border/CornerRadius properties -->
+              <Border x:Name="Border"
+                      Grid.ColumnSpan="3"
+                      BorderBrush="{TemplateBinding BorderBrush}"
+                      BorderThickness="{TemplateBinding BorderThickness}"
+                      CornerRadius="{TemplateBinding CornerRadius}" />
+
+              <Button x:Name="PART_PrimaryButton"
+                      Grid.Column="0"
+                      Foreground="{TemplateBinding Foreground}"
+                      Background="{TemplateBinding Background}"
+                      BorderThickness="{TemplateBinding BorderThickness}"
+                      BorderBrush="Transparent"
+                      Content="{TemplateBinding Content}"
+                      ContentTemplate="{TemplateBinding ContentTemplate}"
+                      Command="{TemplateBinding Command}"
+                      CommandParameter="{TemplateBinding CommandParameter}"
+                      FontFamily="{TemplateBinding FontFamily}"
+                      FontSize="{TemplateBinding FontSize}"
+                      FontWeight="{TemplateBinding FontWeight}"
+                      HorizontalAlignment="Stretch"
+                      VerticalAlignment="Stretch"
+                      HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                      VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
+                      Padding="{TemplateBinding Padding}"
+                      KeyboardNavigation.IsTabStop="False" />
+
+              <Button x:Name="PART_SecondaryButton"
+                      Grid.Column="2"
+                      Foreground="{TemplateBinding Foreground}"
+                      Background="{TemplateBinding Background}"
+                      BorderThickness="{TemplateBinding BorderThickness}"
+                      BorderBrush="Transparent"
+                      HorizontalContentAlignment="Center"
+                      VerticalContentAlignment="Center"
+                      HorizontalAlignment="Stretch"
+                      VerticalAlignment="Stretch"
+                      KeyboardNavigation.IsTabStop="False">
+                <Button.Content>
+                  <!-- TextBlock converted to a Path and placed within Viewbox -->
+                  <Viewbox UseLayoutRounding="False"
+                           IsHitTestVisible="False"
+                           Height="12"
+                           Width="12">
+                    <Path x:Name="DropDownGlyphPath"
+                          VerticalAlignment="Center"
+                          HorizontalAlignment="Right"
+                          Fill="{TemplateBinding Foreground}"
+                          Data="M1939 486L2029 576L1024 1581L19 576L109 486L1024 1401L1939 486Z"
+                          Stretch="Uniform" />
+                  </Viewbox>
+                </Button.Content>
+              </Button>
+            </Grid>
+          </Border>
+        </ControlTemplate>
+      </Setter.Value>
+    </Setter>
+  </Style>
+
+  <!-- Disabled State -->
+  <Style Selector="SplitButton:disabled /template/ Border#Border">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushDisabled}" />
+  </Style>
+  <Style Selector="SplitButton:disabled /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundDisabled}" />
+  </Style>
+
+  <!-- FlyoutOpen State -->
+  <Style Selector="SplitButton:flyoutOpen /template/ Rectangle#PrimaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:flyoutOpen /template/ Rectangle#SecondaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:flyoutOpen /template/ Border#Border">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+  </Style>
+  <Style Selector="SplitButton:flyoutOpen /template/ Button#PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:flyoutOpen /template/ Button#SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+
+  <!-- TouchPressed State -->
+  <Style Selector="SplitButton:touchPressed /template/ Rectangle#PrimaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:touchPressed /template/ Rectangle#SecondaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:touchPressed /template/ Border#Border">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+  </Style>
+  <Style Selector="SplitButton:touchPressed /template/ Button#PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:touchPressed /template/ Button#SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+
+  <!-- PrimaryPointerOver State -->
+  <Style Selector="SplitButton:primaryPointerOver /template/ Rectangle#PrimaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:primaryPointerOver /template/ Button#PrimaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:primaryPointerOver /template/ Rectangle#SecondaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackground}" />
+  </Style>
+
+  <!-- PrimaryPressed State -->
+  <Style Selector="SplitButton:primaryPressed /template/ Rectangle#PrimaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:primaryPressed /template/ Button#PrimaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:primaryPressed /template/ Rectangle#SecondaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackground}" />
+  </Style>
+
+  <!-- SecondaryPointerOver State -->
+  <Style Selector="SplitButton:secondaryPointerOver /template/ Rectangle#PrimaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackground}" />
+  </Style>
+  <Style Selector="SplitButton:secondaryPointerOver /template/ Rectangle#SecondaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:secondaryPointerOver /template/ Button#SecondaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
+  </Style>
+
+  <!-- SecondaryPressed State -->
+  <Style Selector="SplitButton:secondaryPressed /template/ Rectangle#PrimaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackground}" />
+  </Style>
+  <Style Selector="SplitButton:secondaryPressed /template/ Rectangle#SecondaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:secondaryPressed /template/ Button#SecondaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+
+  <!-- Checked State -->
+  <!--<VisualState x:Name="Checked">
+    <VisualState.Setters>
+      <Setter Target="PrimaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundChecked}" />
+      <Setter Target="SecondaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundChecked}" />
+      <Setter Target="Border.BorderBrush"
+              Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+      <Setter Target="PrimaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundChecked}" />
+      <Setter Target="SecondaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundChecked}" />
+    </VisualState.Setters>
+  </VisualState>-->
+
+  <!-- CheckedFlyoutOpen State -->
+  <!--<VisualState x:Name="CheckedFlyoutOpen">
+    <VisualState.Setters>
+      <Setter Target="PrimaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+      <Setter Target="SecondaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+      <Setter Target="Border.BorderBrush"
+              Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+      <Setter Target="PrimaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+      <Setter Target="SecondaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+    </VisualState.Setters>
+  </VisualState>-->
+
+  <!-- CheckedTouchPressed State -->
+  <!--<VisualState x:Name="CheckedTouchPressed">
+    <VisualState.Setters>
+      <Setter Target="PrimaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+      <Setter Target="SecondaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+      <Setter Target="Border.BorderBrush"
+              Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+      <Setter Target="PrimaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+      <Setter Target="SecondaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+    </VisualState.Setters>
+  </VisualState>-->
+
+  <!-- CheckedPrimaryPointerOver State -->
+  <!--<VisualState x:Name="CheckedPrimaryPointerOver">
+    <VisualState.Setters>
+      <Setter Target="Border.BorderBrush"
+              Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+      <Setter Target="PrimaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
+      <Setter Target="PrimaryButton.BorderBrush"
+              Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
+      <Setter Target="PrimaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
+      <Setter Target="SecondaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundChecked}" />
+      <Setter Target="SecondaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundChecked}" />
+    </VisualState.Setters>
+  </VisualState>-->
+
+  <!-- CheckedPrimaryPressed State -->
+  <!--<VisualState x:Name="CheckedPrimaryPressed">
+    <VisualState.Setters>
+      <Setter Target="Border.BorderBrush"
+              Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+      <Setter Target="PrimaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+      <Setter Target="PrimaryButton.BorderBrush"
+              Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+      <Setter Target="PrimaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+      <Setter Target="SecondaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundChecked}" />
+      <Setter Target="SecondaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundChecked}" />
+    </VisualState.Setters>
+  </VisualState>-->
+
+  <!-- CheckedSecondaryPointerOver State -->
+  <!--<VisualState x:Name="CheckedSecondaryPointerOver">
+    <VisualState.Setters>
+      <Setter Target="Border.BorderBrush"
+              Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+      <Setter Target="PrimaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundChecked}" />
+      <Setter Target="PrimaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundChecked}" />
+      <Setter Target="SecondaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
+      <Setter Target="SecondaryButton.BorderBrush"
+              Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
+      <Setter Target="SecondaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
+    </VisualState.Setters>
+  </VisualState>-->
+
+  <!-- CheckedSecondaryPressed State -->
+  <!--<VisualState x:Name="CheckedSecondaryPressed">
+    <VisualState.Setters>
+      <Setter Target="Border.BorderBrush"
+              Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+      <Setter Target="PrimaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundChecked}" />
+      <Setter Target="PrimaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundChecked}" />
+      <Setter Target="SecondaryBackgroundRectangle.Fill"
+              Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+      <Setter Target="SecondaryButton.BorderBrush"
+              Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+      <Setter Target="SecondaryButton.Foreground"
+              Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+    </VisualState.Setters>
+  </VisualState>-->
+
+  <!--VisualStateGroup x:Name="SecondaryButtonPlacementStates">
+    <VisualState x:Name="SecondaryButtonRight" />
+
+    <VisualState x:Name="SecondaryButtonSpan">
+      <VisualState.Setters>
+        <Setter Target="SecondaryButton.(Grid.Column)"
+                Value="0" />
+        <Setter Target="SecondaryButton.(Grid.ColumnSpan)"
+                Value="3" />
+      </VisualState.Setters>
+    </VisualState>
+  </VisualStateGroup-->
+
+</Styles>

From b3049cf66468dcc1c954189a7d0ce82c950e8682 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Mon, 24 Jan 2022 14:22:58 -0500
Subject: [PATCH 05/48] Add missing space

---
 src/Avalonia.Themes.Fluent/Controls/ComboBox.xaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Avalonia.Themes.Fluent/Controls/ComboBox.xaml b/src/Avalonia.Themes.Fluent/Controls/ComboBox.xaml
index f07fc6f2e0..857d70084c 100644
--- a/src/Avalonia.Themes.Fluent/Controls/ComboBox.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/ComboBox.xaml
@@ -150,7 +150,7 @@
     </Setter>
   </Style>
 
-  <!--  NormalState  -->
+  <!--  Normal State  -->
   <Style Selector="ComboBox /template/ TextBlock#PlaceholderTextBlock">
     <Setter Property="Foreground" Value="{DynamicResource ComboBoxPlaceHolderForeground}" />
   </Style>

From 7a9dffa5867a3c106298379f066c0ee3c521607c Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Mon, 24 Jan 2022 14:23:18 -0500
Subject: [PATCH 06/48] Fix ICommandSource comments

---
 src/Avalonia.Input/ICommandSource.cs | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/Avalonia.Input/ICommandSource.cs b/src/Avalonia.Input/ICommandSource.cs
index 410b3a2e47..a6b5189440 100644
--- a/src/Avalonia.Input/ICommandSource.cs
+++ b/src/Avalonia.Input/ICommandSource.cs
@@ -20,12 +20,11 @@ namespace Avalonia.Input
         /// </summary>
         object? CommandParameter { get; }
 
-
         /// <summary>
-        /// Bor the behavior CanExecuteChanged
+        /// Called for the CanExecuteChanged event when changes are detected.
         /// </summary>
-        /// <param name="sender"></param>
-        /// <param name="e"></param>
+        /// <param name="sender">The event sender.</param>
+        /// <param name="e">The event args.</param>
         void CanExecuteChanged(object sender, System.EventArgs e);
 
         /// <summary>

From a6f158274566f8bd3f1c5f7cfa90ddda2c438232 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Mon, 24 Jan 2022 14:23:40 -0500
Subject: [PATCH 07/48] Add sample SplitButtons to the ControlCatalog

---
 .../ControlCatalog/Pages/SplitButtonPage.xaml | 31 +++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/samples/ControlCatalog/Pages/SplitButtonPage.xaml b/samples/ControlCatalog/Pages/SplitButtonPage.xaml
index a2e12a1528..2ada3bf3f4 100644
--- a/samples/ControlCatalog/Pages/SplitButtonPage.xaml
+++ b/samples/ControlCatalog/Pages/SplitButtonPage.xaml
@@ -2,5 +2,36 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              x:Class="ControlCatalog.Pages.SplitButtonPage">
   <StackPanel Orientation="Vertical" Spacing="4">
+    <SplitButton>
+      <TextBlock Text="Content" />
+      <SplitButton.Flyout>
+        <MenuFlyout>
+          <MenuItem Header="Item 1">
+            <MenuItem Header="Subitem 1" />
+            <MenuItem Header="Subitem 2" />
+            <MenuItem Header="Subitem 3" />
+          </MenuItem>
+          <MenuItem Header="Item 2"
+                    InputGesture="Ctrl+A" />
+          <MenuItem Header="Item 3" />
+        </MenuFlyout>
+      </SplitButton.Flyout>
+    </SplitButton>
+    <SplitButton
+      IsEnabled="False">
+      <TextBlock Text="Content" />
+      <SplitButton.Flyout>
+        <MenuFlyout>
+          <MenuItem Header="Item 1">
+            <MenuItem Header="Subitem 1" />
+            <MenuItem Header="Subitem 2" />
+            <MenuItem Header="Subitem 3" />
+          </MenuItem>
+          <MenuItem Header="Item 2"
+                    InputGesture="Ctrl+A" />
+          <MenuItem Header="Item 3" />
+        </MenuFlyout>
+      </SplitButton.Flyout>
+    </SplitButton>
   </StackPanel>
 </UserControl>

From 4322e216c4947b394e38d4b5d0a7b32e54f212ec Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Mon, 24 Jan 2022 14:56:30 -0500
Subject: [PATCH 08/48] Remove code that shouldn't be there

---
 src/Avalonia.Controls/SplitButton/SplitButton.cs | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index 4af8b44629..a6a3112d05 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -1,7 +1,6 @@
 using System;
 using System.Reactive.Disposables;
 using System.Windows.Input;
-using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -400,8 +399,6 @@ namespace Avalonia.Controls
             {
                 _primaryButton.Click += PrimaryButton_Click;
 
-                _primaryButton.GetPropertyChangedObservable(Button.IsPressedProperty);
-
                 _buttonPropertyChangedDisposable.Add(_primaryButton.GetPropertyChangedObservable(Button.IsPressedProperty).Subscribe(Button_VisualPropertyChanged));
                 _buttonPropertyChangedDisposable.Add(_primaryButton.GetPropertyChangedObservable(Button.IsPointerOverProperty).Subscribe(Button_VisualPropertyChanged));
 

From 29865672e24cd265ae8a53a2f2e2f0fad010286d Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Mon, 24 Jan 2022 23:46:23 -0500
Subject: [PATCH 09/48] Add ToggleSplitButton

---
 .../ControlCatalog/Pages/SplitButtonPage.xaml |  57 ++---
 .../SplitButton/SplitButton.cs                | 145 ++++++++----
 .../SplitButton/SplitButtonClickEventArgs.cs  |  25 --
 .../SplitButton/ToggleSplitButton.cs          | 147 ++++++++++++
 .../Controls/SplitButton.xaml                 | 215 +++++++++---------
 5 files changed, 390 insertions(+), 199 deletions(-)
 delete mode 100644 src/Avalonia.Controls/SplitButton/SplitButtonClickEventArgs.cs
 create mode 100644 src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs

diff --git a/samples/ControlCatalog/Pages/SplitButtonPage.xaml b/samples/ControlCatalog/Pages/SplitButtonPage.xaml
index 2ada3bf3f4..e530920dab 100644
--- a/samples/ControlCatalog/Pages/SplitButtonPage.xaml
+++ b/samples/ControlCatalog/Pages/SplitButtonPage.xaml
@@ -1,37 +1,40 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              x:Class="ControlCatalog.Pages.SplitButtonPage">
+
+  <UserControl.Resources>
+    <MenuFlyout x:Key="SharedMenuFlyout"
+                Placement="Bottom">
+      <MenuItem Header="Item 1">
+        <MenuItem Header="Subitem 1" />
+        <MenuItem Header="Subitem 2" />
+        <MenuItem Header="Subitem 3" />
+      </MenuItem>
+      <MenuItem Header="Item 2"
+                InputGesture="Ctrl+A" />
+      <MenuItem Header="Item 3" />
+    </MenuFlyout>
+  </UserControl.Resources>
+
   <StackPanel Orientation="Vertical" Spacing="4">
-    <SplitButton>
+    <SplitButton Flyout="{StaticResource SharedMenuFlyout}">
       <TextBlock Text="Content" />
-      <SplitButton.Flyout>
-        <MenuFlyout>
-          <MenuItem Header="Item 1">
-            <MenuItem Header="Subitem 1" />
-            <MenuItem Header="Subitem 2" />
-            <MenuItem Header="Subitem 3" />
-          </MenuItem>
-          <MenuItem Header="Item 2"
-                    InputGesture="Ctrl+A" />
-          <MenuItem Header="Item 3" />
-        </MenuFlyout>
-      </SplitButton.Flyout>
     </SplitButton>
-    <SplitButton
-      IsEnabled="False">
+    <SplitButton IsEnabled="False"
+                 Flyout="{StaticResource SharedMenuFlyout}">
       <TextBlock Text="Content" />
-      <SplitButton.Flyout>
-        <MenuFlyout>
-          <MenuItem Header="Item 1">
-            <MenuItem Header="Subitem 1" />
-            <MenuItem Header="Subitem 2" />
-            <MenuItem Header="Subitem 3" />
-          </MenuItem>
-          <MenuItem Header="Item 2"
-                    InputGesture="Ctrl+A" />
-          <MenuItem Header="Item 3" />
-        </MenuFlyout>
-      </SplitButton.Flyout>
     </SplitButton>
+    <ToggleSplitButton Flyout="{StaticResource SharedMenuFlyout}">
+      <TextBlock Text="Content" />
+    </ToggleSplitButton>
+    <ToggleSplitButton IsChecked="True"
+                       Flyout="{StaticResource SharedMenuFlyout}">
+      <TextBlock Text="Content" />
+    </ToggleSplitButton>
+    <ToggleSplitButton IsChecked="True"
+                       IsEnabled="False"
+                       Flyout="{StaticResource SharedMenuFlyout}">
+      <TextBlock Text="Content" />
+    </ToggleSplitButton>
   </StackPanel>
 </UserControl>
diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index a6a3112d05..d30217ae4c 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Reactive.Disposables;
 using System.Windows.Input;
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -9,16 +10,32 @@ using Avalonia.LogicalTree;
 namespace Avalonia.Controls
 {
     /// <summary>
-    /// A button with primary and secondary parts that can each be invoked separately.
-    /// The primary part behaves like a button and the secondary part opens a flyout.
+    /// A button with primary and secondary parts that can each be pressed separately.
+    /// The primary part behaves like a <see cref="Button"/> and the secondary part opens a flyout.
     /// </summary>
-    //[PseudoClasses(":pressed")]
+    [PseudoClasses(
+        ":disabled",
+        ":secondaryButtonRight",
+        ":secondaryButtonSpan",
+        ":checkedFlyoutOpen",
+        ":flyoutOpen",
+        ":checkedTouchPressed",
+        ":checked",
+        ":checkedPrimaryPressed",
+        ":checkedPrimaryPointerOver",
+        ":checkedSecondaryPressed",
+        ":checkedSecondaryPointerOver",
+        ":touchPressed",
+        ":primaryPressed",
+        ":primaryPointerOver",
+        ":secondaryPressed",
+        ":secondaryPointerOver")]
     public class SplitButton : ContentControl, ICommandSource
     {
         /// <summary>
         /// Raised when the user presses the primary part of the <see cref="SplitButton"/>.
         /// </summary>
-        public event EventHandler<SplitButtonClickEventArgs> Click
+        public event EventHandler<RoutedEventArgs> Click
         {
             add => AddHandler(ClickEvent, value);
             remove => RemoveHandler(ClickEvent, value);
@@ -27,8 +44,8 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="Click"/> event.
         /// </summary>
-        public static readonly RoutedEvent<SplitButtonClickEventArgs> ClickEvent =
-            RoutedEvent.Register<SplitButton, SplitButtonClickEventArgs>(
+        public static readonly RoutedEvent<RoutedEventArgs> ClickEvent =
+            RoutedEvent.Register<SplitButton, RoutedEventArgs>(
                 nameof(Click),
                 RoutingStrategies.Bubble);
 
@@ -61,11 +78,12 @@ namespace Avalonia.Controls
         private Button _primaryButton   = null;
         private Button _secondaryButton = null;
 
-        private bool        _commandCanExecute = true;
-        protected bool      _hasLoaded         = false;
-        private bool        _isFlyoutOpen      = false;
-        private bool        _isKeyDown         = false;
-        private PointerType _lastPointerType   = PointerType.Mouse;
+        private bool        _commandCanExecute       = true;
+        protected bool      _hasLoaded               = false;
+        private bool        _isAttachedToLogicalTree = false;
+        private bool        _isFlyoutOpen            = false;
+        private bool        _isKeyDown               = false;
+        private PointerType _lastPointerType         = PointerType.Mouse;
 
         private CompositeDisposable _buttonPropertyChangedDisposable;
         private IDisposable         _flyoutPropertyChangedDisposable;
@@ -116,6 +134,19 @@ namespace Avalonia.Controls
             set => SetValue(FlyoutProperty, value);
         }
 
+        /// <summary>
+        /// Gets a value indicating whether the button is currently checked.
+        /// </summary>
+        /// <remarks>
+        /// This property exists only for the derived <see cref="ToggleSplitButton"/> and is
+        /// unused (set to false) within <see cref="SplitButton"/>. Doing this allows the
+        /// two controls to share a default style.
+        /// </remarks>
+        internal virtual bool InternalIsChecked => false;
+
+        /// <inheritdoc/>
+        protected override bool IsEnabledCore => base.IsEnabledCore && _commandCanExecute;
+
         ////////////////////////////////////////////////////////////////////////
         // 
         // Methods
@@ -134,17 +165,12 @@ namespace Avalonia.Controls
             }
         }
 
-        /// <inheritdoc/>
-        protected override bool IsEnabledCore => base.IsEnabledCore && _commandCanExecute;
-
         /// <summary>
         /// Updates the visual state of the control by applying latest PseudoClasses.
         /// </summary>
-        private void UpdatePseudoClasses()
+        protected void UpdatePseudoClasses()
         {
-            bool internalIsChecked = false;
-
-            string pcNormal   = ":normal";
+            string pcNormal   = ":normal"; // Not supported in XAML style
             string pcDisabled = ":disabled";
 
             string pcSecondaryButtonRight = ":secondaryButtonRight";
@@ -189,7 +215,7 @@ namespace Avalonia.Controls
             {
                 if (_isFlyoutOpen)
                 {
-                    if (internalIsChecked)
+                    if (InternalIsChecked)
                     {
                         SetExclusivePseudoClass(pcCheckedFlyoutOpen);
                     }
@@ -199,7 +225,7 @@ namespace Avalonia.Controls
                     }
                 }
                 // SplitButton and ToggleSplitButton share a template -- this section is driving the checked states for ToggleSplitButton.
-                else if (internalIsChecked)
+                else if (InternalIsChecked)
                 {
                     if (_lastPointerType == PointerType.Touch || _isKeyDown)
                     {
@@ -273,23 +299,23 @@ namespace Avalonia.Controls
             // This more closely matches the VisualStateManager of WinUI where the default style originated
             void SetExclusivePseudoClass(string pseudoClass = "")
             {
-                PseudoClasses.Set(pcNormal, pseudoClass == pcNormal);
+                PseudoClasses.Set(pcNormal,   pseudoClass == pcNormal);
                 PseudoClasses.Set(pcDisabled, pseudoClass == pcDisabled);
 
                 PseudoClasses.Set(pcCheckedFlyoutOpen, pseudoClass == pcCheckedFlyoutOpen);
-                PseudoClasses.Set(pcFlyoutOpen, pseudoClass == pcFlyoutOpen);
+                PseudoClasses.Set(pcFlyoutOpen,        pseudoClass == pcFlyoutOpen);
 
-                PseudoClasses.Set(pcCheckedTouchPressed, pseudoClass == pcCheckedTouchPressed);
-                PseudoClasses.Set(pcChecked, pseudoClass == pcChecked);
-                PseudoClasses.Set(pcCheckedPrimaryPressed, pseudoClass == pcCheckedPrimaryPressed);
-                PseudoClasses.Set(pcCheckedPrimaryPointerOver, pseudoClass == pcCheckedPrimaryPointerOver);
-                PseudoClasses.Set(pcCheckedSecondaryPressed, pseudoClass == pcCheckedSecondaryPressed);
+                PseudoClasses.Set(pcCheckedTouchPressed,         pseudoClass == pcCheckedTouchPressed);
+                PseudoClasses.Set(pcChecked,                     pseudoClass == pcChecked);
+                PseudoClasses.Set(pcCheckedPrimaryPressed,       pseudoClass == pcCheckedPrimaryPressed);
+                PseudoClasses.Set(pcCheckedPrimaryPointerOver,   pseudoClass == pcCheckedPrimaryPointerOver);
+                PseudoClasses.Set(pcCheckedSecondaryPressed,     pseudoClass == pcCheckedSecondaryPressed);
                 PseudoClasses.Set(pcCheckedSecondaryPointerOver, pseudoClass == pcCheckedSecondaryPointerOver);
 
-                PseudoClasses.Set(pcTouchPressed, pseudoClass == pcTouchPressed);
-                PseudoClasses.Set(pcPrimaryPressed, pseudoClass == pcPrimaryPressed);
-                PseudoClasses.Set(pcPrimaryPointerOver, pseudoClass == pcPrimaryPointerOver);
-                PseudoClasses.Set(pcSecondaryPressed, pseudoClass == pcSecondaryPressed);
+                PseudoClasses.Set(pcTouchPressed,         pseudoClass == pcTouchPressed);
+                PseudoClasses.Set(pcPrimaryPressed,       pseudoClass == pcPrimaryPressed);
+                PseudoClasses.Set(pcPrimaryPointerOver,   pseudoClass == pcPrimaryPointerOver);
+                PseudoClasses.Set(pcSecondaryPressed,     pseudoClass == pcSecondaryPressed);
                 PseudoClasses.Set(pcSecondaryPointerOver, pseudoClass == pcSecondaryPointerOver);
             }
         }
@@ -297,7 +323,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Opens the secondary button's flyout.
         /// </summary>
-        private void OpenFlyout()
+        protected void OpenFlyout()
         {
             if (Flyout != null)
             {
@@ -308,7 +334,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Closes the secondary button's flyout.
         /// </summary>
-        private void CloseFlyout()
+        protected void CloseFlyout()
         {
             if (Flyout != null)
             {
@@ -447,26 +473,63 @@ namespace Avalonia.Controls
         protected override void OnAttachedToLogicalTree(LogicalTreeAttachmentEventArgs e)
         {
             base.OnAttachedToLogicalTree(e);
+
+            if (Command != null)
+            {
+                Command.CanExecuteChanged += CanExecuteChanged;
+                CanExecuteChanged(this, EventArgs.Empty);
+            }
+
+            _isAttachedToLogicalTree = true;
         }
 
         /// <inheritdoc/>
         protected override void OnDetachedFromLogicalTree(LogicalTreeAttachmentEventArgs e)
         {
             base.OnDetachedFromLogicalTree(e);
+
+            if (Command != null)
+            {
+                Command.CanExecuteChanged -= CanExecuteChanged;
+            }
+
+            _isAttachedToLogicalTree = false;
         }
 
         /// <inheritdoc/>
-        protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> changedEventArgs)
+        protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> e)
         {
-            if (changedEventArgs.Property == FlyoutProperty)
+            if (e.Property == CommandProperty)
+            {
+                if (_isAttachedToLogicalTree)
+                {
+                    // Must unregister events here while a reference to the old command still exists
+                    if (e.OldValue is ICommand oldCommand)
+                    {
+                        oldCommand.CanExecuteChanged -= CanExecuteChanged;
+                    }
+
+                    if (e.NewValue is ICommand newCommand)
+                    {
+                        newCommand.CanExecuteChanged += CanExecuteChanged;
+                    }
+                }
+
+                CanExecuteChanged(this, EventArgs.Empty);
+            }
+            else if (e.Property == CommandParameterProperty)
+            {
+                CanExecuteChanged(this, EventArgs.Empty);
+            }
+            else if (e.Property == FlyoutProperty)
             {
-                // Must unregister events here while a ref to the old flyout still exists
-                if (changedEventArgs.OldValue.GetValueOrDefault() is FlyoutBase oldFlyout)
+                // Must unregister events here while a reference to the old flyout still exists
+                if (e.OldValue.GetValueOrDefault() is FlyoutBase oldFlyout)
                 {
                     UnregisterFlyoutEvents(oldFlyout);
                 }
 
-                if (changedEventArgs.NewValue.GetValueOrDefault() is FlyoutBase newFlyout)
+                if (e.NewValue.GetValueOrDefault() is FlyoutBase newFlyout)
                 {
                     RegisterFlyoutEvents(newFlyout);
                 }
@@ -474,7 +537,7 @@ namespace Avalonia.Controls
                 UpdatePseudoClasses();
             }
 
-            base.OnPropertyChanged(changedEventArgs);
+            base.OnPropertyChanged(e);
         }
 
         /// <inheritdoc/>
@@ -526,7 +589,7 @@ namespace Avalonia.Controls
         }
 
         /// <summary>
-        /// Invokes the <see cref="Click"/> when the primary button part is clicked.
+        /// Invokes the <see cref="Click"/> event when the primary button part is clicked.
         /// </summary>
         /// <param name="e">The event args from the internal Click event.</param>
         protected virtual void OnClickPrimary(RoutedEventArgs e)
@@ -534,7 +597,7 @@ namespace Avalonia.Controls
             // Note: It is not currently required to check enabled status; however, this is a failsafe
             if (IsEffectivelyEnabled)
             {
-                var eventArgs = new SplitButtonClickEventArgs(ClickEvent);
+                var eventArgs = new RoutedEventArgs(ClickEvent);
                 RaiseEvent(eventArgs);
 
                 if (!eventArgs.Handled && Command?.CanExecute(CommandParameter) == true)
diff --git a/src/Avalonia.Controls/SplitButton/SplitButtonClickEventArgs.cs b/src/Avalonia.Controls/SplitButton/SplitButtonClickEventArgs.cs
deleted file mode 100644
index 0359fb2f53..0000000000
--- a/src/Avalonia.Controls/SplitButton/SplitButtonClickEventArgs.cs
+++ /dev/null
@@ -1,25 +0,0 @@
-using Avalonia.Interactivity;
-
-namespace Avalonia.Controls
-{
-    /// <summary>
-    /// Provides event data for the <see cref="SplitButton.Click"/> event.
-    /// </summary>
-    public class SplitButtonClickEventArgs : RoutedEventArgs
-    {
-        public SplitButtonClickEventArgs()
-        {
-        }
-
-        public SplitButtonClickEventArgs(RoutedEvent? routedEvent)
-        {
-            RoutedEvent = routedEvent;
-        }
-
-        public SplitButtonClickEventArgs(RoutedEvent? routedEvent, IInteractive? source)
-        {
-            RoutedEvent = routedEvent;
-            Source = source;
-        }
-    }
-}
diff --git a/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs b/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
new file mode 100644
index 0000000000..c062f577de
--- /dev/null
+++ b/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
@@ -0,0 +1,147 @@
+using System;
+using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Primitives;
+using Avalonia.Interactivity;
+using Avalonia.Styling;
+
+namespace Avalonia.Controls
+{
+    /// <summary>
+    /// A button with primary and secondary parts that can each be pressed separately.
+    /// The primary part behaves like a <see cref="ToggleButton"/> with two states and
+    /// the secondary part opens a flyout.
+    /// </summary>
+    [PseudoClasses(
+        ":disabled",
+        ":secondaryButtonRight",
+        ":secondaryButtonSpan",
+        ":checkedFlyoutOpen",
+        ":flyoutOpen",
+        ":checkedTouchPressed",
+        ":checked",
+        ":checkedPrimaryPressed",
+        ":checkedPrimaryPointerOver",
+        ":checkedSecondaryPressed",
+        ":checkedSecondaryPointerOver",
+        ":touchPressed",
+        ":primaryPressed",
+        ":primaryPointerOver",
+        ":secondaryPressed",
+        ":secondaryPointerOver")]
+    public class ToggleSplitButton : SplitButton, IStyleable
+    {
+        /// <summary>
+        /// Raised when the <see cref="IsChecked"/> property value changes.
+        /// </summary>
+        public event EventHandler<RoutedEventArgs> IsCheckedChanged
+        {
+            add => AddHandler(IsCheckedChangedEvent, value);
+            remove => RemoveHandler(IsCheckedChangedEvent, value);
+        }
+
+        /// <summary>
+        /// Defines the <see cref="IsCheckedChanged"/> event.
+        /// </summary>
+        public static readonly RoutedEvent<RoutedEventArgs> IsCheckedChangedEvent =
+            RoutedEvent.Register<ToggleSplitButton, RoutedEventArgs>(
+                nameof(IsCheckedChanged),
+                RoutingStrategies.Bubble);
+
+        /// <summary>
+        /// Defines the <see cref="IsChecked"/> property.
+        /// </summary>
+        public static readonly StyledProperty<bool> IsCheckedProperty =
+            AvaloniaProperty.Register<ToggleSplitButton, bool>(
+                nameof(IsChecked));
+
+        ////////////////////////////////////////////////////////////////////////
+        // 
+        // Constructor / Destructors
+        //
+        ////////////////////////////////////////////////////////////////////////
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ToggleSplitButton"/> class.
+        /// </summary>
+        public ToggleSplitButton()
+        {
+        }
+
+        ////////////////////////////////////////////////////////////////////////
+        // 
+        // Properties
+        //
+        ////////////////////////////////////////////////////////////////////////
+
+        /// <summary>
+        /// Gets or sets a value indicating whether the <see cref="ToggleSplitButton"/> is checked.
+        /// </summary>
+        public bool IsChecked
+        {
+            get => GetValue(IsCheckedProperty);
+            set => SetValue(IsCheckedProperty, value);
+        }
+
+        /// <inheritdoc/>
+        internal override bool InternalIsChecked => IsChecked;
+
+        /// <inheritdoc/>
+        /// <remarks>
+        /// Both <see cref="ToggleSplitButton"/> and <see cref="SplitButton"/> share
+        /// the same exact default style.
+        /// </remarks>
+        Type IStyleable.StyleKey => typeof(SplitButton);
+
+        ////////////////////////////////////////////////////////////////////////
+        // 
+        // Methods
+        //
+        ////////////////////////////////////////////////////////////////////////
+
+        /// <summary>
+        /// Toggles the <see cref="IsChecked"/> property between true and false.
+        /// </summary>
+        protected void Toggle()
+        {
+            IsChecked = !IsChecked;
+        }
+
+        ////////////////////////////////////////////////////////////////////////
+        // 
+        // OnEvent Overridable Methods
+        //
+        ////////////////////////////////////////////////////////////////////////
+
+        /// <inheritdoc/>
+        protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> e)
+        {
+            if (e.Property == IsCheckedProperty)
+            {
+                OnIsCheckedChanged();
+            }
+        }
+
+        /// <summary>
+        /// Invokes the <see cref="IsCheckedChanged"/> event when the <see cref="IsChecked"/>
+        /// property changes.
+        /// </summary>
+        protected virtual void OnIsCheckedChanged()
+        {
+            if (_hasLoaded)
+            {
+                var eventArgs = new RoutedEventArgs(IsCheckedChangedEvent);
+                RaiseEvent(eventArgs);
+            }
+
+            UpdatePseudoClasses();
+        }
+
+        /// <inheritdoc/>
+        protected override void OnClickPrimary(RoutedEventArgs e)
+        {
+            Toggle();
+
+            base.OnClickPrimary(e);
+        }
+    }
+}
diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index 1c20cd329f..1b48f22a8c 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -235,124 +235,127 @@
   </Style>
 
   <!-- Checked State -->
-  <!--<VisualState x:Name="Checked">
-    <VisualState.Setters>
-      <Setter Target="PrimaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundChecked}" />
-      <Setter Target="SecondaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundChecked}" />
-      <Setter Target="Border.BorderBrush"
-              Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-      <Setter Target="PrimaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundChecked}" />
-      <Setter Target="SecondaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundChecked}" />
-    </VisualState.Setters>
-  </VisualState>-->
+  <Style Selector="SplitButton:checked /template/ Rectangle#PrimaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked /template/ Rectangle#SecondaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked /template/ Border#Border">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked /template/ Button#PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked /template/ Button#SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
 
   <!-- CheckedFlyoutOpen State -->
-  <!--<VisualState x:Name="CheckedFlyoutOpen">
-    <VisualState.Setters>
-      <Setter Target="PrimaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-      <Setter Target="SecondaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-      <Setter Target="Border.BorderBrush"
-              Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
-      <Setter Target="PrimaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-      <Setter Target="SecondaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-    </VisualState.Setters>
-  </VisualState>-->
+  <Style Selector="SplitButton:checkedFlyoutOpen /template/ Rectangle#PrimaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checkedFlyoutOpen /template/ Rectangle#SecondaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checkedFlyoutOpen /template/ Border#Border">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checkedFlyoutOpen /template/ Button#PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checkedFlyoutOpen /template/ Button#SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
 
   <!-- CheckedTouchPressed State -->
-  <!--<VisualState x:Name="CheckedTouchPressed">
-    <VisualState.Setters>
-      <Setter Target="PrimaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-      <Setter Target="SecondaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-      <Setter Target="Border.BorderBrush"
-              Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
-      <Setter Target="PrimaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-      <Setter Target="SecondaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-    </VisualState.Setters>
-  </VisualState>-->
+  <Style Selector="SplitButton:checkedTouchPressed /template/ Rectangle#PrimaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checkedTouchPressed /template/ Rectangle#SecondaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checkedTouchPressed /template/ Border#Border">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checkedTouchPressed /template/ Button#PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checkedTouchPressed /template/ Button#SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
 
   <!-- CheckedPrimaryPointerOver State -->
-  <!--<VisualState x:Name="CheckedPrimaryPointerOver">
-    <VisualState.Setters>
-      <Setter Target="Border.BorderBrush"
-              Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-      <Setter Target="PrimaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
-      <Setter Target="PrimaryButton.BorderBrush"
-              Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
-      <Setter Target="PrimaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
-      <Setter Target="SecondaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundChecked}" />
-      <Setter Target="SecondaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundChecked}" />
-    </VisualState.Setters>
-  </VisualState>-->
+  <Style Selector="SplitButton:checkedPrimaryPointerOver /template/ Border#Border">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checkedPrimaryPointerOver /template/ Rectangle#PrimaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:checkedPrimaryPointerOver /template/ Rectangle#SecondaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checkedPrimaryPointerOver /template/ Button#PrimaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:checkedPrimaryPointerOver /template/ Button#SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
 
   <!-- CheckedPrimaryPressed State -->
-  <!--<VisualState x:Name="CheckedPrimaryPressed">
-    <VisualState.Setters>
-      <Setter Target="Border.BorderBrush"
-              Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-      <Setter Target="PrimaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-      <Setter Target="PrimaryButton.BorderBrush"
-              Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
-      <Setter Target="PrimaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-      <Setter Target="SecondaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundChecked}" />
-      <Setter Target="SecondaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundChecked}" />
-    </VisualState.Setters>
-  </VisualState>-->
+  <Style Selector="SplitButton:checkedPrimaryPressed /template/ Border#Border">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checkedPrimaryPressed /template/ Rectangle#PrimaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checkedPrimaryPressed /template/ Rectangle#SecondaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checkedPrimaryPressed /template/ Button#PrimaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checkedPrimaryPressed /template/ Button#SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
 
   <!-- CheckedSecondaryPointerOver State -->
-  <!--<VisualState x:Name="CheckedSecondaryPointerOver">
-    <VisualState.Setters>
-      <Setter Target="Border.BorderBrush"
-              Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-      <Setter Target="PrimaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundChecked}" />
-      <Setter Target="PrimaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundChecked}" />
-      <Setter Target="SecondaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
-      <Setter Target="SecondaryButton.BorderBrush"
-              Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
-      <Setter Target="SecondaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
-    </VisualState.Setters>
-  </VisualState>-->
+  <Style Selector="SplitButton:checkedSecondaryPointerOver /template/ Border#Border">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checkedSecondaryPointerOver /template/ Rectangle#PrimaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checkedSecondaryPointerOver /template/ Rectangle#SecondaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:checkedSecondaryPointerOver /template/ Button#PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checkedSecondaryPointerOver /template/ Button#SecondaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
+  </Style>
 
   <!-- CheckedSecondaryPressed State -->
-  <!--<VisualState x:Name="CheckedSecondaryPressed">
-    <VisualState.Setters>
-      <Setter Target="Border.BorderBrush"
-              Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-      <Setter Target="PrimaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundChecked}" />
-      <Setter Target="PrimaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundChecked}" />
-      <Setter Target="SecondaryBackgroundRectangle.Fill"
-              Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-      <Setter Target="SecondaryButton.BorderBrush"
-              Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
-      <Setter Target="SecondaryButton.Foreground"
-              Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-    </VisualState.Setters>
-  </VisualState>-->
+  <Style Selector="SplitButton:checkedSecondaryPressed /template/ Border#Border">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checkedSecondaryPressed /template/ Rectangle#PrimaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checkedSecondaryPressed /template/ Rectangle#SecondaryBackgroundRectangle">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checkedSecondaryPressed /template/ Button#PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checkedSecondaryPressed /template/ Button#SecondaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
 
   <!--VisualStateGroup x:Name="SecondaryButtonPlacementStates">
     <VisualState x:Name="SecondaryButtonRight" />

From c0bb7efa12d9cfce1c1ae7532057d4e40062a11c Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Mon, 24 Jan 2022 23:59:57 -0500
Subject: [PATCH 10/48] Minor refactoring to Button noticed when adding
 SplitButton

---
 src/Avalonia.Controls/Button.cs | 61 +++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 22 deletions(-)

diff --git a/src/Avalonia.Controls/Button.cs b/src/Avalonia.Controls/Button.cs
index 8537c9acbc..770eb63266 100644
--- a/src/Avalonia.Controls/Button.cs
+++ b/src/Avalonia.Controls/Button.cs
@@ -76,6 +76,9 @@ namespace Avalonia.Controls
         public static readonly RoutedEvent<RoutedEventArgs> ClickEvent =
             RoutedEvent.Register<Button, RoutedEventArgs>(nameof(Click), RoutingStrategies.Bubble);
 
+        /// <summary>
+        /// Defines the <see cref="IsPressed"/> property.
+        /// </summary>
         public static readonly StyledProperty<bool> IsPressedProperty =
             AvaloniaProperty.Register<Button, bool>(nameof(IsPressed));
 
@@ -102,6 +105,9 @@ namespace Avalonia.Controls
             AccessKeyHandler.AccessKeyPressedEvent.AddClassHandler<Button>((lbl, args) => lbl.OnAccessKey(args));
         }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="Button"/> class.
+        /// </summary>
         public Button()
         {
             UpdatePseudoClasses(IsPressed);
@@ -112,8 +118,8 @@ namespace Avalonia.Controls
         /// </summary>
         public event EventHandler<RoutedEventArgs> Click
         {
-            add { AddHandler(ClickEvent, value); }
-            remove { RemoveHandler(ClickEvent, value); }
+            add => AddHandler(ClickEvent, value);
+            remove => RemoveHandler(ClickEvent, value);
         }
 
         /// <summary>
@@ -121,8 +127,8 @@ namespace Avalonia.Controls
         /// </summary>
         public ClickMode ClickMode
         {
-            get { return GetValue(ClickModeProperty); }
-            set { SetValue(ClickModeProperty, value); }
+            get => GetValue(ClickModeProperty);
+            set => SetValue(ClickModeProperty, value);
         }
 
         /// <summary>
@@ -130,8 +136,8 @@ namespace Avalonia.Controls
         /// </summary>
         public ICommand Command
         {
-            get { return _command; }
-            set { SetAndRaise(CommandProperty, ref _command, value); }
+            get => _command;
+            set => SetAndRaise(CommandProperty, ref _command, value);
         }
 
         /// <summary>
@@ -139,8 +145,8 @@ namespace Avalonia.Controls
         /// </summary>
         public KeyGesture HotKey
         {
-            get { return GetValue(HotKeyProperty); }
-            set { SetValue(HotKeyProperty, value); }
+            get => GetValue(HotKeyProperty);
+            set => SetValue(HotKeyProperty, value);
         }
 
         /// <summary>
@@ -148,8 +154,8 @@ namespace Avalonia.Controls
         /// </summary>
         public object CommandParameter
         {
-            get { return GetValue(CommandParameterProperty); }
-            set { SetValue(CommandParameterProperty, value); }
+            get => GetValue(CommandParameterProperty);
+            set => SetValue(CommandParameterProperty, value);
         }
 
         /// <summary>
@@ -158,8 +164,8 @@ namespace Avalonia.Controls
         /// </summary>
         public bool IsDefault
         {
-            get { return GetValue(IsDefaultProperty); }
-            set { SetValue(IsDefaultProperty, value); }
+            get => GetValue(IsDefaultProperty);
+            set => SetValue(IsDefaultProperty, value);
         }
 
         /// <summary>
@@ -168,18 +174,21 @@ namespace Avalonia.Controls
         /// </summary>
         public bool IsCancel
         {
-            get { return GetValue(IsCancelProperty); }
-            set { SetValue(IsCancelProperty, value); }
+            get => GetValue(IsCancelProperty);
+            set => SetValue(IsCancelProperty, value);
         }
 
+        /// <summary>
+        /// Gets or sets a value indicating whether the button is currently pressed.
+        /// </summary>
         public bool IsPressed
         {
-            get { return GetValue(IsPressedProperty); }
-            private set { SetValue(IsPressedProperty, value); }
+            get => GetValue(IsPressedProperty);
+            private set => SetValue(IsPressedProperty, value);
         }
 
         /// <summary>
-        /// Gets or sets the Flyout that should be shown with this button
+        /// Gets or sets the Flyout that should be shown with this button.
         /// </summary>
         public FlyoutBase Flyout
         {
@@ -187,7 +196,8 @@ namespace Avalonia.Controls
             set => SetValue(FlyoutProperty, value);
         }
 
-        protected override bool IsEnabledCore => base.IsEnabledCore && _commandCanExecute; 
+        /// <inheritdoc/>
+        protected override bool IsEnabledCore => base.IsEnabledCore && _commandCanExecute;
 
         /// <inheritdoc/>
         protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
@@ -224,6 +234,7 @@ namespace Avalonia.Controls
             }
         }
 
+        /// <inheritdoc/>
         protected override void OnAttachedToLogicalTree(LogicalTreeAttachmentEventArgs e)
         {
             if (_hotkey != null) // Control attached again, set Hotkey to create a hotkey manager for this control
@@ -240,6 +251,7 @@ namespace Avalonia.Controls
             }
         }
 
+        /// <inheritdoc/>
         protected override void OnDetachedFromLogicalTree(LogicalTreeAttachmentEventArgs e)
         {
             // This will cause the hotkey manager to dispose the observer and the reference to this control
@@ -358,12 +370,14 @@ namespace Avalonia.Controls
                 }
             }
         }
-        
+
+        /// <inheritdoc/>
         protected override void OnPointerCaptureLost(PointerCaptureLostEventArgs e)
         {
             IsPressed = false;
         }
 
+        /// <inheritdoc/>
         protected override void OnLostFocus(RoutedEventArgs e)
         {
             base.OnLostFocus(e);
@@ -371,6 +385,7 @@ namespace Avalonia.Controls
             IsPressed = false;
         }
 
+        /// <inheritdoc/>
         protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> change)
         {
             base.OnPropertyChanged(change);
@@ -391,6 +406,7 @@ namespace Avalonia.Controls
             }
         }
 
+        /// <inheritdoc/>
         protected override void UpdateDataValidation<T>(AvaloniaProperty<T> property, BindingValue<T> value)
         {
             base.UpdateDataValidation(property, value);
@@ -493,7 +509,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="sender">The event sender.</param>
         /// <param name="e">The event args.</param>
-        private void CanExecuteChanged(object sender, EventArgs e)
+        public void CanExecuteChanged(object sender, EventArgs e)
         {
             var canExecute = Command == null || Command.CanExecute(CommandParameter);
 
@@ -566,11 +582,12 @@ namespace Avalonia.Controls
             }
         }
 
+        /// <summary>
+        /// Updates the visual state of the control by applying latest PseudoClasses.
+        /// </summary>
         private void UpdatePseudoClasses(bool isPressed)
         {
             PseudoClasses.Set(":pressed", isPressed);
         }
-
-        void ICommandSource.CanExecuteChanged(object sender, EventArgs e) => this.CanExecuteChanged(sender, e);
     }
 }

From 7bdee77bf333e609f0c3bd0569e1806d5694f3b4 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 12:59:56 -0500
Subject: [PATCH 11/48] Make section heading comments smaller

---
 src/Avalonia.Controls/SplitButton/SplitButton.cs       | 10 ----------
 src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs |  8 --------
 2 files changed, 18 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index d30217ae4c..83fa157372 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -89,9 +89,7 @@ namespace Avalonia.Controls
         private IDisposable         _flyoutPropertyChangedDisposable;
 
         ////////////////////////////////////////////////////////////////////////
-        // 
         // Constructor / Destructors
-        //
         ////////////////////////////////////////////////////////////////////////
 
         /// <summary>
@@ -102,9 +100,7 @@ namespace Avalonia.Controls
         }
 
         ////////////////////////////////////////////////////////////////////////
-        // 
         // Properties
-        //
         ////////////////////////////////////////////////////////////////////////
 
         /// <summary>
@@ -148,9 +144,7 @@ namespace Avalonia.Controls
         protected override bool IsEnabledCore => base.IsEnabledCore && _commandCanExecute;
 
         ////////////////////////////////////////////////////////////////////////
-        // 
         // Methods
-        //
         ////////////////////////////////////////////////////////////////////////
 
         /// <inheritdoc/>
@@ -405,9 +399,7 @@ namespace Avalonia.Controls
         }
 
         ////////////////////////////////////////////////////////////////////////
-        // 
         // OnEvent Overridable Methods
-        //
         ////////////////////////////////////////////////////////////////////////
 
         /// <inheritdoc/>
@@ -622,9 +614,7 @@ namespace Avalonia.Controls
         }
 
         ////////////////////////////////////////////////////////////////////////
-        // 
         // Event Handling
-        //
         ////////////////////////////////////////////////////////////////////////
 
         /// <summary>
diff --git a/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs b/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
index c062f577de..f58ea569f2 100644
--- a/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
@@ -55,9 +55,7 @@ namespace Avalonia.Controls
                 nameof(IsChecked));
 
         ////////////////////////////////////////////////////////////////////////
-        // 
         // Constructor / Destructors
-        //
         ////////////////////////////////////////////////////////////////////////
 
         /// <summary>
@@ -68,9 +66,7 @@ namespace Avalonia.Controls
         }
 
         ////////////////////////////////////////////////////////////////////////
-        // 
         // Properties
-        //
         ////////////////////////////////////////////////////////////////////////
 
         /// <summary>
@@ -93,9 +89,7 @@ namespace Avalonia.Controls
         Type IStyleable.StyleKey => typeof(SplitButton);
 
         ////////////////////////////////////////////////////////////////////////
-        // 
         // Methods
-        //
         ////////////////////////////////////////////////////////////////////////
 
         /// <summary>
@@ -107,9 +101,7 @@ namespace Avalonia.Controls
         }
 
         ////////////////////////////////////////////////////////////////////////
-        // 
         // OnEvent Overridable Methods
-        //
         ////////////////////////////////////////////////////////////////////////
 
         /// <inheritdoc/>

From aa46b058819e342f356bf75d3f0008d6453a9077 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 13:11:49 -0500
Subject: [PATCH 12/48] Rework/rename PseudoClasses to match standards

---
 .../SplitButton/SplitButton.cs                |  58 +++++-----
 .../SplitButton/ToggleSplitButton.cs          |  18 ---
 .../Controls/SplitButton.xaml                 | 104 +++++++++---------
 3 files changed, 81 insertions(+), 99 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index 83fa157372..6bb2e2797e 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -15,21 +15,21 @@ namespace Avalonia.Controls
     /// </summary>
     [PseudoClasses(
         ":disabled",
-        ":secondaryButtonRight",
-        ":secondaryButtonSpan",
-        ":checkedFlyoutOpen",
-        ":flyoutOpen",
-        ":checkedTouchPressed",
+        ":secondary-button-right",
+        ":secondary-button-span",
+        ":checked-flyout-open",
+        ":flyout-open",
+        ":checked-touch-pressed",
         ":checked",
-        ":checkedPrimaryPressed",
-        ":checkedPrimaryPointerOver",
-        ":checkedSecondaryPressed",
-        ":checkedSecondaryPointerOver",
-        ":touchPressed",
-        ":primaryPressed",
-        ":primaryPointerOver",
-        ":secondaryPressed",
-        ":secondaryPointerOver")]
+        ":checked-primary-pressed",
+        ":checked-primary-pointerover",
+        ":checked-secondary-pressed",
+        ":checked-secondary-pointerover",
+        ":touch-pressed",
+        ":primary-pressed",
+        ":primary-pointerover",
+        ":secondary-pressed",
+        ":secondary-pointerover")]
     public class SplitButton : ContentControl, ICommandSource
     {
         /// <summary>
@@ -167,24 +167,24 @@ namespace Avalonia.Controls
             string pcNormal   = ":normal"; // Not supported in XAML style
             string pcDisabled = ":disabled";
 
-            string pcSecondaryButtonRight = ":secondaryButtonRight";
-            string pcSecondaryButtonSpan  = ":secondaryButtonSpan";
+            string pcSecondaryButtonRight = ":secondary-button-right";
+            string pcSecondaryButtonSpan  = ":secondary-button-span";
 
-            string pcCheckedFlyoutOpen = ":checkedFlyoutOpen";
-            string pcFlyoutOpen        = ":flyoutOpen";
+            string pcCheckedFlyoutOpen = ":checked-flyout-open";
+            string pcFlyoutOpen        = ":flyout-open";
 
-            string pcCheckedTouchPressed         = ":checkedTouchPressed";
+            string pcCheckedTouchPressed         = ":checked-touch-pressed";
             string pcChecked                     = ":checked";
-            string pcCheckedPrimaryPressed       = ":checkedPrimaryPressed";
-            string pcCheckedPrimaryPointerOver   = ":checkedPrimaryPointerOver";
-            string pcCheckedSecondaryPressed     = ":checkedSecondaryPressed";
-            string pcCheckedSecondaryPointerOver = ":checkedSecondaryPointerOver";
-
-            string pcTouchPressed         = ":touchPressed";
-            string pcPrimaryPressed       = ":primaryPressed";
-            string pcPrimaryPointerOver   = ":primaryPointerOver";
-            string pcSecondaryPressed     = ":secondaryPressed";
-            string pcSecondaryPointerOver = ":secondaryPointerOver";
+            string pcCheckedPrimaryPressed       = ":checked-primary-pressed";
+            string pcCheckedPrimaryPointerOver   = ":checked-primary-pointerover";
+            string pcCheckedSecondaryPressed     = ":checked-secondary-pressed";
+            string pcCheckedSecondaryPointerOver = ":checked-secondary-pointerover";
+
+            string pcTouchPressed         = ":touch-pressed";
+            string pcPrimaryPressed       = ":primary-pressed";
+            string pcPrimaryPointerOver   = ":primary-pointerover";
+            string pcSecondaryPressed     = ":secondary-pressed";
+            string pcSecondaryPointerOver = ":secondary-pointerover";
 
             // Place the secondary button
             // These are mutually exclusive PseudoClasses handled separately from SetExclusivePseudoClass().
diff --git a/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs b/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
index f58ea569f2..bd19fa213e 100644
--- a/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
@@ -1,5 +1,4 @@
 using System;
-using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Interactivity;
 using Avalonia.Styling;
@@ -11,23 +10,6 @@ namespace Avalonia.Controls
     /// The primary part behaves like a <see cref="ToggleButton"/> with two states and
     /// the secondary part opens a flyout.
     /// </summary>
-    [PseudoClasses(
-        ":disabled",
-        ":secondaryButtonRight",
-        ":secondaryButtonSpan",
-        ":checkedFlyoutOpen",
-        ":flyoutOpen",
-        ":checkedTouchPressed",
-        ":checked",
-        ":checkedPrimaryPressed",
-        ":checkedPrimaryPointerOver",
-        ":checkedSecondaryPressed",
-        ":checkedSecondaryPointerOver",
-        ":touchPressed",
-        ":primaryPressed",
-        ":primaryPointerOver",
-        ":secondaryPressed",
-        ":secondaryPointerOver")]
     public class ToggleSplitButton : SplitButton, IStyleable
     {
         /// <summary>
diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index 1b48f22a8c..a54926722f 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -153,83 +153,83 @@
   </Style>
 
   <!-- FlyoutOpen State -->
-  <Style Selector="SplitButton:flyoutOpen /template/ Rectangle#PrimaryBackgroundRectangle">
+  <Style Selector="SplitButton:flyout-open /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:flyoutOpen /template/ Rectangle#SecondaryBackgroundRectangle">
+  <Style Selector="SplitButton:flyout-open /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:flyoutOpen /template/ Border#Border">
+  <Style Selector="SplitButton:flyout-open /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
   </Style>
-  <Style Selector="SplitButton:flyoutOpen /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:flyout-open /template/ Button#PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:flyoutOpen /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:flyout-open /template/ Button#SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
 
   <!-- TouchPressed State -->
-  <Style Selector="SplitButton:touchPressed /template/ Rectangle#PrimaryBackgroundRectangle">
+  <Style Selector="SplitButton:touch-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:touchPressed /template/ Rectangle#SecondaryBackgroundRectangle">
+  <Style Selector="SplitButton:touch-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:touchPressed /template/ Border#Border">
+  <Style Selector="SplitButton:touch-pressed /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
   </Style>
-  <Style Selector="SplitButton:touchPressed /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:touch-pressed /template/ Button#PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:touchPressed /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:touch-pressed /template/ Button#SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
 
   <!-- PrimaryPointerOver State -->
-  <Style Selector="SplitButton:primaryPointerOver /template/ Rectangle#PrimaryBackgroundRectangle">
+  <Style Selector="SplitButton:primary-pointerover /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:primaryPointerOver /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:primary-pointerover /template/ Button#PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:primaryPointerOver /template/ Rectangle#SecondaryBackgroundRectangle">
+  <Style Selector="SplitButton:primary-pointerover /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackground}" />
   </Style>
 
   <!-- PrimaryPressed State -->
-  <Style Selector="SplitButton:primaryPressed /template/ Rectangle#PrimaryBackgroundRectangle">
+  <Style Selector="SplitButton:primary-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:primaryPressed /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:primary-pressed /template/ Button#PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:primaryPressed /template/ Rectangle#SecondaryBackgroundRectangle">
+  <Style Selector="SplitButton:primary-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackground}" />
   </Style>
 
   <!-- SecondaryPointerOver State -->
-  <Style Selector="SplitButton:secondaryPointerOver /template/ Rectangle#PrimaryBackgroundRectangle">
+  <Style Selector="SplitButton:secondary-pointerover /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackground}" />
   </Style>
-  <Style Selector="SplitButton:secondaryPointerOver /template/ Rectangle#SecondaryBackgroundRectangle">
+  <Style Selector="SplitButton:secondary-pointerover /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:secondaryPointerOver /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:secondary-pointerover /template/ Button#SecondaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
   </Style>
 
   <!-- SecondaryPressed State -->
-  <Style Selector="SplitButton:secondaryPressed /template/ Rectangle#PrimaryBackgroundRectangle">
+  <Style Selector="SplitButton:secondary-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackground}" />
   </Style>
-  <Style Selector="SplitButton:secondaryPressed /template/ Rectangle#SecondaryBackgroundRectangle">
+  <Style Selector="SplitButton:secondary-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:secondaryPressed /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:secondary-pressed /template/ Button#SecondaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
@@ -252,107 +252,107 @@
   </Style>
 
   <!-- CheckedFlyoutOpen State -->
-  <Style Selector="SplitButton:checkedFlyoutOpen /template/ Rectangle#PrimaryBackgroundRectangle">
+  <Style Selector="SplitButton:checked-flyout-open /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checkedFlyoutOpen /template/ Rectangle#SecondaryBackgroundRectangle">
+  <Style Selector="SplitButton:checked-flyout-open /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checkedFlyoutOpen /template/ Border#Border">
+  <Style Selector="SplitButton:checked-flyout-open /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checkedFlyoutOpen /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:checked-flyout-open /template/ Button#PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checkedFlyoutOpen /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:checked-flyout-open /template/ Button#SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
 
   <!-- CheckedTouchPressed State -->
-  <Style Selector="SplitButton:checkedTouchPressed /template/ Rectangle#PrimaryBackgroundRectangle">
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checkedTouchPressed /template/ Rectangle#SecondaryBackgroundRectangle">
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checkedTouchPressed /template/ Border#Border">
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checkedTouchPressed /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Button#PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checkedTouchPressed /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Button#SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
 
   <!-- CheckedPrimaryPointerOver State -->
-  <Style Selector="SplitButton:checkedPrimaryPointerOver /template/ Border#Border">
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
-  <Style Selector="SplitButton:checkedPrimaryPointerOver /template/ Rectangle#PrimaryBackgroundRectangle">
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:checkedPrimaryPointerOver /template/ Rectangle#SecondaryBackgroundRectangle">
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checkedPrimaryPointerOver /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:checkedPrimaryPointerOver /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
 
   <!-- CheckedPrimaryPressed State -->
-  <Style Selector="SplitButton:checkedPrimaryPressed /template/ Border#Border">
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
-  <Style Selector="SplitButton:checkedPrimaryPressed /template/ Rectangle#PrimaryBackgroundRectangle">
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checkedPrimaryPressed /template/ Rectangle#SecondaryBackgroundRectangle">
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checkedPrimaryPressed /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Button#PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checkedPrimaryPressed /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Button#SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
 
   <!-- CheckedSecondaryPointerOver State -->
-  <Style Selector="SplitButton:checkedSecondaryPointerOver /template/ Border#Border">
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
-  <Style Selector="SplitButton:checkedSecondaryPointerOver /template/ Rectangle#PrimaryBackgroundRectangle">
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checkedSecondaryPointerOver /template/ Rectangle#SecondaryBackgroundRectangle">
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:checkedSecondaryPointerOver /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Button#PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checkedSecondaryPointerOver /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Button#SecondaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
   </Style>
 
   <!-- CheckedSecondaryPressed State -->
-  <Style Selector="SplitButton:checkedSecondaryPressed /template/ Border#Border">
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
-  <Style Selector="SplitButton:checkedSecondaryPressed /template/ Rectangle#PrimaryBackgroundRectangle">
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checkedSecondaryPressed /template/ Rectangle#SecondaryBackgroundRectangle">
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checkedSecondaryPressed /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Button#PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checkedSecondaryPressed /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Button#SecondaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>

From d0dfac8a8b4d6d46aa073a47b71f64bd887c51fd Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 13:18:05 -0500
Subject: [PATCH 13/48] Remove ':normal' PseudoClass

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

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index 6bb2e2797e..bee9a5335f 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -164,7 +164,6 @@ namespace Avalonia.Controls
         /// </summary>
         protected void UpdatePseudoClasses()
         {
-            string pcNormal   = ":normal"; // Not supported in XAML style
             string pcDisabled = ":disabled";
 
             string pcSecondaryButtonRight = ":secondary-button-right";
@@ -263,7 +262,9 @@ namespace Avalonia.Controls
                         }
                         else
                         {
-                            SetExclusivePseudoClass(pcNormal);
+                            // Calling without a parameter is treated as ':normal' and will clear all other
+                            // PseudoClasses returning to the default state
+                            SetExclusivePseudoClass();
                         }
                     }
                     else if (_primaryButton.IsPressed)
@@ -284,7 +285,9 @@ namespace Avalonia.Controls
                     }
                     else
                     {
-                        SetExclusivePseudoClass(pcNormal);
+                        // Calling without a parameter is treated as ':normal' and will clear all other
+                        // PseudoClasses returning to the default state
+                        SetExclusivePseudoClass();
                     }
                 }
             }
@@ -293,7 +296,6 @@ namespace Avalonia.Controls
             // This more closely matches the VisualStateManager of WinUI where the default style originated
             void SetExclusivePseudoClass(string pseudoClass = "")
             {
-                PseudoClasses.Set(pcNormal,   pseudoClass == pcNormal);
                 PseudoClasses.Set(pcDisabled, pseudoClass == pcDisabled);
 
                 PseudoClasses.Set(pcCheckedFlyoutOpen, pseudoClass == pcCheckedFlyoutOpen);

From dcd85a8126fb9555182320349192c037a3af73ae Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 13:22:40 -0500
Subject: [PATCH 14/48] Make PseudoClass names class constants

---
 .../SplitButton/SplitButton.cs                | 74 +++++++++----------
 1 file changed, 37 insertions(+), 37 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index bee9a5335f..e2dda56758 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -14,24 +14,45 @@ namespace Avalonia.Controls
     /// The primary part behaves like a <see cref="Button"/> and the secondary part opens a flyout.
     /// </summary>
     [PseudoClasses(
-        ":disabled",
-        ":secondary-button-right",
-        ":secondary-button-span",
-        ":checked-flyout-open",
-        ":flyout-open",
-        ":checked-touch-pressed",
-        ":checked",
-        ":checked-primary-pressed",
-        ":checked-primary-pointerover",
-        ":checked-secondary-pressed",
-        ":checked-secondary-pointerover",
-        ":touch-pressed",
-        ":primary-pressed",
-        ":primary-pointerover",
-        ":secondary-pressed",
-        ":secondary-pointerover")]
+        pcDisabled,
+        pcSecondaryButtonRight,
+        pcSecondaryButtonSpan,
+        pcCheckedFlyoutOpen,
+        pcFlyoutOpen,
+        pcCheckedTouchPressed,
+        pcChecked,
+        pcCheckedPrimaryPressed,
+        pcCheckedPrimaryPointerOver,
+        pcCheckedSecondaryPressed,
+        pcCheckedSecondaryPointerOver,
+        pcTouchPressed,
+        pcPrimaryPressed,
+        pcPrimaryPointerOver,
+        pcSecondaryPressed,
+        pcSecondaryPointerOver)]
     public class SplitButton : ContentControl, ICommandSource
     {
+        private const string pcDisabled = ":disabled";
+
+        private const string pcSecondaryButtonRight = ":secondary-button-right";
+        private const string pcSecondaryButtonSpan  = ":secondary-button-span";
+
+        private const string pcCheckedFlyoutOpen = ":checked-flyout-open";
+        private const string pcFlyoutOpen        = ":flyout-open";
+
+        private const string pcCheckedTouchPressed         = ":checked-touch-pressed";
+        private const string pcChecked                     = ":checked";
+        private const string pcCheckedPrimaryPressed       = ":checked-primary-pressed";
+        private const string pcCheckedPrimaryPointerOver   = ":checked-primary-pointerover";
+        private const string pcCheckedSecondaryPressed     = ":checked-secondary-pressed";
+        private const string pcCheckedSecondaryPointerOver = ":checked-secondary-pointerover";
+
+        private const string pcTouchPressed         = ":touch-pressed";
+        private const string pcPrimaryPressed       = ":primary-pressed";
+        private const string pcPrimaryPointerOver   = ":primary-pointerover";
+        private const string pcSecondaryPressed     = ":secondary-pressed";
+        private const string pcSecondaryPointerOver = ":secondary-pointerover";
+
         /// <summary>
         /// Raised when the user presses the primary part of the <see cref="SplitButton"/>.
         /// </summary>
@@ -164,27 +185,6 @@ namespace Avalonia.Controls
         /// </summary>
         protected void UpdatePseudoClasses()
         {
-            string pcDisabled = ":disabled";
-
-            string pcSecondaryButtonRight = ":secondary-button-right";
-            string pcSecondaryButtonSpan  = ":secondary-button-span";
-
-            string pcCheckedFlyoutOpen = ":checked-flyout-open";
-            string pcFlyoutOpen        = ":flyout-open";
-
-            string pcCheckedTouchPressed         = ":checked-touch-pressed";
-            string pcChecked                     = ":checked";
-            string pcCheckedPrimaryPressed       = ":checked-primary-pressed";
-            string pcCheckedPrimaryPointerOver   = ":checked-primary-pointerover";
-            string pcCheckedSecondaryPressed     = ":checked-secondary-pressed";
-            string pcCheckedSecondaryPointerOver = ":checked-secondary-pointerover";
-
-            string pcTouchPressed         = ":touch-pressed";
-            string pcPrimaryPressed       = ":primary-pressed";
-            string pcPrimaryPointerOver   = ":primary-pointerover";
-            string pcSecondaryPressed     = ":secondary-pressed";
-            string pcSecondaryPointerOver = ":secondary-pointerover";
-
             // Place the secondary button
             // These are mutually exclusive PseudoClasses handled separately from SetExclusivePseudoClass().
             // They must be applied in addition to the others.

From 874a7f9a49d741f6887aa750b3360f0893465243 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 13:27:28 -0500
Subject: [PATCH 15/48] Fix incorrect names in SplitButton Styles

---
 .../Controls/SplitButton.xaml                 | 48 +++++++++----------
 1 file changed, 24 insertions(+), 24 deletions(-)

diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index a54926722f..8019ada8f3 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -162,10 +162,10 @@
   <Style Selector="SplitButton:flyout-open /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
   </Style>
-  <Style Selector="SplitButton:flyout-open /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:flyout-open /template/ Button#PART_PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:flyout-open /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:flyout-open /template/ Button#PART_SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
 
@@ -179,10 +179,10 @@
   <Style Selector="SplitButton:touch-pressed /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
   </Style>
-  <Style Selector="SplitButton:touch-pressed /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:touch-pressed /template/ Button#PART_PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:touch-pressed /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:touch-pressed /template/ Button#PART_SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
 
@@ -190,7 +190,7 @@
   <Style Selector="SplitButton:primary-pointerover /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:primary-pointerover /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:primary-pointerover /template/ Button#PART_PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
   </Style>
@@ -202,7 +202,7 @@
   <Style Selector="SplitButton:primary-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:primary-pressed /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:primary-pressed /template/ Button#PART_PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
@@ -217,7 +217,7 @@
   <Style Selector="SplitButton:secondary-pointerover /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:secondary-pointerover /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:secondary-pointerover /template/ Button#PART_SecondaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
   </Style>
@@ -229,7 +229,7 @@
   <Style Selector="SplitButton:secondary-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:secondary-pressed /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:secondary-pressed /template/ Button#PART_SecondaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
@@ -244,10 +244,10 @@
   <Style Selector="SplitButton:checked /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
 
@@ -261,10 +261,10 @@
   <Style Selector="SplitButton:checked-flyout-open /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:checked-flyout-open /template/ Button#PART_PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:checked-flyout-open /template/ Button#PART_SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
 
@@ -278,10 +278,10 @@
   <Style Selector="SplitButton:checked-touch-pressed /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Button#PART_PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Button#PART_SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
 
@@ -295,11 +295,11 @@
   <Style Selector="SplitButton:checked-primary-pointerover /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#PART_PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#PART_SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
 
@@ -313,11 +313,11 @@
   <Style Selector="SplitButton:checked-primary-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Button#PART_PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Button#PART_SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
 
@@ -331,10 +331,10 @@
   <Style Selector="SplitButton:checked-secondary-pointerover /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Button#PART_PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Button#PART_SecondaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
   </Style>
@@ -349,10 +349,10 @@
   <Style Selector="SplitButton:checked-secondary-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Button#PrimaryButton">
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Button#PART_PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Button#SecondaryButton">
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Button#PART_SecondaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
@@ -362,9 +362,9 @@
 
     <VisualState x:Name="SecondaryButtonSpan">
       <VisualState.Setters>
-        <Setter Target="SecondaryButton.(Grid.Column)"
+        <Setter Target="PART_SecondaryButton.(Grid.Column)"
                 Value="0" />
-        <Setter Target="SecondaryButton.(Grid.ColumnSpan)"
+        <Setter Target="PART_SecondaryButton.(Grid.ColumnSpan)"
                 Value="3" />
       </VisualState.Setters>
     </VisualState>

From 51e9ce9ef67dba49424bd82cf1b9a7e0d414cd40 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 13:27:45 -0500
Subject: [PATCH 16/48] Improve comments

---
 .../Accents/FluentControlResourcesDark.xaml                     | 2 +-
 .../Accents/FluentControlResourcesLight.xaml                    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesDark.xaml b/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesDark.xaml
index 085b03c96f..5b86de02d5 100644
--- a/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesDark.xaml
+++ b/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesDark.xaml
@@ -556,7 +556,7 @@
     <Thickness x:Key="TreeViewItemBorderThemeThickness">1</Thickness>
     <x:Double x:Key="TreeViewItemMinHeight">32</x:Double>
 
-    <!-- Resources for SplitButton.xaml -->
+    <!-- Resources for SplitButton.xaml (shared with ToggleSplitButton) -->
     <StaticResource x:Key="SplitButtonBackground" ResourceKey="SystemControlBackgroundBaseLowBrush" />
     <SolidColorBrush x:Key="SplitButtonBackgroundPointerOver" Color="{StaticResource SystemBaseHighColor}" Opacity="0.1" />
     <StaticResource x:Key="SplitButtonBackgroundPressed" ResourceKey="SystemControlBackgroundBaseMediumLowBrush" />
diff --git a/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesLight.xaml b/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesLight.xaml
index 702d2c60bc..eb68270354 100644
--- a/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesLight.xaml
+++ b/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesLight.xaml
@@ -550,7 +550,7 @@
     <Thickness x:Key="TreeViewItemBorderThemeThickness">1</Thickness>
     <x:Double x:Key="TreeViewItemMinHeight">32</x:Double>
 
-    <!-- Resources for SplitButton.xaml -->
+    <!-- Resources for SplitButton.xaml (shared with ToggleSplitButton) -->
     <StaticResource x:Key="SplitButtonBackground" ResourceKey="SystemControlBackgroundBaseLowBrush" />
     <SolidColorBrush x:Key="SplitButtonBackgroundPointerOver" Color="{StaticResource SystemBaseHighColor}" Opacity="0.1" />
     <StaticResource x:Key="SplitButtonBackgroundPressed" ResourceKey="SystemControlBackgroundBaseMediumLowBrush" />

From aa20c89e685b83e33e418ce85403ad3b1e6a6438 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 13:41:38 -0500
Subject: [PATCH 17/48] Set the DropDownGlyphPath Fill color directly in
 checked states

This is required for Avalonia after the switch to Path instead of TextBlock as in WinUI. WinUI glyph TextBlock just inherits the foreground color of the secondary button so doesn't need this.
---
 .../Controls/SplitButton.xaml                 | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index 8019ada8f3..78ba4532da 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -250,6 +250,9 @@
   <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
+  <Style Selector="SplitButton:checked /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
 
   <!-- CheckedFlyoutOpen State -->
   <Style Selector="SplitButton:checked-flyout-open /template/ Rectangle#PrimaryBackgroundRectangle">
@@ -267,6 +270,9 @@
   <Style Selector="SplitButton:checked-flyout-open /template/ Button#PART_SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
+  <Style Selector="SplitButton:checked-flyout-open /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
 
   <!-- CheckedTouchPressed State -->
   <Style Selector="SplitButton:checked-touch-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
@@ -284,6 +290,9 @@
   <Style Selector="SplitButton:checked-touch-pressed /template/ Button#PART_SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
 
   <!-- CheckedPrimaryPointerOver State -->
   <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#Border">
@@ -302,6 +311,9 @@
   <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#PART_SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
 
   <!-- CheckedPrimaryPressed State -->
   <Style Selector="SplitButton:checked-primary-pressed /template/ Border#Border">
@@ -320,6 +332,9 @@
   <Style Selector="SplitButton:checked-primary-pressed /template/ Button#PART_SecondaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
 
   <!-- CheckedSecondaryPointerOver State -->
   <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#Border">
@@ -338,6 +353,9 @@
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
   </Style>
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
+  </Style>
 
   <!-- CheckedSecondaryPressed State -->
   <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#Border">
@@ -356,6 +374,9 @@
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
 
   <!--VisualStateGroup x:Name="SecondaryButtonPlacementStates">
     <VisualState x:Name="SecondaryButtonRight" />

From 3a3db396bea4020a9784dd60919dd183546855a9 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 13:45:52 -0500
Subject: [PATCH 18/48] Add Design.PreviewWith to SplitButton.xaml

---
 src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index 78ba4532da..809cede59a 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -1,7 +1,11 @@
 <Styles xmlns="https://github.com/avaloniaui"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         x:CompileBindings="True">
+
   <Design.PreviewWith>
+    <Border Padding="20">
+      <SplitButton />
+    </Border>
   </Design.PreviewWith>
 
   <Styles.Resources>

From 1b832871dc66d87a7218c70db8082c19d99663f5 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 14:06:58 -0500
Subject: [PATCH 19/48] Add disabled secondary-button-span style

---
 .../Controls/SplitButton.xaml                  | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index 809cede59a..681e5339ea 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -382,17 +382,11 @@
     <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
 
-  <!--VisualStateGroup x:Name="SecondaryButtonPlacementStates">
-    <VisualState x:Name="SecondaryButtonRight" />
-
-    <VisualState x:Name="SecondaryButtonSpan">
-      <VisualState.Setters>
-        <Setter Target="PART_SecondaryButton.(Grid.Column)"
-                Value="0" />
-        <Setter Target="PART_SecondaryButton.(Grid.ColumnSpan)"
-                Value="3" />
-      </VisualState.Setters>
-    </VisualState>
-  </VisualStateGroup-->
+  <!-- SecondaryButtonPlacement States -->
+  <!-- Note: ':secondary-button-right' is the default -->
+  <!--<Style Selector="SplitButton:secondary-button-span /template/ Button#PART_SecondaryButton">
+    <Setter Property="(Grid.Column)" Value="0" />
+    <Setter Property="(Grid.ColumnSpan)" Value="3" />
+  </Style>-->
 
 </Styles>

From c2cebb32fa5423ba174b9a87817f11a3c3fa40a3 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 14:38:38 -0500
Subject: [PATCH 20/48] Pulled out 'child' Primary/SecondaryButton style

---
 .../Controls/SplitButton.xaml                 | 71 ++++++++++---------
 1 file changed, 36 insertions(+), 35 deletions(-)

diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index 681e5339ea..bd3996e399 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -36,41 +36,9 @@
           <Border Background="Transparent"
                   CornerRadius="{TemplateBinding CornerRadius}"
                   ClipToBounds="True">
-            <Border.Styles>
-              <!-- Override the style of the inner buttons so that they don't affect background/foreground/border colors -->
-              <Style Selector="Button">
-                <Setter Property="Foreground" Value="{DynamicResource SplitButtonForeground}" />
-                <Setter Property="BorderBrush" Value="Transparent" />
-                <Setter Property="BorderThickness" Value="{DynamicResource SplitButtonBorderThemeThickness}" />
-                <Setter Property="HorizontalAlignment" Value="Left" />
-                <Setter Property="VerticalAlignment" Value="Center" />
-                <!--<Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}" />
-                <Setter Property="FontWeight" Value="Normal" />
-                <Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}" />
-                <Setter Property="UseSystemFocusVisuals" Value="{StaticResource UseSystemFocusVisuals}" />
-                <Setter Property="FocusVisualMargin" Value="-3" />-->
-                <Setter Property="Template">
-                  <ControlTemplate>
-                    <!-- Switched from Grid to Border to optimize and support Foreground/Background properties -->
-                    <Border x:Name="RootBorder"
-                            Background="Transparent">
-                      <ContentPresenter x:Name="ContentPresenter"
-                                        BorderBrush="{TemplateBinding BorderBrush}"
-                                        BorderThickness="{TemplateBinding BorderThickness}"
-                                        Content="{TemplateBinding Content}"
-                                        ContentTemplate="{TemplateBinding ContentTemplate}"
-                                        Padding="{TemplateBinding Padding}"
-                                        HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
-                                        VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" />
-                    </Border>
-                  </ControlTemplate>
-                </Setter>
-              </Style>
-              <Style Selector="Button:disabled">
-                <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundDisabled}" />
-                <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundDisabled}" />
-              </Style>
-            </Border.Styles>
+            <!-- In WinUI, a separate child style for the inner buttons is provided here.
+                 For avalonia that style is simplified and pulled out separately below.
+                 A style is needed to override any button default background/foreground/border colors, etc. -->
             <Grid>
               
               <Grid.ColumnDefinitions>
@@ -148,6 +116,34 @@
     </Setter>
   </Style>
 
+  <!-- Normal State (not a PseudoClass) -->
+  <!-- The 'Button' style here was moved out of the main style above.
+       In WinUI there is a child, customized style shared for both primary and secondary buttons.
+       In Avalonia, we can use selectors to make a 'normal' style apply only to those buttons but
+       pull it out separately from the full style above. -->
+  <Style Selector="SplitButton /template/ Button">
+    <!-- Applies to both Primary/Secondary buttons -->
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForeground}" />
+    <Setter Property="BorderBrush" Value="Transparent" />
+    <Setter Property="BorderThickness" Value="{DynamicResource SplitButtonBorderThemeThickness}" />
+    <Setter Property="Template">
+      <ControlTemplate>
+        <!-- Switched from Grid to Border to optimize and support Foreground/Background properties -->
+        <!-- It is important for the background to be clear and no CornerRadius set. -->
+        <Border Background="Transparent">
+          <ContentPresenter x:Name="ContentPresenter"
+                            BorderBrush="{TemplateBinding BorderBrush}"
+                            BorderThickness="{TemplateBinding BorderThickness}"
+                            Content="{TemplateBinding Content}"
+                            ContentTemplate="{TemplateBinding ContentTemplate}"
+                            Padding="{TemplateBinding Padding}"
+                            HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                            VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" />
+        </Border>
+      </ControlTemplate>
+    </Setter>
+  </Style>
+
   <!-- Disabled State -->
   <Style Selector="SplitButton:disabled /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushDisabled}" />
@@ -155,6 +151,11 @@
   <Style Selector="SplitButton:disabled /template/ Path#DropDownGlyphPath">
     <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundDisabled}" />
   </Style>
+  <Style Selector="SplitButton:disabled /template/ Button">
+    <!-- Applies to both Primary/Secondary buttons -->
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundDisabled}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundDisabled}" />
+  </Style>
 
   <!-- FlyoutOpen State -->
   <Style Selector="SplitButton:flyout-open /template/ Rectangle#PrimaryBackgroundRectangle">

From 1a40c45ec9cdde067b0e3245d4889b9020f777ee Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 14:57:00 -0500
Subject: [PATCH 21/48] Fix handling of shared flyouts

---
 .../SplitButton/SplitButton.cs                | 25 ++++++++++++++++---
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index e2dda56758..efb7587960 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -685,8 +685,19 @@ namespace Avalonia.Controls
         /// </summary>
         private void Flyout_Opened(object sender, EventArgs e)
         {
-            _isFlyoutOpen = true;
-            UpdatePseudoClasses();
+            var flyout = sender as FlyoutBase;
+
+            // It is possible to share flyouts among multiple controls including SplitButton.
+            // This can cause a problem here since all controls that share a flyout receive
+            // the same Opened/Closed events at the same time.
+            // For SplitButton that means they all would be updating their pseudoclasses accordingly.
+            // In other words, all SplitButtons with a shared Flyout would have the backgrounds changed together.
+            // To fix this, only continue here if the Flyout target matches this SplitButton instance.
+            if (object.ReferenceEquals(flyout?.Target, this))
+            {
+                _isFlyoutOpen = true;
+                UpdatePseudoClasses();
+            }
         }
 
         /// <summary>
@@ -694,8 +705,14 @@ namespace Avalonia.Controls
         /// </summary>
         private void Flyout_Closed(object sender, EventArgs e)
         {
-            _isFlyoutOpen = false;
-            UpdatePseudoClasses();
+            var flyout = sender as FlyoutBase;
+
+            // See comments in Flyout_Opened
+            if (object.ReferenceEquals(flyout?.Target, this))
+            {
+                _isFlyoutOpen = false;
+                UpdatePseudoClasses();
+            }
         }
     }
 }

From a57bdbc25433775861b40e3a4c00136a7f9f50fd Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 19:25:48 -0500
Subject: [PATCH 22/48] Implement secondary button span but disable it with
 commented reasons

---
 .../SplitButton/SplitButton.cs                | 23 ++++++++++++++++---
 .../Controls/SplitButton.xaml                 | 23 ++++++++++++-------
 2 files changed, 35 insertions(+), 11 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index efb7587960..ceff577eda 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -186,8 +186,24 @@ namespace Avalonia.Controls
         protected void UpdatePseudoClasses()
         {
             // Place the secondary button
-            // These are mutually exclusive PseudoClasses handled separately from SetExclusivePseudoClass().
-            // They must be applied in addition to the others.
+            //
+            // In WinUI, the span of the secondary button is changed to full-width for touch-based
+            // devices in certain conditions. The full reasoning for this is unknown. Some theories
+            // include:
+            //
+            //   My guess is that the design team at MS decided that it's a better experience
+            //   for touch users to make them select from the drop down rather than the shortcut
+            //   top level button, so touch basically just turns this into a drop down button.
+            //   Whether that's ideal or not is going is a subjective opinion.
+            //
+            // For Avalonia, it may not always make sense to disable the primary button like that
+            // on touch-first platforms. Users and developers would normally expect a control to
+            // function the same on all platforms. Therefore, this functionality is disabled here
+            // but could be re-enabled in the future if more reasons become known.
+            //
+            // Finally, these are mutually exclusive PseudoClasses handled separately from
+            // SetExclusivePseudoClass(). They must be applied in addition to the others.
+            /*
             if (_lastPointerType == PointerType.Touch || _isKeyDown)
             {
                 PseudoClasses.Set(pcSecondaryButtonSpan, true);
@@ -198,9 +214,10 @@ namespace Avalonia.Controls
                 PseudoClasses.Set(pcSecondaryButtonSpan, false);
                 PseudoClasses.Set(pcSecondaryButtonRight, true);
             }
+            */
 
             // Change the visual state
-            if (!IsEnabled)
+            if (!IsEffectivelyEnabled)
             {
                 SetExclusivePseudoClass(pcDisabled);
             }
diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index bd3996e399..fd1ab4d9b4 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -10,7 +10,7 @@
 
   <Styles.Resources>
     <x:Double x:Key="SplitButtonPrimaryButtonSize">32</x:Double>
-    <x:Double x:Key="SplitButtonSecondaryButtonSize">32</x:Double>
+    <GridLength x:Key="SplitButtonSecondaryButtonSize">32</GridLength>
   </Styles.Resources>
 
   <Style Selector="SplitButton">
@@ -43,9 +43,9 @@
               
               <Grid.ColumnDefinitions>
                 <ColumnDefinition Width="*"
-                                  MinWidth="{DynamicResource SplitButtonPrimaryButtonSize}" />
+                                  MinWidth="{StaticResource SplitButtonPrimaryButtonSize}" />
                 <ColumnDefinition Width="1" />
-                <ColumnDefinition Width="{DynamicResource SplitButtonSecondaryButtonSize}" />
+                <ColumnDefinition Width="{StaticResource SplitButtonSecondaryButtonSize}" />
               </Grid.ColumnDefinitions>
 
               <!-- Changed from Grid to Rectangle since Avalonia does not support Background on Grid directly -->
@@ -89,11 +89,12 @@
                       Background="{TemplateBinding Background}"
                       BorderThickness="{TemplateBinding BorderThickness}"
                       BorderBrush="Transparent"
-                      HorizontalContentAlignment="Center"
+                      HorizontalContentAlignment="Right"
                       VerticalContentAlignment="Center"
                       HorizontalAlignment="Stretch"
                       VerticalAlignment="Stretch"
-                      KeyboardNavigation.IsTabStop="False">
+                      KeyboardNavigation.IsTabStop="False"
+                      Padding="0,0,10,0">
                 <Button.Content>
                   <!-- TextBlock converted to a Path and placed within Viewbox -->
                   <Viewbox UseLayoutRounding="False"
@@ -384,10 +385,16 @@
   </Style>
 
   <!-- SecondaryButtonPlacement States -->
-  <!-- Note: ':secondary-button-right' is the default -->
-  <!--<Style Selector="SplitButton:secondary-button-span /template/ Button#PART_SecondaryButton">
+  <!-- Note: Setting Grid attached properties doesn't work here for some unknown reason.
+       They simply are never changed. In addition, touch-device changes of secondary button
+       size are currently disabled in code-behind. -->
+  <Style Selector="SplitButton:secondary-button-right /template/ Button#PART_SecondaryButton">
+    <Setter Property="(Grid.Column)" Value="2" />
+    <Setter Property="(Grid.ColumnSpan)" Value="1" />
+  </Style>
+  <Style Selector="SplitButton:secondary-button-span /template/ Button#PART_SecondaryButton">
     <Setter Property="(Grid.Column)" Value="0" />
     <Setter Property="(Grid.ColumnSpan)" Value="3" />
-  </Style>-->
+  </Style>
 
 </Styles>

From 853d4140a301f09cfa4bc4727c086459de903169 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 20:02:40 -0500
Subject: [PATCH 23/48] Move more Button property changed handling into
 OnPropertyChanged override

---
 src/Avalonia.Controls/Button.cs               | 142 +++++++-----------
 .../SplitButton/SplitButton.cs                |   4 +-
 2 files changed, 57 insertions(+), 89 deletions(-)

diff --git a/src/Avalonia.Controls/Button.cs b/src/Avalonia.Controls/Button.cs
index 770eb63266..3735e6c010 100644
--- a/src/Avalonia.Controls/Button.cs
+++ b/src/Avalonia.Controls/Button.cs
@@ -59,13 +59,13 @@ namespace Avalonia.Controls
             AvaloniaProperty.Register<Button, object>(nameof(CommandParameter));
 
         /// <summary>
-        /// Defines the <see cref="IsDefaultProperty"/> property.
+        /// Defines the <see cref="IsDefault"/> property.
         /// </summary>
         public static readonly StyledProperty<bool> IsDefaultProperty =
             AvaloniaProperty.Register<Button, bool>(nameof(IsDefault));
 
         /// <summary>
-        /// Defines the <see cref="IsCancelProperty"/> property.
+        /// Defines the <see cref="IsCancel"/> property.
         /// </summary>
         public static readonly StyledProperty<bool> IsCancelProperty =
             AvaloniaProperty.Register<Button, bool>(nameof(IsCancel));
@@ -98,10 +98,6 @@ namespace Avalonia.Controls
         static Button()
         {
             FocusableProperty.OverrideDefaultValue(typeof(Button), true);
-            CommandProperty.Changed.Subscribe(CommandChanged);
-            CommandParameterProperty.Changed.Subscribe(CommandParameterChanged);
-            IsDefaultProperty.Changed.Subscribe(IsDefaultChanged);
-            IsCancelProperty.Changed.Subscribe(IsCancelChanged);
             AccessKeyHandler.AccessKeyPressedEvent.AddClassHandler<Button>((lbl, args) => lbl.OnAccessKey(args));
         }
 
@@ -390,116 +386,88 @@ namespace Avalonia.Controls
         {
             base.OnPropertyChanged(change);
 
-            if (change.Property == IsPressedProperty)
+            if (change.Property == CommandProperty)
             {
-                UpdatePseudoClasses(change.NewValue.GetValueOrDefault<bool>());
-            }
-            else if (change.Property == FlyoutProperty)
-            {
-                // If flyout is changed while one is already open, make sure we 
-                // close the old one first
-                if (change.OldValue.GetValueOrDefault() is FlyoutBase oldFlyout &&
-                    oldFlyout.IsOpen)
+                if (((ILogical)this).IsAttachedToLogicalTree)
                 {
-                    oldFlyout.Hide();
+                    if (change.OldValue.GetValueOrDefault() is ICommand oldCommand)
+                    {
+                        oldCommand.CanExecuteChanged -= CanExecuteChanged;
+                    }
+
+                    if (change.NewValue.GetValueOrDefault() is ICommand newCommand)
+                    {
+                        newCommand.CanExecuteChanged += CanExecuteChanged;
+                    }
                 }
-            }
-        }
 
-        /// <inheritdoc/>
-        protected override void UpdateDataValidation<T>(AvaloniaProperty<T> property, BindingValue<T> value)
-        {
-            base.UpdateDataValidation(property, value);
-            if (property == CommandProperty)
+                CanExecuteChanged(this, EventArgs.Empty);
+            }
+            else if (change.Property == CommandParameterProperty)
             {
-                if (value.Type == BindingValueType.BindingError)
+                CanExecuteChanged(this, EventArgs.Empty);
+            }
+            else if (change.Property == IsCancelProperty)
+            {
+                var isCancel = change.NewValue.GetValueOrDefault<bool>();
+
+                if (VisualRoot is IInputElement inputRoot)
                 {
-                    if (_commandCanExecute)
+                    if (isCancel)
                     {
-                        _commandCanExecute = false;
-                        UpdateIsEffectivelyEnabled();
+                        ListenForCancel(inputRoot);
+                    }
+                    else
+                    {
+                        StopListeningForCancel(inputRoot);
                     }
                 }
             }
-        }
-
-        /// <summary>
-        /// Called when the <see cref="Command"/> property changes.
-        /// </summary>
-        /// <param name="e">The event args.</param>
-        private static void CommandChanged(AvaloniaPropertyChangedEventArgs e)
-        {
-            if (e.Sender is Button button)
+            else if (change.Property == IsDefaultProperty)
             {
-                if (((ILogical)button).IsAttachedToLogicalTree)
+                var isDefault = change.NewValue.GetValueOrDefault<bool>();
+
+                if (VisualRoot is IInputElement inputRoot)
                 {
-                    if (e.OldValue is ICommand oldCommand)
+                    if (isDefault)
                     {
-                        oldCommand.CanExecuteChanged -= button.CanExecuteChanged;
+                        ListenForDefault(inputRoot);
                     }
-
-                    if (e.NewValue is ICommand newCommand)
+                    else
                     {
-                        newCommand.CanExecuteChanged += button.CanExecuteChanged;
+                        StopListeningForDefault(inputRoot);
                     }
                 }
-
-                button.CanExecuteChanged(button, EventArgs.Empty);
             }
-        }
-
-        /// <summary>
-        /// Called when the <see cref="CommandParameter"/> property changes.
-        /// </summary>
-        /// <param name="e">The event args.</param>
-        private static void CommandParameterChanged(AvaloniaPropertyChangedEventArgs e)
-        {
-            if (e.Sender is Button button)
+            else if (change.Property == IsPressedProperty)
             {
-                button.CanExecuteChanged(button, EventArgs.Empty);
+                UpdatePseudoClasses(change.NewValue.GetValueOrDefault<bool>());
             }
-        }
-
-        /// <summary>
-        /// Called when the <see cref="IsDefault"/> property changes.
-        /// </summary>
-        /// <param name="e">The event args.</param>
-        private static void IsDefaultChanged(AvaloniaPropertyChangedEventArgs e)
-        {
-            var button = e.Sender as Button;
-            var isDefault = (bool)e.NewValue;
-
-            if (button?.VisualRoot is IInputElement inputRoot)
+            else if (change.Property == FlyoutProperty)
             {
-                if (isDefault)
-                {
-                    button.ListenForDefault(inputRoot);
-                }
-                else
+                // If flyout is changed while one is already open, make sure we 
+                // close the old one first
+                if (change.OldValue.GetValueOrDefault() is FlyoutBase oldFlyout &&
+                    oldFlyout.IsOpen)
                 {
-                    button.StopListeningForDefault(inputRoot);
+                    oldFlyout.Hide();
                 }
             }
         }
 
-        /// <summary>
-        /// Called when the <see cref="IsCancel"/> property changes.
-        /// </summary>
-        /// <param name="e">The event args.</param>
-        private static void IsCancelChanged(AvaloniaPropertyChangedEventArgs e)
+        /// <inheritdoc/>
+        protected override void UpdateDataValidation<T>(AvaloniaProperty<T> property, BindingValue<T> value)
         {
-            var button = e.Sender as Button;
-            var isCancel = (bool)e.NewValue;
-
-            if (button?.VisualRoot is IInputElement inputRoot)
+            base.UpdateDataValidation(property, value);
+            if (property == CommandProperty)
             {
-                if (isCancel)
-                {
-                    button.ListenForCancel(inputRoot);
-                }
-                else
+                if (value.Type == BindingValueType.BindingError)
                 {
-                    button.StopListeningForCancel(inputRoot);
+                    if (_commandCanExecute)
+                    {
+                        _commandCanExecute = false;
+                        UpdateIsEffectivelyEnabled();
+                    }
                 }
             }
         }
diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index ceff577eda..5c75a8d09d 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -515,12 +515,12 @@ namespace Avalonia.Controls
                 if (_isAttachedToLogicalTree)
                 {
                     // Must unregister events here while a reference to the old command still exists
-                    if (e.OldValue is ICommand oldCommand)
+                    if (e.OldValue.GetValueOrDefault() is ICommand oldCommand)
                     {
                         oldCommand.CanExecuteChanged -= CanExecuteChanged;
                     }
 
-                    if (e.NewValue is ICommand newCommand)
+                    if (e.NewValue.GetValueOrDefault() is ICommand newCommand)
                     {
                         newCommand.CanExecuteChanged += CanExecuteChanged;
                     }

From 9b1dd0dca0bfbca7c13261b284b0015e891b51ee Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 22:25:09 -0500
Subject: [PATCH 24/48] Copy over some Flyout logic from Button

---
 .../SplitButton/SplitButton.cs                | 23 +++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index 5c75a8d09d..c3de65b14d 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -534,13 +534,25 @@ namespace Avalonia.Controls
             }
             else if (e.Property == FlyoutProperty)
             {
+                var oldFlyout = e.OldValue.GetValueOrDefault() as FlyoutBase;
+                var newFlyout = e.NewValue.GetValueOrDefault() as FlyoutBase;
+
+                // If flyout is changed while one is already open, make sure we 
+                // close the old one first
+                // This is the same behavior as Button
+                if (oldFlyout != null &&
+                    oldFlyout.IsOpen)
+                {
+                    oldFlyout.Hide();
+                }
+
                 // Must unregister events here while a reference to the old flyout still exists
-                if (e.OldValue.GetValueOrDefault() is FlyoutBase oldFlyout)
+                if (oldFlyout != null)
                 {
                     UnregisterFlyoutEvents(oldFlyout);
                 }
 
-                if (e.NewValue.GetValueOrDefault() is FlyoutBase newFlyout)
+                if (newFlyout != null)
                 {
                     RegisterFlyoutEvents(newFlyout);
                 }
@@ -595,6 +607,13 @@ namespace Avalonia.Controls
                 OpenFlyout();
                 e.Handled = true;
             }
+            else if (e.Key == Key.Escape && _isFlyoutOpen)
+            {
+                // If Flyout doesn't have focusable content, close the flyout here
+                // This is the same behavior as Button
+                CloseFlyout();
+                e.Handled = true;
+            }
 
             base.OnKeyUp(e);
         }

From 3c8533467d5536553243e8f5dc26136662fcc72e Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 23:14:37 -0500
Subject: [PATCH 25/48] Use existing button property definitions

---
 src/Avalonia.Controls/SplitButton/SplitButton.cs | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index c3de65b14d..5b85a19b8a 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -74,25 +74,21 @@ namespace Avalonia.Controls
         /// Defines the <see cref="Command"/> property.
         /// </summary>
         public static readonly DirectProperty<SplitButton, ICommand> CommandProperty =
-            AvaloniaProperty.RegisterDirect<SplitButton, ICommand>(
-                nameof(Command),
+            Button.CommandProperty.AddOwner<SplitButton>(
                 splitButton => splitButton.Command,
-                (splitButton, command) => splitButton.Command = command,
-                enableDataValidation: true);
+                (splitButton, command) => splitButton.Command = command);
 
         /// <summary>
         /// Defines the <see cref="CommandParameter"/> property.
         /// </summary>
         public static readonly StyledProperty<object> CommandParameterProperty =
-            AvaloniaProperty.Register<SplitButton, object>(
-                nameof(CommandParameter));
+            Button.CommandParameterProperty.AddOwner<SplitButton>();
 
         /// <summary>
         /// Defines the <see cref="Flyout"/> property
         /// </summary>
         public static readonly StyledProperty<FlyoutBase> FlyoutProperty =
-            AvaloniaProperty.Register<SplitButton, FlyoutBase>(
-                nameof(Flyout));
+            Button.FlyoutProperty.AddOwner<SplitButton>();
 
         private ICommand _Command;
 

From 7773a1d5b867a7d5220d64285da6a63223a5840d Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 23:32:22 -0500
Subject: [PATCH 26/48] Remove ClipToBounds and set CornerRadius on each child

This will remove the clipping work-around and also better support future styles that may need border in children (Fluent v2)
---
 .../Controls/SplitButton.xaml                 | 124 +++++++++---------
 1 file changed, 63 insertions(+), 61 deletions(-)

diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index fd1ab4d9b4..0e5ccf4ec3 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -32,10 +32,8 @@
       <Setter.Value>
         <ControlTemplate>
           <!-- A Border was added here since Avalonia does not support Background/Border/CornerRadius on Grid directly -->
-          <!-- ClipToBounds added as a temporary work-around for: https://github.com/AvaloniaUI/Avalonia/issues/2105 -->
           <Border Background="Transparent"
-                  CornerRadius="{TemplateBinding CornerRadius}"
-                  ClipToBounds="True">
+                  CornerRadius="{TemplateBinding CornerRadius}">
             <!-- In WinUI, a separate child style for the inner buttons is provided here.
                  For avalonia that style is simplified and pulled out separately below.
                  A style is needed to override any button default background/foreground/border colors, etc. -->
@@ -48,13 +46,15 @@
                 <ColumnDefinition Width="{StaticResource SplitButtonSecondaryButtonSize}" />
               </Grid.ColumnDefinitions>
 
-              <!-- Changed from Grid to Rectangle since Avalonia does not support Background on Grid directly -->
-              <Rectangle x:Name="PrimaryBackgroundRectangle"
-                         Fill="{TemplateBinding Background}" />
+              <!-- Changed from Grid to Border since Avalonia does not support Background/CornerRadius on Grid directly -->
+              <Border x:Name="PrimaryBackgroundBorder"
+                      Background="{TemplateBinding Background}"
+                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource LeftCornerRadiusFilterConverter}}" />
 
-              <Rectangle x:Name="SecondaryBackgroundRectangle"
-                         Fill="{TemplateBinding Background}"
-                         Grid.Column="2" />
+              <Border x:Name="SecondaryBackgroundBorder"
+                      Background="{TemplateBinding Background}"
+                      Grid.Column="2"
+                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource RightCornerRadiusFilterConverter}}" />
 
               <!-- Changed from Grid to Border to support Background/Border/CornerRadius properties -->
               <Border x:Name="Border"
@@ -73,6 +73,7 @@
                       ContentTemplate="{TemplateBinding ContentTemplate}"
                       Command="{TemplateBinding Command}"
                       CommandParameter="{TemplateBinding CommandParameter}"
+                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource LeftCornerRadiusFilterConverter}}"
                       FontFamily="{TemplateBinding FontFamily}"
                       FontSize="{TemplateBinding FontSize}"
                       FontWeight="{TemplateBinding FontWeight}"
@@ -85,6 +86,7 @@
 
               <Button x:Name="PART_SecondaryButton"
                       Grid.Column="2"
+                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource RightCornerRadiusFilterConverter}}"
                       Foreground="{TemplateBinding Foreground}"
                       Background="{TemplateBinding Background}"
                       BorderThickness="{TemplateBinding BorderThickness}"
@@ -159,11 +161,11 @@
   </Style>
 
   <!-- FlyoutOpen State -->
-  <Style Selector="SplitButton:flyout-open /template/ Rectangle#PrimaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  <Style Selector="SplitButton:flyout-open /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:flyout-open /template/ Rectangle#SecondaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  <Style Selector="SplitButton:flyout-open /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
   <Style Selector="SplitButton:flyout-open /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
@@ -176,11 +178,11 @@
   </Style>
 
   <!-- TouchPressed State -->
-  <Style Selector="SplitButton:touch-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  <Style Selector="SplitButton:touch-pressed /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:touch-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  <Style Selector="SplitButton:touch-pressed /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
   <Style Selector="SplitButton:touch-pressed /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
@@ -193,35 +195,35 @@
   </Style>
 
   <!-- PrimaryPointerOver State -->
-  <Style Selector="SplitButton:primary-pointerover /template/ Rectangle#PrimaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
+  <Style Selector="SplitButton:primary-pointerover /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
   </Style>
   <Style Selector="SplitButton:primary-pointerover /template/ Button#PART_PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:primary-pointerover /template/ Rectangle#SecondaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackground}" />
+  <Style Selector="SplitButton:primary-pointerover /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
   </Style>
 
   <!-- PrimaryPressed State -->
-  <Style Selector="SplitButton:primary-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  <Style Selector="SplitButton:primary-pressed /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
   <Style Selector="SplitButton:primary-pressed /template/ Button#PART_PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:primary-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackground}" />
+  <Style Selector="SplitButton:primary-pressed /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
   </Style>
 
   <!-- SecondaryPointerOver State -->
-  <Style Selector="SplitButton:secondary-pointerover /template/ Rectangle#PrimaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackground}" />
+  <Style Selector="SplitButton:secondary-pointerover /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
   </Style>
-  <Style Selector="SplitButton:secondary-pointerover /template/ Rectangle#SecondaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
+  <Style Selector="SplitButton:secondary-pointerover /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
   </Style>
   <Style Selector="SplitButton:secondary-pointerover /template/ Button#PART_SecondaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
@@ -229,11 +231,11 @@
   </Style>
 
   <!-- SecondaryPressed State -->
-  <Style Selector="SplitButton:secondary-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackground}" />
+  <Style Selector="SplitButton:secondary-pressed /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
   </Style>
-  <Style Selector="SplitButton:secondary-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  <Style Selector="SplitButton:secondary-pressed /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
   <Style Selector="SplitButton:secondary-pressed /template/ Button#PART_SecondaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
@@ -241,11 +243,11 @@
   </Style>
 
   <!-- Checked State -->
-  <Style Selector="SplitButton:checked /template/ Rectangle#PrimaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  <Style Selector="SplitButton:checked /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked /template/ Rectangle#SecondaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  <Style Selector="SplitButton:checked /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
   </Style>
   <Style Selector="SplitButton:checked /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
@@ -261,11 +263,11 @@
   </Style>
 
   <!-- CheckedFlyoutOpen State -->
-  <Style Selector="SplitButton:checked-flyout-open /template/ Rectangle#PrimaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  <Style Selector="SplitButton:checked-flyout-open /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Rectangle#SecondaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  <Style Selector="SplitButton:checked-flyout-open /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
   <Style Selector="SplitButton:checked-flyout-open /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
@@ -281,11 +283,11 @@
   </Style>
 
   <!-- CheckedTouchPressed State -->
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
   <Style Selector="SplitButton:checked-touch-pressed /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
@@ -304,11 +306,11 @@
   <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Rectangle#PrimaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Rectangle#SecondaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
   </Style>
   <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#PART_PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
@@ -325,11 +327,11 @@
   <Style Selector="SplitButton:checked-primary-pressed /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
   </Style>
   <Style Selector="SplitButton:checked-primary-pressed /template/ Button#PART_PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
@@ -346,11 +348,11 @@
   <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Rectangle#PrimaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Rectangle#SecondaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
   </Style>
   <Style Selector="SplitButton:checked-secondary-pointerover /template/ Button#PART_PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
@@ -367,11 +369,11 @@
   <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#Border">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Rectangle#PrimaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Rectangle#SecondaryBackgroundRectangle">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
   <Style Selector="SplitButton:checked-secondary-pressed /template/ Button#PART_PrimaryButton">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />

From 67cfbe37323fad76fb5cb43fef31d273c63ecde6 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Tue, 25 Jan 2022 23:37:12 -0500
Subject: [PATCH 27/48] Simplify style by integrating background and root
 Borders

---
 .../Controls/SplitButton.xaml                 | 35 +++++++++----------
 1 file changed, 16 insertions(+), 19 deletions(-)

diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index 0e5ccf4ec3..b05e1341bb 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -31,8 +31,12 @@
     <Setter Property="Template">
       <Setter.Value>
         <ControlTemplate>
-          <!-- A Border was added here since Avalonia does not support Background/Border/CornerRadius on Grid directly -->
-          <Border Background="Transparent"
+          <!-- A Border was added here since Avalonia does not support Background/Border/CornerRadius on Grid directly
+               This also allowed removing the extra background border and integrating it here. -->
+          <Border x:Name="RootBorder"
+                  Background="Transparent"
+                  BorderBrush="{TemplateBinding BorderBrush}"
+                  BorderThickness="{TemplateBinding BorderThickness}"
                   CornerRadius="{TemplateBinding CornerRadius}">
             <!-- In WinUI, a separate child style for the inner buttons is provided here.
                  For avalonia that style is simplified and pulled out separately below.
@@ -56,13 +60,6 @@
                       Grid.Column="2"
                       CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource RightCornerRadiusFilterConverter}}" />
 
-              <!-- Changed from Grid to Border to support Background/Border/CornerRadius properties -->
-              <Border x:Name="Border"
-                      Grid.ColumnSpan="3"
-                      BorderBrush="{TemplateBinding BorderBrush}"
-                      BorderThickness="{TemplateBinding BorderThickness}"
-                      CornerRadius="{TemplateBinding CornerRadius}" />
-
               <Button x:Name="PART_PrimaryButton"
                       Grid.Column="0"
                       Foreground="{TemplateBinding Foreground}"
@@ -148,7 +145,7 @@
   </Style>
 
   <!-- Disabled State -->
-  <Style Selector="SplitButton:disabled /template/ Border#Border">
+  <Style Selector="SplitButton:disabled /template/ Border#RootBorder">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushDisabled}" />
   </Style>
   <Style Selector="SplitButton:disabled /template/ Path#DropDownGlyphPath">
@@ -167,7 +164,7 @@
   <Style Selector="SplitButton:flyout-open /template/ Border#SecondaryBackgroundBorder">
     <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:flyout-open /template/ Border#Border">
+  <Style Selector="SplitButton:flyout-open /template/ Border#RootBorder">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
   </Style>
   <Style Selector="SplitButton:flyout-open /template/ Button#PART_PrimaryButton">
@@ -184,7 +181,7 @@
   <Style Selector="SplitButton:touch-pressed /template/ Border#SecondaryBackgroundBorder">
     <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:touch-pressed /template/ Border#Border">
+  <Style Selector="SplitButton:touch-pressed /template/ Border#RootBorder">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
   </Style>
   <Style Selector="SplitButton:touch-pressed /template/ Button#PART_PrimaryButton">
@@ -249,7 +246,7 @@
   <Style Selector="SplitButton:checked /template/ Border#SecondaryBackgroundBorder">
     <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked /template/ Border#Border">
+  <Style Selector="SplitButton:checked /template/ Border#RootBorder">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
   <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton">
@@ -269,7 +266,7 @@
   <Style Selector="SplitButton:checked-flyout-open /template/ Border#SecondaryBackgroundBorder">
     <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Border#Border">
+  <Style Selector="SplitButton:checked-flyout-open /template/ Border#RootBorder">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
   </Style>
   <Style Selector="SplitButton:checked-flyout-open /template/ Button#PART_PrimaryButton">
@@ -289,7 +286,7 @@
   <Style Selector="SplitButton:checked-touch-pressed /template/ Border#SecondaryBackgroundBorder">
     <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#Border">
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#RootBorder">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
   </Style>
   <Style Selector="SplitButton:checked-touch-pressed /template/ Button#PART_PrimaryButton">
@@ -303,7 +300,7 @@
   </Style>
 
   <!-- CheckedPrimaryPointerOver State -->
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#Border">
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#RootBorder">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
   <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#PrimaryBackgroundBorder">
@@ -324,7 +321,7 @@
   </Style>
 
   <!-- CheckedPrimaryPressed State -->
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#Border">
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#RootBorder">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
   <Style Selector="SplitButton:checked-primary-pressed /template/ Border#PrimaryBackgroundBorder">
@@ -345,7 +342,7 @@
   </Style>
 
   <!-- CheckedSecondaryPointerOver State -->
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#Border">
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#RootBorder">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
   <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#PrimaryBackgroundBorder">
@@ -366,7 +363,7 @@
   </Style>
 
   <!-- CheckedSecondaryPressed State -->
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#Border">
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#RootBorder">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
   </Style>
   <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#PrimaryBackgroundBorder">

From 8a529a6768dc0eb9f2eaa9b95e0fe304089c4361 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Wed, 26 Jan 2022 00:21:54 -0500
Subject: [PATCH 28/48] Add Default theme for SplitButton

---
 .../Controls/SplitButton.xaml                 | 430 ++++++++++++++++++
 src/Avalonia.Themes.Default/DefaultTheme.xaml |   1 +
 2 files changed, 431 insertions(+)
 create mode 100644 src/Avalonia.Themes.Default/Controls/SplitButton.xaml

diff --git a/src/Avalonia.Themes.Default/Controls/SplitButton.xaml b/src/Avalonia.Themes.Default/Controls/SplitButton.xaml
new file mode 100644
index 0000000000..a4f3e16673
--- /dev/null
+++ b/src/Avalonia.Themes.Default/Controls/SplitButton.xaml
@@ -0,0 +1,430 @@
+<Styles xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        x:CompileBindings="True">
+
+  <!-- This style is heavily based on the Fluent v1 style.
+       The base resources are switched out along with a few minor changes such as Padding, CornerRadius. -->
+
+  <Design.PreviewWith>
+    <Border Padding="20">
+      <SplitButton />
+    </Border>
+  </Design.PreviewWith>
+
+  <Styles.Resources>
+    <x:Double x:Key="SplitButtonPrimaryButtonSize">32</x:Double>
+    <GridLength x:Key="SplitButtonSecondaryButtonSize">32</GridLength>
+    <Thickness x:Key="SplitButtonBorderThemeThickness">1</Thickness>
+    
+    <StaticResource x:Key="SplitButtonBackground" ResourceKey="ThemeControlMidBrush" />
+    <StaticResource x:Key="SplitButtonBackgroundPointerOver" ResourceKey="ThemeControlMidBrush" />
+    <StaticResource x:Key="SplitButtonBackgroundPressed" ResourceKey="ThemeControlHighBrush" />
+    <SolidColorBrush x:Key="SplitButtonBackgroundDisabled" Color="{DynamicResource ThemeControlMidColor}" Opacity="{DynamicResource ThemeDisabledOpacity}" />
+    <StaticResource x:Key="SplitButtonBackgroundChecked" ResourceKey="ThemeControlHighBrush" />
+    <StaticResource x:Key="SplitButtonBackgroundCheckedPointerOver" ResourceKey="ThemeControlHighBrush" />
+    <StaticResource x:Key="SplitButtonBackgroundCheckedPressed" ResourceKey="ThemeControlHighBrush" />
+    <SolidColorBrush x:Key="SplitButtonBackgroundCheckedDisabled" Color="{DynamicResource ThemeControlHighColor}" Opacity="{DynamicResource ThemeDisabledOpacity}" />
+    
+    <StaticResource x:Key="SplitButtonForeground" ResourceKey="ThemeForegroundBrush" />
+    <StaticResource x:Key="SplitButtonForegroundPointerOver" ResourceKey="ThemeForegroundBrush" />
+    <StaticResource x:Key="SplitButtonForegroundPressed" ResourceKey="ThemeForegroundBrush" />
+    <StaticResource x:Key="SplitButtonForegroundDisabled" ResourceKey="ThemeForegroundBrush" />
+    <StaticResource x:Key="SplitButtonForegroundChecked" ResourceKey="ThemeForegroundBrush" />
+    <StaticResource x:Key="SplitButtonForegroundCheckedPointerOver" ResourceKey="ThemeForegroundBrush" />
+    <StaticResource x:Key="SplitButtonForegroundCheckedPressed" ResourceKey="ThemeForegroundBrush" />
+    <StaticResource x:Key="SplitButtonForegroundCheckedDisabled" ResourceKey="ThemeForegroundBrush" />
+
+    <StaticResource x:Key="SplitButtonBorderBrush" ResourceKey="ThemeBorderLowBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushPointerOver" ResourceKey="ThemeBorderMidBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushPressed" ResourceKey="ThemeBorderLowBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushDisabled" ResourceKey="ThemeBorderLowBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushChecked" ResourceKey="ThemeBorderMidBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushCheckedPointerOver" ResourceKey="ThemeBorderMidBrush" />
+    <StaticResource x:Key="SplitButtonBorderBrushCheckedPressed" ResourceKey="ThemeControlHighBrush" />
+    <SolidColorBrush x:Key="SplitButtonBorderBrushCheckedDisabled" Color="{DynamicResource ThemeControlMidColor}" Opacity="{DynamicResource ThemeDisabledOpacity}" />
+  </Styles.Resources>
+
+  <Style Selector="SplitButton">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForeground}" />
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrush}" />
+    <Setter Property="BorderThickness" Value="{DynamicResource SplitButtonBorderThemeThickness}" />
+    <Setter Property="HorizontalAlignment" Value="Left" />
+    <Setter Property="VerticalAlignment" Value="Center" />
+    <!--<Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}" />
+    <Setter Property="FontWeight" Value="Normal" />
+    <Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}" />
+    <Setter Property="UseSystemFocusVisuals" Value="True" />
+    <Setter Property="FocusVisualMargin" Value="-3" />-->
+    <Setter Property="KeyboardNavigation.IsTabStop" Value="True" />
+    <Setter Property="Padding" Value="4" />
+    <Setter Property="CornerRadius" Value="0" />
+    <Setter Property="Template">
+      <Setter.Value>
+        <ControlTemplate>
+          <!-- A Border was added here since Avalonia does not support Background/Border/CornerRadius on Grid directly
+               This also allowed removing the extra background border and integrating it here. -->
+          <Border x:Name="RootBorder"
+                  Background="Transparent"
+                  BorderBrush="{TemplateBinding BorderBrush}"
+                  BorderThickness="{TemplateBinding BorderThickness}"
+                  CornerRadius="{TemplateBinding CornerRadius}">
+            <!-- In WinUI, a separate child style for the inner buttons is provided here.
+                 For avalonia that style is simplified and pulled out separately below.
+                 A style is needed to override any button default background/foreground/border colors, etc. -->
+            <Grid>
+              
+              <Grid.ColumnDefinitions>
+                <ColumnDefinition Width="*"
+                                  MinWidth="{StaticResource SplitButtonPrimaryButtonSize}" />
+                <ColumnDefinition Width="1" />
+                <ColumnDefinition Width="{StaticResource SplitButtonSecondaryButtonSize}" />
+              </Grid.ColumnDefinitions>
+
+              <!-- Changed from Grid to Border since Avalonia does not support Background/CornerRadius on Grid directly -->
+              <Border x:Name="PrimaryBackgroundBorder"
+                      Background="{TemplateBinding Background}"
+                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource LeftCornerRadiusFilterConverter}}" />
+
+              <Border x:Name="SecondaryBackgroundBorder"
+                      Background="{TemplateBinding Background}"
+                      Grid.Column="2"
+                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource RightCornerRadiusFilterConverter}}" />
+
+              <Button x:Name="PART_PrimaryButton"
+                      Grid.Column="0"
+                      Foreground="{TemplateBinding Foreground}"
+                      Background="{TemplateBinding Background}"
+                      BorderThickness="{TemplateBinding BorderThickness}"
+                      BorderBrush="Transparent"
+                      Content="{TemplateBinding Content}"
+                      ContentTemplate="{TemplateBinding ContentTemplate}"
+                      Command="{TemplateBinding Command}"
+                      CommandParameter="{TemplateBinding CommandParameter}"
+                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource LeftCornerRadiusFilterConverter}}"
+                      FontFamily="{TemplateBinding FontFamily}"
+                      FontSize="{TemplateBinding FontSize}"
+                      FontWeight="{TemplateBinding FontWeight}"
+                      HorizontalAlignment="Stretch"
+                      VerticalAlignment="Stretch"
+                      HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                      VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
+                      Padding="{TemplateBinding Padding}"
+                      KeyboardNavigation.IsTabStop="False" />
+
+              <Button x:Name="PART_SecondaryButton"
+                      Grid.Column="2"
+                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource RightCornerRadiusFilterConverter}}"
+                      Foreground="{TemplateBinding Foreground}"
+                      Background="{TemplateBinding Background}"
+                      BorderThickness="{TemplateBinding BorderThickness}"
+                      BorderBrush="Transparent"
+                      HorizontalContentAlignment="Right"
+                      VerticalContentAlignment="Center"
+                      HorizontalAlignment="Stretch"
+                      VerticalAlignment="Stretch"
+                      KeyboardNavigation.IsTabStop="False"
+                      Padding="0,0,10,0">
+                <Button.Content>
+                  <!-- TextBlock converted to a Path and placed within Viewbox -->
+                  <Viewbox UseLayoutRounding="False"
+                           IsHitTestVisible="False"
+                           Height="12"
+                           Width="12">
+                    <Path x:Name="DropDownGlyphPath"
+                          VerticalAlignment="Center"
+                          HorizontalAlignment="Right"
+                          Fill="{TemplateBinding Foreground}"
+                          Data="M1939 486L2029 576L1024 1581L19 576L109 486L1024 1401L1939 486Z"
+                          Stretch="Uniform" />
+                  </Viewbox>
+                </Button.Content>
+              </Button>
+            </Grid>
+          </Border>
+        </ControlTemplate>
+      </Setter.Value>
+    </Setter>
+  </Style>
+
+  <!-- Normal State (not a PseudoClass) -->
+  <!-- The 'Button' style here was moved out of the main style above.
+       In WinUI there is a child, customized style shared for both primary and secondary buttons.
+       In Avalonia, we can use selectors to make a 'normal' style apply only to those buttons but
+       pull it out separately from the full style above. -->
+  <Style Selector="SplitButton /template/ Button">
+    <!-- Applies to both Primary/Secondary buttons -->
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForeground}" />
+    <Setter Property="BorderBrush" Value="Transparent" />
+    <Setter Property="BorderThickness" Value="{DynamicResource SplitButtonBorderThemeThickness}" />
+    <Setter Property="Template">
+      <ControlTemplate>
+        <!-- Switched from Grid to Border to optimize and support Foreground/Background properties -->
+        <!-- It is important for the background to be clear and no CornerRadius set. -->
+        <Border Background="Transparent">
+          <ContentPresenter x:Name="ContentPresenter"
+                            BorderBrush="{TemplateBinding BorderBrush}"
+                            BorderThickness="{TemplateBinding BorderThickness}"
+                            Content="{TemplateBinding Content}"
+                            ContentTemplate="{TemplateBinding ContentTemplate}"
+                            Padding="{TemplateBinding Padding}"
+                            HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                            VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" />
+        </Border>
+      </ControlTemplate>
+    </Setter>
+  </Style>
+
+  <!-- Disabled State -->
+  <Style Selector="SplitButton:disabled /template/ Border#RootBorder">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushDisabled}" />
+  </Style>
+  <Style Selector="SplitButton:disabled /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundDisabled}" />
+  </Style>
+  <Style Selector="SplitButton:disabled /template/ Button">
+    <!-- Applies to both Primary/Secondary buttons -->
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundDisabled}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundDisabled}" />
+  </Style>
+
+  <!-- FlyoutOpen State -->
+  <Style Selector="SplitButton:flyout-open /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:flyout-open /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:flyout-open /template/ Border#RootBorder">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+  </Style>
+  <Style Selector="SplitButton:flyout-open /template/ Button#PART_PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:flyout-open /template/ Button#PART_SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+
+  <!-- TouchPressed State -->
+  <Style Selector="SplitButton:touch-pressed /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:touch-pressed /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:touch-pressed /template/ Border#RootBorder">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+  </Style>
+  <Style Selector="SplitButton:touch-pressed /template/ Button#PART_PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:touch-pressed /template/ Button#PART_SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+
+  <!-- PrimaryPointerOver State -->
+  <Style Selector="SplitButton:primary-pointerover /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:primary-pointerover /template/ Button#PART_PrimaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:primary-pointerover /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
+  </Style>
+
+  <!-- PrimaryPressed State -->
+  <Style Selector="SplitButton:primary-pressed /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:primary-pressed /template/ Button#PART_PrimaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:primary-pressed /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
+  </Style>
+
+  <!-- SecondaryPointerOver State -->
+  <Style Selector="SplitButton:secondary-pointerover /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
+  </Style>
+  <Style Selector="SplitButton:secondary-pointerover /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:secondary-pointerover /template/ Button#PART_SecondaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
+  </Style>
+
+  <!-- SecondaryPressed State -->
+  <Style Selector="SplitButton:secondary-pressed /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
+  </Style>
+  <Style Selector="SplitButton:secondary-pressed /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:secondary-pressed /template/ Button#PART_SecondaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+
+  <!-- Checked State -->
+  <Style Selector="SplitButton:checked /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked /template/ Border#RootBorder">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
+
+  <!-- CheckedFlyoutOpen State -->
+  <Style Selector="SplitButton:checked-flyout-open /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-flyout-open /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-flyout-open /template/ Border#RootBorder">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-flyout-open /template/ Button#PART_PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-flyout-open /template/ Button#PART_SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-flyout-open /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+
+  <!-- CheckedTouchPressed State -->
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#RootBorder">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Button#PART_PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Button#PART_SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-touch-pressed /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+
+  <!-- CheckedPrimaryPointerOver State -->
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#RootBorder">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#PART_PrimaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#PART_SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked-primary-pointerover /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
+
+  <!-- CheckedPrimaryPressed State -->
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#RootBorder">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Button#PART_PrimaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Button#PART_SecondaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked-primary-pressed /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
+
+  <!-- CheckedSecondaryPointerOver State -->
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#RootBorder">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Button#PART_PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Button#PART_SecondaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
+  </Style>
+
+  <!-- CheckedSecondaryPressed State -->
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#RootBorder">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#PrimaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#SecondaryBackgroundBorder">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Button#PART_PrimaryButton">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Button#PART_SecondaryButton">
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked-secondary-pressed /template/ Path#DropDownGlyphPath">
+    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+
+  <!-- SecondaryButtonPlacement States -->
+  <!-- Note: Setting Grid attached properties doesn't work here for some unknown reason.
+       They simply are never changed. In addition, touch-device changes of secondary button
+       size are currently disabled in code-behind. -->
+  <Style Selector="SplitButton:secondary-button-right /template/ Button#PART_SecondaryButton">
+    <Setter Property="(Grid.Column)" Value="2" />
+    <Setter Property="(Grid.ColumnSpan)" Value="1" />
+  </Style>
+  <Style Selector="SplitButton:secondary-button-span /template/ Button#PART_SecondaryButton">
+    <Setter Property="(Grid.Column)" Value="0" />
+    <Setter Property="(Grid.ColumnSpan)" Value="3" />
+  </Style>
+
+</Styles>
diff --git a/src/Avalonia.Themes.Default/DefaultTheme.xaml b/src/Avalonia.Themes.Default/DefaultTheme.xaml
index 702fcc7c7a..009b56852a 100644
--- a/src/Avalonia.Themes.Default/DefaultTheme.xaml
+++ b/src/Avalonia.Themes.Default/DefaultTheme.xaml
@@ -57,6 +57,7 @@
   <StyleInclude Source="avares://Avalonia.Themes.Default/Controls/NotificationCard.xaml"/>
   <StyleInclude Source="avares://Avalonia.Themes.Default/Controls/NativeMenuBar.xaml"/>
   <StyleInclude Source="avares://Avalonia.Themes.Default/Controls/ToggleSwitch.xaml"/>
+  <StyleInclude Source="avares://Avalonia.Themes.Default/Controls/SplitButton.xaml" />
   <StyleInclude Source="avares://Avalonia.Themes.Default/Controls/SplitView.xaml"/>
   <StyleInclude Source="avares://Avalonia.Themes.Default/Controls/DatePicker.xaml"/>
   <StyleInclude Source="avares://Avalonia.Themes.Default/Controls/TimePicker.xaml"/>

From aaf5282ebd6f06b88678649faf90ce1e616344ca Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Wed, 26 Jan 2022 01:19:57 -0500
Subject: [PATCH 29/48] Integrate all button controls within a redesigned
 ButtonsPage

---
 samples/ControlCatalog/MainView.xaml          |   7 +-
 samples/ControlCatalog/Pages/ButtonPage.xaml  |  45 ----
 samples/ControlCatalog/Pages/ButtonsPage.xaml | 201 ++++++++++++++++++
 ...ButtonPage.xaml.cs => ButtonsPage.xaml.cs} |   4 +-
 .../ControlCatalog/Pages/SplitButtonPage.xaml |  40 ----
 .../Pages/SplitButtonPage.xaml.cs             |  18 --
 .../Pages/ToggleSwitchPage.xaml               |   2 +-
 7 files changed, 206 insertions(+), 111 deletions(-)
 delete mode 100644 samples/ControlCatalog/Pages/ButtonPage.xaml
 create mode 100644 samples/ControlCatalog/Pages/ButtonsPage.xaml
 rename samples/ControlCatalog/Pages/{ButtonPage.xaml.cs => ButtonsPage.xaml.cs} (90%)
 delete mode 100644 samples/ControlCatalog/Pages/SplitButtonPage.xaml
 delete mode 100644 samples/ControlCatalog/Pages/SplitButtonPage.xaml.cs

diff --git a/samples/ControlCatalog/MainView.xaml b/samples/ControlCatalog/MainView.xaml
index a4246e946a..7beb496ab5 100644
--- a/samples/ControlCatalog/MainView.xaml
+++ b/samples/ControlCatalog/MainView.xaml
@@ -22,8 +22,8 @@
       <TabItem Header="Border">
         <pages:BorderPage />
       </TabItem>
-      <TabItem Header="Button">
-        <pages:ButtonPage />
+      <TabItem Header="Buttons">
+        <pages:ButtonsPage />
       </TabItem>
       <TabItem Header="ButtonSpinner">
         <pages:ButtonSpinnerPage />
@@ -121,9 +121,6 @@
       <TabItem Header="Slider">
         <pages:SliderPage />
       </TabItem>
-      <TabItem Header="SplitButton">
-        <pages:SplitButtonPage />
-      </TabItem>
       <TabItem Header="SplitView">
         <pages:SplitViewPage />
       </TabItem>
diff --git a/samples/ControlCatalog/Pages/ButtonPage.xaml b/samples/ControlCatalog/Pages/ButtonPage.xaml
deleted file mode 100644
index 2ce1469118..0000000000
--- a/samples/ControlCatalog/Pages/ButtonPage.xaml
+++ /dev/null
@@ -1,45 +0,0 @@
-<UserControl xmlns="https://github.com/avaloniaui"
-             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             x:Class="ControlCatalog.Pages.ButtonPage">
-  <StackPanel Orientation="Vertical" Spacing="4">
-    <TextBlock Classes="h2">A button control</TextBlock>
-
-    <StackPanel Orientation="Horizontal"
-                Margin="0,16,0,0"
-                HorizontalAlignment="Center"
-                Spacing="16">
-      <StackPanel Orientation="Vertical" Spacing="8" Width="200">
-        <Button>Standard _XAML Button</Button>
-        <Button Foreground="White">Foreground</Button>
-        <Button Background="{DynamicResource SystemAccentColor}">Background</Button>
-        <Button IsEnabled="False">Disabled</Button>
-        <Button Content="Re-themed">
-          <Button.Styles>
-            <Style>
-              <Style.Resources>
-                <SolidColorBrush x:Key="ThemeBorderMidBrush">Red</SolidColorBrush>
-                <SolidColorBrush x:Key="ThemeControlHighBrush">DarkRed</SolidColorBrush>
-                <SolidColorBrush x:Key="ButtonBorderBrush">Red</SolidColorBrush>
-                <SolidColorBrush x:Key="ButtonBackground">DarkRed</SolidColorBrush>
-                <SolidColorBrush x:Key="ButtonBackgroundPointerOver">Red</SolidColorBrush>
-                <SolidColorBrush x:Key="ButtonBackgroundPressed">OrangeRed</SolidColorBrush>
-              </Style.Resources>
-            </Style>
-          </Button.Styles>          
-        </Button>
-        <RepeatButton Name="RepeatButton">
-          <TextBlock Name="RepeatButtonTextBlock" Text="Repeat Button: 0" />
-        </RepeatButton>
-        <ToggleButton Content="Toggle Button"/>
-    </StackPanel>
-
-      <StackPanel Orientation="Vertical" Spacing="8" Width="150">
-        <Button BorderThickness="0">No Border</Button>
-        <Button BorderBrush="{DynamicResource SystemAccentColor}">Border Color</Button>
-        <Button BorderBrush="{DynamicResource SystemAccentColor}" BorderThickness="4">Thick Border</Button>
-        <Button BorderBrush="{DynamicResource SystemAccentColor}" BorderThickness="4" IsEnabled="False">Disabled</Button>
-        <Button BorderBrush="{DynamicResource SystemAccentColor}" KeyboardNavigation.IsTabStop="False">IsTabStop=False</Button>
-      </StackPanel>
-    </StackPanel>    
-  </StackPanel>
-</UserControl>
diff --git a/samples/ControlCatalog/Pages/ButtonsPage.xaml b/samples/ControlCatalog/Pages/ButtonsPage.xaml
new file mode 100644
index 0000000000..e2d1010859
--- /dev/null
+++ b/samples/ControlCatalog/Pages/ButtonsPage.xaml
@@ -0,0 +1,201 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             x:Class="ControlCatalog.Pages.ButtonsPage">
+
+  <UserControl.Resources>
+
+    <MenuFlyout x:Key="SharedMenuFlyout"
+                Placement="Bottom">
+      <MenuItem Header="Item 1">
+        <MenuItem Header="Subitem 1" />
+        <MenuItem Header="Subitem 2" />
+        <MenuItem Header="Subitem 3" />
+      </MenuItem>
+      <MenuItem Header="Item 2"
+                InputGesture="Ctrl+A" />
+      <MenuItem Header="Item 3" />
+    </MenuFlyout>
+
+  </UserControl.Resources>
+      
+  <UserControl.Styles >
+
+    <Style Selector="Border.header-border">
+      <Setter Property="Background">
+        <Setter.Value>
+          <SolidColorBrush Color="Gray" Opacity="0.5" />
+        </Setter.Value>
+      </Setter>
+      <Setter Property="BorderBrush" Value="Gray" />
+      <Setter Property="BorderThickness" Value="0.5" />
+      <Setter Property="CornerRadius" Value="5,5,0,0" />
+      <Setter Property="MaxWidth" Value="450" />
+      <Setter Property="Padding" Value="10" />
+    </Style>
+    
+    <Style Selector="TextBlock.header">
+      <Setter Property="FontSize" Value="18" />
+      <Setter Property="FontWeight" Value="Bold" />
+    </Style>
+
+    <Style Selector="Border.thin">
+      <Setter Property="BorderBrush" Value="Gray" />
+      <Setter Property="BorderThickness" Value="0.5" />
+      <Setter Property="CornerRadius" Value="0,0,5,5" />
+      <Setter Property="Margin" Value="0,0,0,15" />
+    </Style>
+
+  </UserControl.Styles>
+
+  <!-- Styles and overall page design based on AcrylicPage -->
+
+  <StackPanel Orientation="Vertical"
+              Width="450">
+
+    <!-- Button -->
+    <Border Classes="header-border">
+      <StackPanel Orientation="Vertical"
+                  Spacing="4">
+        <TextBlock Text="Button" Classes="header" />
+        <TextBlock TextWrapping="Wrap">A standard button control</TextBlock>
+      </StackPanel>
+    </Border>
+
+    <Border Classes="thin"
+            Padding="15">
+      <StackPanel Orientation="Horizontal"
+                  HorizontalAlignment="Center"
+                  Spacing="10">
+        <StackPanel Orientation="Vertical"
+                    Spacing="8"
+                    Width="200">
+          <Button>Standard _XAML Button</Button>
+          <Button Foreground="White">Foreground</Button>
+          <Button Background="{DynamicResource SystemAccentColor}">Background</Button>
+          <Button IsEnabled="False">Disabled</Button>
+          <Button Content="Re-themed">
+            <Button.Styles>
+              <Style>
+                <Style.Resources>
+                  <SolidColorBrush x:Key="ThemeBorderMidBrush">Red</SolidColorBrush>
+                  <SolidColorBrush x:Key="ThemeControlHighBrush">DarkRed</SolidColorBrush>
+                  <SolidColorBrush x:Key="ButtonBorderBrush">Red</SolidColorBrush>
+                  <SolidColorBrush x:Key="ButtonBackground">DarkRed</SolidColorBrush>
+                  <SolidColorBrush x:Key="ButtonBackgroundPointerOver">Red</SolidColorBrush>
+                  <SolidColorBrush x:Key="ButtonBackgroundPressed">OrangeRed</SolidColorBrush>
+                </Style.Resources>
+              </Style>
+            </Button.Styles>
+          </Button>
+        </StackPanel>
+
+        <StackPanel Orientation="Vertical"
+                    Spacing="8"
+                    Width="200">
+          <Button BorderThickness="0">No Border</Button>
+          <Button BorderBrush="{DynamicResource SystemAccentColor}">Border Color</Button>
+          <Button BorderBrush="{DynamicResource SystemAccentColor}"
+                  BorderThickness="4">Thick Border</Button>
+          <Button BorderBrush="{DynamicResource SystemAccentColor}"
+                  BorderThickness="4"
+                  IsEnabled="False">Disabled</Button>
+          <Button BorderBrush="{DynamicResource SystemAccentColor}"
+                  KeyboardNavigation.IsTabStop="False">IsTabStop=False</Button>
+        </StackPanel>
+      </StackPanel>
+    </Border>
+
+    <!-- ToggleButton -->
+    <Border Classes="header-border">
+      <StackPanel Orientation="Vertical"
+                  Spacing="4">
+        <TextBlock Text="ToggleButton"
+                   Classes="header" />
+        <TextBlock TextWrapping="Wrap">A button control with multiple states: checked, unchecked or indeterminate.</TextBlock>
+      </StackPanel>
+    </Border>
+
+    <Border Classes="thin"
+            Padding="15">
+      <StackPanel Orientation="Vertical"
+                  Spacing="8">
+        <ToggleButton Content="Toggle Button" />
+      </StackPanel>
+    </Border>
+
+    <!-- RepeatButton -->
+    <Border Classes="header-border">
+      <StackPanel Orientation="Vertical"
+                  Spacing="4">
+        <TextBlock Text="RepeatButton"
+                   Classes="header" />
+        <TextBlock TextWrapping="Wrap">A button control that raises its Click event repeatedly when it is pressed and held.</TextBlock>
+      </StackPanel>
+    </Border>
+
+    <Border Classes="thin"
+            Padding="15">
+      <StackPanel Orientation="Vertical"
+                  Spacing="8">
+        <RepeatButton Name="RepeatButton">
+          <TextBlock Name="RepeatButtonTextBlock"
+                     Text="Repeat Button: 0" />
+        </RepeatButton>
+      </StackPanel>
+    </Border>
+
+    <!-- SplitButton -->
+    <Border Classes="header-border">
+      <StackPanel Orientation="Vertical"
+                  Spacing="4">
+        <TextBlock Text="SplitButton"
+                   Classes="header" />
+        <TextBlock TextWrapping="Wrap">A button with primary and secondary parts that can each be pressed separately. The primary part behaves like a Button and the secondary part opens a flyout.</TextBlock>
+      </StackPanel>
+    </Border>
+
+    <Border Classes="thin"
+            Padding="15">
+      <StackPanel Orientation="Vertical"
+                  Spacing="8">
+        <SplitButton Flyout="{StaticResource SharedMenuFlyout}">
+          <TextBlock Text="Content" />
+        </SplitButton>
+        <SplitButton IsEnabled="False"
+                     Flyout="{StaticResource SharedMenuFlyout}">
+          <TextBlock Text="Disabled" />
+        </SplitButton>
+      </StackPanel>
+    </Border>
+
+    <!-- ToggleSplitButton -->
+    <Border Classes="header-border">
+      <StackPanel Orientation="Vertical"
+                  Spacing="4">
+        <TextBlock Text="ToggleSplitButton"
+                   Classes="header" />
+        <TextBlock TextWrapping="Wrap">A button with primary and secondary parts that can each be pressed separately. The primary part behaves like a ToggleButton with two states and the secondary part opens a flyout.</TextBlock>
+      </StackPanel>
+    </Border>
+
+    <Border Classes="thin"
+            Padding="15">
+      <StackPanel Orientation="Vertical"
+                  Spacing="8">
+        <ToggleSplitButton Flyout="{StaticResource SharedMenuFlyout}">
+          <TextBlock Text="Content" />
+        </ToggleSplitButton>
+        <ToggleSplitButton IsChecked="True"
+                           Flyout="{StaticResource SharedMenuFlyout}">
+          <TextBlock Text="Content" />
+        </ToggleSplitButton>
+        <ToggleSplitButton IsChecked="True"
+                           IsEnabled="False"
+                           Flyout="{StaticResource SharedMenuFlyout}">
+          <TextBlock Text="Disabled" />
+        </ToggleSplitButton>
+      </StackPanel>
+    </Border>
+
+  </StackPanel>
+</UserControl>
diff --git a/samples/ControlCatalog/Pages/ButtonPage.xaml.cs b/samples/ControlCatalog/Pages/ButtonsPage.xaml.cs
similarity index 90%
rename from samples/ControlCatalog/Pages/ButtonPage.xaml.cs
rename to samples/ControlCatalog/Pages/ButtonsPage.xaml.cs
index 5e555c8c91..5594bab176 100644
--- a/samples/ControlCatalog/Pages/ButtonPage.xaml.cs
+++ b/samples/ControlCatalog/Pages/ButtonsPage.xaml.cs
@@ -3,11 +3,11 @@ using Avalonia.Markup.Xaml;
 
 namespace ControlCatalog.Pages
 {
-    public class ButtonPage : UserControl
+    public class ButtonsPage : UserControl
     {
         private int repeatButtonClickCount = 0;
 
-        public ButtonPage()
+        public ButtonsPage()
         {
             InitializeComponent();
 
diff --git a/samples/ControlCatalog/Pages/SplitButtonPage.xaml b/samples/ControlCatalog/Pages/SplitButtonPage.xaml
deleted file mode 100644
index e530920dab..0000000000
--- a/samples/ControlCatalog/Pages/SplitButtonPage.xaml
+++ /dev/null
@@ -1,40 +0,0 @@
-<UserControl xmlns="https://github.com/avaloniaui"
-             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             x:Class="ControlCatalog.Pages.SplitButtonPage">
-
-  <UserControl.Resources>
-    <MenuFlyout x:Key="SharedMenuFlyout"
-                Placement="Bottom">
-      <MenuItem Header="Item 1">
-        <MenuItem Header="Subitem 1" />
-        <MenuItem Header="Subitem 2" />
-        <MenuItem Header="Subitem 3" />
-      </MenuItem>
-      <MenuItem Header="Item 2"
-                InputGesture="Ctrl+A" />
-      <MenuItem Header="Item 3" />
-    </MenuFlyout>
-  </UserControl.Resources>
-
-  <StackPanel Orientation="Vertical" Spacing="4">
-    <SplitButton Flyout="{StaticResource SharedMenuFlyout}">
-      <TextBlock Text="Content" />
-    </SplitButton>
-    <SplitButton IsEnabled="False"
-                 Flyout="{StaticResource SharedMenuFlyout}">
-      <TextBlock Text="Content" />
-    </SplitButton>
-    <ToggleSplitButton Flyout="{StaticResource SharedMenuFlyout}">
-      <TextBlock Text="Content" />
-    </ToggleSplitButton>
-    <ToggleSplitButton IsChecked="True"
-                       Flyout="{StaticResource SharedMenuFlyout}">
-      <TextBlock Text="Content" />
-    </ToggleSplitButton>
-    <ToggleSplitButton IsChecked="True"
-                       IsEnabled="False"
-                       Flyout="{StaticResource SharedMenuFlyout}">
-      <TextBlock Text="Content" />
-    </ToggleSplitButton>
-  </StackPanel>
-</UserControl>
diff --git a/samples/ControlCatalog/Pages/SplitButtonPage.xaml.cs b/samples/ControlCatalog/Pages/SplitButtonPage.xaml.cs
deleted file mode 100644
index 64b686008f..0000000000
--- a/samples/ControlCatalog/Pages/SplitButtonPage.xaml.cs
+++ /dev/null
@@ -1,18 +0,0 @@
-using Avalonia.Controls;
-using Avalonia.Markup.Xaml;
-
-namespace ControlCatalog.Pages
-{
-    public class SplitButtonPage : UserControl
-    {
-        public SplitButtonPage()
-        {
-            InitializeComponent();
-        }
-
-        private void InitializeComponent()
-        {
-            AvaloniaXamlLoader.Load(this);
-        }
-    }
-}
diff --git a/samples/ControlCatalog/Pages/ToggleSwitchPage.xaml b/samples/ControlCatalog/Pages/ToggleSwitchPage.xaml
index 4db755b6fc..6afe6dd135 100644
--- a/samples/ControlCatalog/Pages/ToggleSwitchPage.xaml
+++ b/samples/ControlCatalog/Pages/ToggleSwitchPage.xaml
@@ -11,7 +11,7 @@
       </StackPanel>
     </Border>
 
-    <TextBlock Text="headered ToggleSwitch" Classes="header"/>
+    <TextBlock Text="Headered ToggleSwitch" Classes="header"/>
 
     <Border Classes="Thin">
       <StackPanel>

From 07e2952750698b676a1e0b22ccdc5bb19d336db2 Mon Sep 17 00:00:00 2001
From: Max Katz <maxkatz6@outlook.com>
Date: Wed, 26 Jan 2022 01:59:59 -0500
Subject: [PATCH 30/48] SplitButton Avoid unnecessary pseudoclasses by using
 Avalonia-friendly approaches

---
 .../SplitButton/SplitButton.cs                | 291 +----------
 .../SplitButton/ToggleSplitButton.cs          |   6 +-
 .../Controls/SplitButton.xaml                 | 450 +++++-------------
 3 files changed, 139 insertions(+), 608 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index 5b85a19b8a..13d3572975 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -1,5 +1,4 @@
 using System;
-using System.Reactive.Disposables;
 using System.Windows.Input;
 using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
@@ -13,45 +12,11 @@ namespace Avalonia.Controls
     /// A button with primary and secondary parts that can each be pressed separately.
     /// The primary part behaves like a <see cref="Button"/> and the secondary part opens a flyout.
     /// </summary>
-    [PseudoClasses(
-        pcDisabled,
-        pcSecondaryButtonRight,
-        pcSecondaryButtonSpan,
-        pcCheckedFlyoutOpen,
-        pcFlyoutOpen,
-        pcCheckedTouchPressed,
-        pcChecked,
-        pcCheckedPrimaryPressed,
-        pcCheckedPrimaryPointerOver,
-        pcCheckedSecondaryPressed,
-        pcCheckedSecondaryPointerOver,
-        pcTouchPressed,
-        pcPrimaryPressed,
-        pcPrimaryPointerOver,
-        pcSecondaryPressed,
-        pcSecondaryPointerOver)]
+    [PseudoClasses(pcFlyoutOpen)]
     public class SplitButton : ContentControl, ICommandSource
     {
-        private const string pcDisabled = ":disabled";
-
-        private const string pcSecondaryButtonRight = ":secondary-button-right";
-        private const string pcSecondaryButtonSpan  = ":secondary-button-span";
-
-        private const string pcCheckedFlyoutOpen = ":checked-flyout-open";
         private const string pcFlyoutOpen        = ":flyout-open";
-
-        private const string pcCheckedTouchPressed         = ":checked-touch-pressed";
-        private const string pcChecked                     = ":checked";
-        private const string pcCheckedPrimaryPressed       = ":checked-primary-pressed";
-        private const string pcCheckedPrimaryPointerOver   = ":checked-primary-pointerover";
-        private const string pcCheckedSecondaryPressed     = ":checked-secondary-pressed";
-        private const string pcCheckedSecondaryPointerOver = ":checked-secondary-pointerover";
-
-        private const string pcTouchPressed         = ":touch-pressed";
-        private const string pcPrimaryPressed       = ":primary-pressed";
-        private const string pcPrimaryPointerOver   = ":primary-pointerover";
-        private const string pcSecondaryPressed     = ":secondary-pressed";
-        private const string pcSecondaryPointerOver = ":secondary-pointerover";
+        protected const string pcChecked = ":checked";
 
         /// <summary>
         /// Raised when the user presses the primary part of the <see cref="SplitButton"/>.
@@ -62,13 +27,7 @@ namespace Avalonia.Controls
             remove => RemoveHandler(ClickEvent, value);
         }
 
-        /// <summary>
-        /// Defines the <see cref="Click"/> event.
-        /// </summary>
-        public static readonly RoutedEvent<RoutedEventArgs> ClickEvent =
-            RoutedEvent.Register<SplitButton, RoutedEventArgs>(
-                nameof(Click),
-                RoutingStrategies.Bubble);
+        public static readonly RoutedEvent<RoutedEventArgs> ClickEvent = Button.ClickEvent;
 
         /// <summary>
         /// Defines the <see cref="Command"/> property.
@@ -96,13 +55,9 @@ namespace Avalonia.Controls
         private Button _secondaryButton = null;
 
         private bool        _commandCanExecute       = true;
-        protected bool      _hasLoaded               = false;
         private bool        _isAttachedToLogicalTree = false;
         private bool        _isFlyoutOpen            = false;
-        private bool        _isKeyDown               = false;
-        private PointerType _lastPointerType         = PointerType.Mouse;
 
-        private CompositeDisposable _buttonPropertyChangedDisposable;
         private IDisposable         _flyoutPropertyChangedDisposable;
 
         ////////////////////////////////////////////////////////////////////////
@@ -181,152 +136,8 @@ namespace Avalonia.Controls
         /// </summary>
         protected void UpdatePseudoClasses()
         {
-            // Place the secondary button
-            //
-            // In WinUI, the span of the secondary button is changed to full-width for touch-based
-            // devices in certain conditions. The full reasoning for this is unknown. Some theories
-            // include:
-            //
-            //   My guess is that the design team at MS decided that it's a better experience
-            //   for touch users to make them select from the drop down rather than the shortcut
-            //   top level button, so touch basically just turns this into a drop down button.
-            //   Whether that's ideal or not is going is a subjective opinion.
-            //
-            // For Avalonia, it may not always make sense to disable the primary button like that
-            // on touch-first platforms. Users and developers would normally expect a control to
-            // function the same on all platforms. Therefore, this functionality is disabled here
-            // but could be re-enabled in the future if more reasons become known.
-            //
-            // Finally, these are mutually exclusive PseudoClasses handled separately from
-            // SetExclusivePseudoClass(). They must be applied in addition to the others.
-            /*
-            if (_lastPointerType == PointerType.Touch || _isKeyDown)
-            {
-                PseudoClasses.Set(pcSecondaryButtonSpan, true);
-                PseudoClasses.Set(pcSecondaryButtonRight, false);
-            }
-            else
-            {
-                PseudoClasses.Set(pcSecondaryButtonSpan, false);
-                PseudoClasses.Set(pcSecondaryButtonRight, true);
-            }
-            */
-
-            // Change the visual state
-            if (!IsEffectivelyEnabled)
-            {
-                SetExclusivePseudoClass(pcDisabled);
-            }
-            else if (_primaryButton != null && _secondaryButton != null)
-            {
-                if (_isFlyoutOpen)
-                {
-                    if (InternalIsChecked)
-                    {
-                        SetExclusivePseudoClass(pcCheckedFlyoutOpen);
-                    }
-                    else
-                    {
-                        SetExclusivePseudoClass(pcFlyoutOpen);
-                    }
-                }
-                // SplitButton and ToggleSplitButton share a template -- this section is driving the checked states for ToggleSplitButton.
-                else if (InternalIsChecked)
-                {
-                    if (_lastPointerType == PointerType.Touch || _isKeyDown)
-                    {
-                        if (_primaryButton.IsPressed || _secondaryButton.IsPressed || _isKeyDown)
-                        {
-                            SetExclusivePseudoClass(pcCheckedTouchPressed);
-                        }
-                        else
-                        {
-                            SetExclusivePseudoClass(pcChecked);
-                        }
-                    }
-                    else if (_primaryButton.IsPressed)
-                    {
-                        SetExclusivePseudoClass(pcCheckedPrimaryPressed);
-                    }
-                    else if (_primaryButton.IsPointerOver)
-                    {
-                        SetExclusivePseudoClass(pcCheckedPrimaryPointerOver);
-                    }
-                    else if (_secondaryButton.IsPressed)
-                    {
-                        SetExclusivePseudoClass(pcCheckedSecondaryPressed);
-                    }
-                    else if (_secondaryButton.IsPointerOver)
-                    {
-                        SetExclusivePseudoClass(pcCheckedSecondaryPointerOver);
-                    }
-                    else
-                    {
-                        SetExclusivePseudoClass(pcChecked);
-                    }
-                }
-                else
-                {
-                    if (_lastPointerType == PointerType.Touch || _isKeyDown)
-                    {
-                        if (_primaryButton.IsPressed || _secondaryButton.IsPressed || _isKeyDown)
-                        {
-                            SetExclusivePseudoClass(pcTouchPressed);
-                        }
-                        else
-                        {
-                            // Calling without a parameter is treated as ':normal' and will clear all other
-                            // PseudoClasses returning to the default state
-                            SetExclusivePseudoClass();
-                        }
-                    }
-                    else if (_primaryButton.IsPressed)
-                    {
-                        SetExclusivePseudoClass(pcPrimaryPressed);
-                    }
-                    else if (_primaryButton.IsPointerOver)
-                    {
-                        SetExclusivePseudoClass(pcPrimaryPointerOver);
-                    }
-                    else if (_secondaryButton.IsPressed)
-                    {
-                        SetExclusivePseudoClass(pcSecondaryPressed);
-                    }
-                    else if (_secondaryButton.IsPointerOver)
-                    {
-                        SetExclusivePseudoClass(pcSecondaryPointerOver);
-                    }
-                    else
-                    {
-                        // Calling without a parameter is treated as ':normal' and will clear all other
-                        // PseudoClasses returning to the default state
-                        SetExclusivePseudoClass();
-                    }
-                }
-            }
-
-            // Local function to enable the specified PseudoClass and disable all others
-            // This more closely matches the VisualStateManager of WinUI where the default style originated
-            void SetExclusivePseudoClass(string pseudoClass = "")
-            {
-                PseudoClasses.Set(pcDisabled, pseudoClass == pcDisabled);
-
-                PseudoClasses.Set(pcCheckedFlyoutOpen, pseudoClass == pcCheckedFlyoutOpen);
-                PseudoClasses.Set(pcFlyoutOpen,        pseudoClass == pcFlyoutOpen);
-
-                PseudoClasses.Set(pcCheckedTouchPressed,         pseudoClass == pcCheckedTouchPressed);
-                PseudoClasses.Set(pcChecked,                     pseudoClass == pcChecked);
-                PseudoClasses.Set(pcCheckedPrimaryPressed,       pseudoClass == pcCheckedPrimaryPressed);
-                PseudoClasses.Set(pcCheckedPrimaryPointerOver,   pseudoClass == pcCheckedPrimaryPointerOver);
-                PseudoClasses.Set(pcCheckedSecondaryPressed,     pseudoClass == pcCheckedSecondaryPressed);
-                PseudoClasses.Set(pcCheckedSecondaryPointerOver, pseudoClass == pcCheckedSecondaryPointerOver);
-
-                PseudoClasses.Set(pcTouchPressed,         pseudoClass == pcTouchPressed);
-                PseudoClasses.Set(pcPrimaryPressed,       pseudoClass == pcPrimaryPressed);
-                PseudoClasses.Set(pcPrimaryPointerOver,   pseudoClass == pcPrimaryPointerOver);
-                PseudoClasses.Set(pcSecondaryPressed,     pseudoClass == pcSecondaryPressed);
-                PseudoClasses.Set(pcSecondaryPointerOver, pseudoClass == pcSecondaryPointerOver);
-            }
+            PseudoClasses.Set(pcFlyoutOpen, _isFlyoutOpen);
+            PseudoClasses.Set(pcChecked, GetValue(ToggleSplitButton.IsCheckedProperty));
         }
 
         /// <summary>
@@ -387,29 +198,14 @@ namespace Avalonia.Controls
         /// </summary>
         private void UnregisterEvents()
         {
-            _buttonPropertyChangedDisposable?.Dispose();
-            _buttonPropertyChangedDisposable = null;
-
             if (_primaryButton != null)
             {
                 _primaryButton.Click -= PrimaryButton_Click;
-
-                _primaryButton.PointerEnter       -= Button_PointerEvent;
-                _primaryButton.PointerLeave       -= Button_PointerEvent;
-                _primaryButton.PointerPressed     -= Button_PointerEvent;
-                _primaryButton.PointerReleased    -= Button_PointerEvent;
-                _primaryButton.PointerCaptureLost -= Button_PointerCaptureLost;
             }
 
             if (_secondaryButton != null)
             {
                 _secondaryButton.Click -= SecondaryButton_Click;
-
-                _secondaryButton.PointerEnter       -= Button_PointerEvent;
-                _secondaryButton.PointerLeave       -= Button_PointerEvent;
-                _secondaryButton.PointerPressed     -= Button_PointerEvent;
-                _secondaryButton.PointerReleased    -= Button_PointerEvent;
-                _secondaryButton.PointerCaptureLost -= Button_PointerCaptureLost;
             }
         }
 
@@ -426,54 +222,18 @@ namespace Avalonia.Controls
             _primaryButton   = e.NameScope.Find<Button>("PART_PrimaryButton");
             _secondaryButton = e.NameScope.Find<Button>("PART_SecondaryButton");
 
-            _buttonPropertyChangedDisposable = new CompositeDisposable();
-
             if (_primaryButton != null)
             {
                 _primaryButton.Click += PrimaryButton_Click;
-
-                _buttonPropertyChangedDisposable.Add(_primaryButton.GetPropertyChangedObservable(Button.IsPressedProperty).Subscribe(Button_VisualPropertyChanged));
-                _buttonPropertyChangedDisposable.Add(_primaryButton.GetPropertyChangedObservable(Button.IsPointerOverProperty).Subscribe(Button_VisualPropertyChanged));
-
-                // Register for pointer events to keep track of the last used pointer type and update visual states
-                _primaryButton.PointerEnter       += Button_PointerEvent;
-                _primaryButton.PointerLeave       += Button_PointerEvent;
-                _primaryButton.PointerPressed     += Button_PointerEvent;
-                _primaryButton.PointerReleased    += Button_PointerEvent;
-                _primaryButton.PointerCaptureLost += Button_PointerCaptureLost;
             }
 
             if (_secondaryButton != null)
             {
                 _secondaryButton.Click += SecondaryButton_Click;
-
-                _buttonPropertyChangedDisposable.Add(_secondaryButton.GetPropertyChangedObservable(Button.IsPressedProperty).Subscribe(Button_VisualPropertyChanged));
-                _buttonPropertyChangedDisposable.Add(_secondaryButton.GetPropertyChangedObservable(Button.IsPointerOverProperty).Subscribe(Button_VisualPropertyChanged));
-
-                // Register for pointer events to keep track of the last used pointer type and update visual states
-                _secondaryButton.PointerEnter       += Button_PointerEvent;
-                _secondaryButton.PointerLeave       += Button_PointerEvent;
-                _secondaryButton.PointerPressed     += Button_PointerEvent;
-                _secondaryButton.PointerReleased    += Button_PointerEvent;
-                _secondaryButton.PointerCaptureLost += Button_PointerCaptureLost;
             }
 
             RegisterFlyoutEvents(Flyout);
             UpdatePseudoClasses();
-
-            _hasLoaded = true;
-        }
-
-        /// <inheritdoc/>
-        protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
-        {
-            base.OnAttachedToVisualTree(e);
-        }
-
-        /// <inheritdoc/>
-        protected override void OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs e)
-        {
-            base.OnDetachedFromVisualTree(e);
         }
 
         /// <inheritdoc/>
@@ -566,7 +326,6 @@ namespace Avalonia.Controls
 
             if (key == Key.Space || key == Key.Enter) // Key.GamepadA is not currently supported
             {
-                _isKeyDown = true;
                 UpdatePseudoClasses();
             }
 
@@ -580,7 +339,6 @@ namespace Avalonia.Controls
 
             if (key == Key.Space || key == Key.Enter) // Key.GamepadA is not currently supported
             {
-                _isKeyDown = false;
                 UpdatePseudoClasses();
 
                 // Consider this a click on the primary button
@@ -623,7 +381,7 @@ namespace Avalonia.Controls
             // Note: It is not currently required to check enabled status; however, this is a failsafe
             if (IsEffectivelyEnabled)
             {
-                var eventArgs = new RoutedEventArgs(ClickEvent);
+                var eventArgs = new RoutedEventArgs(Button.ClickEvent);
                 RaiseEvent(eventArgs);
 
                 if (!eventArgs.Handled && Command?.CanExecute(CommandParameter) == true)
@@ -667,43 +425,6 @@ namespace Avalonia.Controls
             OnClickSecondary(e);
         }
 
-        /// <summary>
-        /// Event handler for when pointer events occur in the primary or secondary buttons.
-        /// </summary>
-        private void Button_PointerEvent(object sender, PointerEventArgs e)
-        {
-            // Warning: Code must match with Button_PointerCaptureLost
-            if (_lastPointerType != e.Pointer.Type)
-            {
-                _lastPointerType = e.Pointer.Type;
-                UpdatePseudoClasses();
-            }
-        }
-
-        /// <summary>
-        /// Event handler for when the pointer capture is lost in the primary or secondary buttons.
-        /// </summary>
-        /// <remarks>
-        /// In upstream WinUI this is not a separate event handler. However, Avalonia has different args.
-        /// </remarks>
-        private void Button_PointerCaptureLost(object sender, PointerCaptureLostEventArgs e)
-        {
-            // Warning: Code must match with Button_PointerEvent
-            if (_lastPointerType != e.Pointer.Type)
-            {
-                _lastPointerType = e.Pointer.Type;
-                UpdatePseudoClasses();
-            }
-        }
-
-        /// <summary>
-        /// Called when a primary or secondary button property changes that affects the visual states.
-        /// </summary>
-        private void Button_VisualPropertyChanged(AvaloniaPropertyChangedEventArgs e)
-        {
-            UpdatePseudoClasses();
-        }
-
         /// <summary>
         /// Called when the <see cref="FlyoutBase.Placement"/> property changes.
         /// </summary>
diff --git a/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs b/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
index bd19fa213e..c926250105 100644
--- a/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
@@ -1,4 +1,6 @@
 using System;
+
+using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Primitives;
 using Avalonia.Interactivity;
 using Avalonia.Styling;
@@ -10,6 +12,7 @@ namespace Avalonia.Controls
     /// The primary part behaves like a <see cref="ToggleButton"/> with two states and
     /// the secondary part opens a flyout.
     /// </summary>
+    [PseudoClasses(pcChecked)]
     public class ToggleSplitButton : SplitButton, IStyleable
     {
         /// <summary>
@@ -101,7 +104,8 @@ namespace Avalonia.Controls
         /// </summary>
         protected virtual void OnIsCheckedChanged()
         {
-            if (_hasLoaded)
+            // IsLoaded check
+            if (Parent is not null)
             {
                 var eventArgs = new RoutedEventArgs(IsCheckedChangedEvent);
                 RaiseEvent(eventArgs);
diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index b05e1341bb..d0ddcdb2aa 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -3,14 +3,26 @@
         x:CompileBindings="True">
 
   <Design.PreviewWith>
-    <Border Padding="20">
-      <SplitButton />
+    <Border Padding="60">
+      <StackPanel>
+        <SplitButton Content="Hello World">
+          <SplitButton.Flyout>
+            <Flyout>Hello</Flyout>
+          </SplitButton.Flyout>
+        </SplitButton>
+        <ToggleSplitButton Content="Hello World">
+          <ToggleSplitButton.Flyout>
+            <Flyout>Hello</Flyout>
+          </ToggleSplitButton.Flyout>
+        </ToggleSplitButton>
+      </StackPanel>
     </Border>
   </Design.PreviewWith>
 
   <Styles.Resources>
     <x:Double x:Key="SplitButtonPrimaryButtonSize">32</x:Double>
-    <GridLength x:Key="SplitButtonSecondaryButtonSize">32</GridLength>
+    <x:Double x:Key="SplitButtonSecondaryButtonSize">32</x:Double>
+    <StreamGeometry x:Key="SplitButtonSecondaryButtonIconGeometry">M1939 486L2029 576L1024 1581L19 576L109 486L1024 1401L1939 486Z</StreamGeometry>
   </Styles.Resources>
 
   <Style Selector="SplitButton">
@@ -20,380 +32,174 @@
     <Setter Property="BorderThickness" Value="{DynamicResource SplitButtonBorderThemeThickness}" />
     <Setter Property="HorizontalAlignment" Value="Left" />
     <Setter Property="VerticalAlignment" Value="Center" />
-    <!--<Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}" />
-    <Setter Property="FontWeight" Value="Normal" />
-    <Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}" />
-    <Setter Property="UseSystemFocusVisuals" Value="True" />
+    <!--<Setter Property="UseSystemFocusVisuals" Value="True" />
     <Setter Property="FocusVisualMargin" Value="-3" />-->
     <Setter Property="KeyboardNavigation.IsTabStop" Value="True" />
+    <Setter Property="Focusable" Value="True" />
     <Setter Property="Padding" Value="{DynamicResource ButtonPadding}" />
     <Setter Property="CornerRadius" Value="{DynamicResource ControlCornerRadius}" />
     <Setter Property="Template">
       <Setter.Value>
         <ControlTemplate>
-          <!-- A Border was added here since Avalonia does not support Background/Border/CornerRadius on Grid directly
-               This also allowed removing the extra background border and integrating it here. -->
-          <Border x:Name="RootBorder"
-                  Background="Transparent"
-                  BorderBrush="{TemplateBinding BorderBrush}"
-                  BorderThickness="{TemplateBinding BorderThickness}"
-                  CornerRadius="{TemplateBinding CornerRadius}">
-            <!-- In WinUI, a separate child style for the inner buttons is provided here.
-                 For avalonia that style is simplified and pulled out separately below.
-                 A style is needed to override any button default background/foreground/border colors, etc. -->
-            <Grid>
-              
-              <Grid.ColumnDefinitions>
-                <ColumnDefinition Width="*"
-                                  MinWidth="{StaticResource SplitButtonPrimaryButtonSize}" />
-                <ColumnDefinition Width="1" />
-                <ColumnDefinition Width="{StaticResource SplitButtonSecondaryButtonSize}" />
-              </Grid.ColumnDefinitions>
-
-              <!-- Changed from Grid to Border since Avalonia does not support Background/CornerRadius on Grid directly -->
-              <Border x:Name="PrimaryBackgroundBorder"
-                      Background="{TemplateBinding Background}"
-                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource LeftCornerRadiusFilterConverter}}" />
-
-              <Border x:Name="SecondaryBackgroundBorder"
-                      Background="{TemplateBinding Background}"
-                      Grid.Column="2"
-                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource RightCornerRadiusFilterConverter}}" />
-
-              <Button x:Name="PART_PrimaryButton"
-                      Grid.Column="0"
-                      Foreground="{TemplateBinding Foreground}"
-                      Background="{TemplateBinding Background}"
-                      BorderThickness="{TemplateBinding BorderThickness}"
-                      BorderBrush="Transparent"
-                      Content="{TemplateBinding Content}"
-                      ContentTemplate="{TemplateBinding ContentTemplate}"
-                      Command="{TemplateBinding Command}"
-                      CommandParameter="{TemplateBinding CommandParameter}"
-                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource LeftCornerRadiusFilterConverter}}"
-                      FontFamily="{TemplateBinding FontFamily}"
-                      FontSize="{TemplateBinding FontSize}"
-                      FontWeight="{TemplateBinding FontWeight}"
-                      HorizontalAlignment="Stretch"
-                      VerticalAlignment="Stretch"
-                      HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
-                      VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
-                      Padding="{TemplateBinding Padding}"
-                      KeyboardNavigation.IsTabStop="False" />
-
-              <Button x:Name="PART_SecondaryButton"
-                      Grid.Column="2"
-                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource RightCornerRadiusFilterConverter}}"
-                      Foreground="{TemplateBinding Foreground}"
-                      Background="{TemplateBinding Background}"
-                      BorderThickness="{TemplateBinding BorderThickness}"
-                      BorderBrush="Transparent"
-                      HorizontalContentAlignment="Right"
-                      VerticalContentAlignment="Center"
-                      HorizontalAlignment="Stretch"
-                      VerticalAlignment="Stretch"
-                      KeyboardNavigation.IsTabStop="False"
-                      Padding="0,0,10,0">
-                <Button.Content>
-                  <!-- TextBlock converted to a Path and placed within Viewbox -->
-                  <Viewbox UseLayoutRounding="False"
-                           IsHitTestVisible="False"
-                           Height="12"
-                           Width="12">
-                    <Path x:Name="DropDownGlyphPath"
-                          VerticalAlignment="Center"
-                          HorizontalAlignment="Right"
-                          Fill="{TemplateBinding Foreground}"
-                          Data="M1939 486L2029 576L1024 1581L19 576L109 486L1024 1401L1939 486Z"
-                          Stretch="Uniform" />
-                  </Viewbox>
-                </Button.Content>
-              </Button>
-            </Grid>
-          </Border>
+          <Grid>
+            <Grid.ColumnDefinitions>
+              <ColumnDefinition Width="*" />
+              <ColumnDefinition Width="Auto" />
+            </Grid.ColumnDefinitions>
+
+            <Button x:Name="PART_PrimaryButton"
+                    Grid.Column="0"
+                    MinWidth="{DynamicResource SplitButtonPrimaryButtonSize}"
+                    Foreground="{TemplateBinding Foreground}"
+                    Background="{TemplateBinding Background}"
+                    BorderThickness="{TemplateBinding BorderThickness}"
+                    BorderBrush="{TemplateBinding BorderBrush}"
+                    Content="{TemplateBinding Content}"
+                    ContentTemplate="{TemplateBinding ContentTemplate}"
+                    Command="{TemplateBinding Command}"
+                    CommandParameter="{TemplateBinding CommandParameter}"
+                    FontFamily="{TemplateBinding FontFamily}"
+                    FontSize="{TemplateBinding FontSize}"
+                    FontWeight="{TemplateBinding FontWeight}"
+                    HorizontalAlignment="Stretch"
+                    VerticalAlignment="Stretch"
+                    HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                    VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
+                    Padding="{TemplateBinding Padding}"
+                    Focusable="False"
+                    KeyboardNavigation.IsTabStop="False" />
+
+            <Button x:Name="PART_SecondaryButton"
+                    Grid.Column="1"
+                    MinWidth="{DynamicResource SplitButtonSecondaryButtonSize}"
+                    BorderBrush="{TemplateBinding BorderBrush}"
+                    Foreground="{TemplateBinding Foreground}"
+                    Background="{TemplateBinding Background}"
+                    BorderThickness="{TemplateBinding BorderThickness}"
+                    HorizontalContentAlignment="Right"
+                    VerticalContentAlignment="Center"
+                    HorizontalAlignment="Stretch"
+                    VerticalAlignment="Stretch"
+                    Focusable="False"
+                    KeyboardNavigation.IsTabStop="False" />
+          </Grid>
         </ControlTemplate>
       </Setter.Value>
     </Setter>
   </Style>
 
-  <!-- Normal State (not a PseudoClass) -->
-  <!-- The 'Button' style here was moved out of the main style above.
-       In WinUI there is a child, customized style shared for both primary and secondary buttons.
-       In Avalonia, we can use selectors to make a 'normal' style apply only to those buttons but
-       pull it out separately from the full style above. -->
-  <Style Selector="SplitButton /template/ Button">
-    <!-- Applies to both Primary/Secondary buttons -->
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForeground}" />
-    <Setter Property="BorderBrush" Value="Transparent" />
-    <Setter Property="BorderThickness" Value="{DynamicResource SplitButtonBorderThemeThickness}" />
-    <Setter Property="Template">
-      <ControlTemplate>
-        <!-- Switched from Grid to Border to optimize and support Foreground/Background properties -->
-        <!-- It is important for the background to be clear and no CornerRadius set. -->
-        <Border Background="Transparent">
-          <ContentPresenter x:Name="ContentPresenter"
-                            BorderBrush="{TemplateBinding BorderBrush}"
-                            BorderThickness="{TemplateBinding BorderThickness}"
-                            Content="{TemplateBinding Content}"
-                            ContentTemplate="{TemplateBinding ContentTemplate}"
-                            Padding="{TemplateBinding Padding}"
-                            HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
-                            VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" />
-        </Border>
-      </ControlTemplate>
+  <!-- Default overridable styles -->
+  <Style Selector="SplitButton /template/ Button#PART_PrimaryButton">
+    <Setter Property="CornerRadius" Value="{TemplateBinding CornerRadius, Converter={StaticResource LeftCornerRadiusFilterConverter}}" />
+  </Style>
+  <Style Selector="SplitButton /template/ Button#PART_SecondaryButton">
+    <Setter Property="CornerRadius" Value="{TemplateBinding CornerRadius, Converter={StaticResource RightCornerRadiusFilterConverter}}" />
+    <Setter Property="Padding" Value="9,0" />
+    <Setter Property="Content">
+      <Template>
+        <PathIcon Height="12"
+                  Width="12"
+                  Data="{StaticResource SplitButtonSecondaryButtonIconGeometry}" />
+      </Template>
     </Setter>
   </Style>
 
-  <!-- Disabled State -->
-  <Style Selector="SplitButton:disabled /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushDisabled}" />
-  </Style>
-  <Style Selector="SplitButton:disabled /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundDisabled}" />
+  <!-- Primary and Secondary buttons PointerOver State -->
+  <Style Selector="SplitButton /template/ Button#PART_PrimaryButton:pointerover /template/ ContentPresenter,
+         SplitButton /template/ Button#PART_SecondaryButton:pointerover /template/ ContentPresenter">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:disabled /template/ Button">
-    <!-- Applies to both Primary/Secondary buttons -->
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundDisabled}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundDisabled}" />
+  <Style Selector="SplitButton /template/ Button#PART_SecondaryButton:pointerover PathIcon">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
   </Style>
 
-  <!-- FlyoutOpen State -->
-  <Style Selector="SplitButton:flyout-open /template/ Border#PrimaryBackgroundBorder">
+  <!-- Primary and Secondary buttons Pressed State -->
+  <Style Selector="SplitButton /template/ Button#PART_PrimaryButton:pressed /template/ ContentPresenter,
+         SplitButton /template/ Button#PART_SecondaryButton:pressed /template/ ContentPresenter">
     <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:flyout-open /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:flyout-open /template/ Border#RootBorder">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:flyout-open /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:flyout-open /template/ Button#PART_SecondaryButton">
+  <Style Selector="SplitButton /template/ Button#PART_SecondaryButton:pressed PathIcon">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
 
-  <!-- TouchPressed State -->
-  <Style Selector="SplitButton:touch-pressed /template/ Border#PrimaryBackgroundBorder">
+  <!-- Primary and Secondary buttons Flyout Open State -->
+  <Style Selector="SplitButton:flyout-open /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:flyout-open /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
     <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:touch-pressed /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:touch-pressed /template/ Border#RootBorder">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:touch-pressed /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:touch-pressed /template/ Button#PART_SecondaryButton">
+  <Style Selector="SplitButton:flyout-open /template/ Button#PART_SecondaryButton PathIcon">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
 
-  <!-- PrimaryPointerOver State -->
-  <Style Selector="SplitButton:primary-pointerover /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
-  </Style>
-  <Style Selector="SplitButton:primary-pointerover /template/ Button#PART_PrimaryButton">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
-  </Style>
-  <Style Selector="SplitButton:primary-pointerover /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
-  </Style>
-
-  <!-- PrimaryPressed State -->
-  <Style Selector="SplitButton:primary-pressed /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:primary-pressed /template/ Button#PART_PrimaryButton">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:primary-pressed /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
-  </Style>
-
-  <!-- SecondaryPointerOver State -->
-  <Style Selector="SplitButton:secondary-pointerover /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
-  </Style>
-  <Style Selector="SplitButton:secondary-pointerover /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
-  </Style>
-  <Style Selector="SplitButton:secondary-pointerover /template/ Button#PART_SecondaryButton">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
-  </Style>
-
-  <!-- SecondaryPressed State -->
-  <Style Selector="SplitButton:secondary-pressed /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
-  </Style>
-  <Style Selector="SplitButton:secondary-pressed /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+  <!-- Disabled State -->
+  <Style Selector="SplitButton:disabled /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:disabled /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundDisabled}" />
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushDisabled}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundDisabled}" />
   </Style>
-  <Style Selector="SplitButton:secondary-pressed /template/ Button#PART_SecondaryButton">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  <Style Selector="SplitButton:disabled /template/ Button#PART_SecondaryButton PathIcon">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundDisabled}" />
   </Style>
 
   <!-- Checked State -->
-  <Style Selector="SplitButton:checked /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked /template/ Border#SecondaryBackgroundBorder">
+  <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:checked /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
     <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked /template/ Border#RootBorder">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton">
+  <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton PathIcon">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
 
-  <!-- CheckedFlyoutOpen State -->
-  <Style Selector="SplitButton:checked-flyout-open /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Button#PART_SecondaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
-
-  <!-- CheckedTouchPressed State -->
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Button#PART_SecondaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
-
-  <!-- CheckedPrimaryPointerOver State -->
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#PrimaryBackgroundBorder">
+  <!-- Checked PointerOver State -->
+  <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton:pointerover /template/ ContentPresenter,
+         SplitButton:checked /template/ Button#PART_SecondaryButton:pointerover /template/ ContentPresenter">
     <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#PART_PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#PART_SecondaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton:pointerover PathIcon">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
   </Style>
 
-  <!-- CheckedPrimaryPressed State -->
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#PrimaryBackgroundBorder">
+  <!-- Checked Pressed State -->
+  <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton:pressed /template/ ContentPresenter,
+         SplitButton:checked /template/ Button#PART_SecondaryButton:pressed /template/ ContentPresenter">
     <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Button#PART_PrimaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Button#PART_SecondaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
-
-  <!-- CheckedSecondaryPointerOver State -->
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Button#PART_SecondaryButton">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
+  <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton:pressed PathIcon">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
 
-  <!-- CheckedSecondaryPressed State -->
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#SecondaryBackgroundBorder">
+  <!-- Checked Flyout Open State -->
+  <Style Selector="SplitButton:checked:flyout-open /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:checked:flyout-open /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
     <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Button#PART_SecondaryButton">
     <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  <Style Selector="SplitButton:checked:flyout-open /template/ Button#PART_SecondaryButton PathIcon">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
 
-  <!-- SecondaryButtonPlacement States -->
-  <!-- Note: Setting Grid attached properties doesn't work here for some unknown reason.
-       They simply are never changed. In addition, touch-device changes of secondary button
-       size are currently disabled in code-behind. -->
-  <Style Selector="SplitButton:secondary-button-right /template/ Button#PART_SecondaryButton">
-    <Setter Property="(Grid.Column)" Value="2" />
-    <Setter Property="(Grid.ColumnSpan)" Value="1" />
+  <!-- Disabled Checked State -->
+  <Style Selector="SplitButton:checked:disabled /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:checked:disabled /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedDisabled}" />
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedDisabled}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedDisabled}" />
   </Style>
-  <Style Selector="SplitButton:secondary-button-span /template/ Button#PART_SecondaryButton">
-    <Setter Property="(Grid.Column)" Value="0" />
-    <Setter Property="(Grid.ColumnSpan)" Value="3" />
+  <Style Selector="SplitButton:checked:disabled /template/ Button#PART_SecondaryButton PathIcon">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedDisabled}" />
   </Style>
-
 </Styles>

From ee36313c3ecbbec7cf73e981c5cbab10f88bdf78 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Thu, 27 Jan 2022 11:27:24 -0500
Subject: [PATCH 31/48] Revert "Move more Button property changed handling into
 OnPropertyChanged override"

This reverts commit 853d4140a301f09cfa4bc4727c086459de903169.
---
 src/Avalonia.Controls/Button.cs               | 142 +++++++++++-------
 .../SplitButton/SplitButton.cs                |   4 +-
 2 files changed, 89 insertions(+), 57 deletions(-)

diff --git a/src/Avalonia.Controls/Button.cs b/src/Avalonia.Controls/Button.cs
index 3735e6c010..770eb63266 100644
--- a/src/Avalonia.Controls/Button.cs
+++ b/src/Avalonia.Controls/Button.cs
@@ -59,13 +59,13 @@ namespace Avalonia.Controls
             AvaloniaProperty.Register<Button, object>(nameof(CommandParameter));
 
         /// <summary>
-        /// Defines the <see cref="IsDefault"/> property.
+        /// Defines the <see cref="IsDefaultProperty"/> property.
         /// </summary>
         public static readonly StyledProperty<bool> IsDefaultProperty =
             AvaloniaProperty.Register<Button, bool>(nameof(IsDefault));
 
         /// <summary>
-        /// Defines the <see cref="IsCancel"/> property.
+        /// Defines the <see cref="IsCancelProperty"/> property.
         /// </summary>
         public static readonly StyledProperty<bool> IsCancelProperty =
             AvaloniaProperty.Register<Button, bool>(nameof(IsCancel));
@@ -98,6 +98,10 @@ namespace Avalonia.Controls
         static Button()
         {
             FocusableProperty.OverrideDefaultValue(typeof(Button), true);
+            CommandProperty.Changed.Subscribe(CommandChanged);
+            CommandParameterProperty.Changed.Subscribe(CommandParameterChanged);
+            IsDefaultProperty.Changed.Subscribe(IsDefaultChanged);
+            IsCancelProperty.Changed.Subscribe(IsCancelChanged);
             AccessKeyHandler.AccessKeyPressedEvent.AddClassHandler<Button>((lbl, args) => lbl.OnAccessKey(args));
         }
 
@@ -386,88 +390,116 @@ namespace Avalonia.Controls
         {
             base.OnPropertyChanged(change);
 
-            if (change.Property == CommandProperty)
+            if (change.Property == IsPressedProperty)
             {
-                if (((ILogical)this).IsAttachedToLogicalTree)
-                {
-                    if (change.OldValue.GetValueOrDefault() is ICommand oldCommand)
-                    {
-                        oldCommand.CanExecuteChanged -= CanExecuteChanged;
-                    }
-
-                    if (change.NewValue.GetValueOrDefault() is ICommand newCommand)
-                    {
-                        newCommand.CanExecuteChanged += CanExecuteChanged;
-                    }
-                }
-
-                CanExecuteChanged(this, EventArgs.Empty);
+                UpdatePseudoClasses(change.NewValue.GetValueOrDefault<bool>());
             }
-            else if (change.Property == CommandParameterProperty)
+            else if (change.Property == FlyoutProperty)
             {
-                CanExecuteChanged(this, EventArgs.Empty);
+                // If flyout is changed while one is already open, make sure we 
+                // close the old one first
+                if (change.OldValue.GetValueOrDefault() is FlyoutBase oldFlyout &&
+                    oldFlyout.IsOpen)
+                {
+                    oldFlyout.Hide();
+                }
             }
-            else if (change.Property == IsCancelProperty)
-            {
-                var isCancel = change.NewValue.GetValueOrDefault<bool>();
+        }
 
-                if (VisualRoot is IInputElement inputRoot)
+        /// <inheritdoc/>
+        protected override void UpdateDataValidation<T>(AvaloniaProperty<T> property, BindingValue<T> value)
+        {
+            base.UpdateDataValidation(property, value);
+            if (property == CommandProperty)
+            {
+                if (value.Type == BindingValueType.BindingError)
                 {
-                    if (isCancel)
-                    {
-                        ListenForCancel(inputRoot);
-                    }
-                    else
+                    if (_commandCanExecute)
                     {
-                        StopListeningForCancel(inputRoot);
+                        _commandCanExecute = false;
+                        UpdateIsEffectivelyEnabled();
                     }
                 }
             }
-            else if (change.Property == IsDefaultProperty)
-            {
-                var isDefault = change.NewValue.GetValueOrDefault<bool>();
+        }
 
-                if (VisualRoot is IInputElement inputRoot)
+        /// <summary>
+        /// Called when the <see cref="Command"/> property changes.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        private static void CommandChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            if (e.Sender is Button button)
+            {
+                if (((ILogical)button).IsAttachedToLogicalTree)
                 {
-                    if (isDefault)
+                    if (e.OldValue is ICommand oldCommand)
                     {
-                        ListenForDefault(inputRoot);
+                        oldCommand.CanExecuteChanged -= button.CanExecuteChanged;
                     }
-                    else
+
+                    if (e.NewValue is ICommand newCommand)
                     {
-                        StopListeningForDefault(inputRoot);
+                        newCommand.CanExecuteChanged += button.CanExecuteChanged;
                     }
                 }
+
+                button.CanExecuteChanged(button, EventArgs.Empty);
             }
-            else if (change.Property == IsPressedProperty)
+        }
+
+        /// <summary>
+        /// Called when the <see cref="CommandParameter"/> property changes.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        private static void CommandParameterChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            if (e.Sender is Button button)
             {
-                UpdatePseudoClasses(change.NewValue.GetValueOrDefault<bool>());
+                button.CanExecuteChanged(button, EventArgs.Empty);
             }
-            else if (change.Property == FlyoutProperty)
+        }
+
+        /// <summary>
+        /// Called when the <see cref="IsDefault"/> property changes.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        private static void IsDefaultChanged(AvaloniaPropertyChangedEventArgs e)
+        {
+            var button = e.Sender as Button;
+            var isDefault = (bool)e.NewValue;
+
+            if (button?.VisualRoot is IInputElement inputRoot)
             {
-                // If flyout is changed while one is already open, make sure we 
-                // close the old one first
-                if (change.OldValue.GetValueOrDefault() is FlyoutBase oldFlyout &&
-                    oldFlyout.IsOpen)
+                if (isDefault)
                 {
-                    oldFlyout.Hide();
+                    button.ListenForDefault(inputRoot);
+                }
+                else
+                {
+                    button.StopListeningForDefault(inputRoot);
                 }
             }
         }
 
-        /// <inheritdoc/>
-        protected override void UpdateDataValidation<T>(AvaloniaProperty<T> property, BindingValue<T> value)
+        /// <summary>
+        /// Called when the <see cref="IsCancel"/> property changes.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        private static void IsCancelChanged(AvaloniaPropertyChangedEventArgs e)
         {
-            base.UpdateDataValidation(property, value);
-            if (property == CommandProperty)
+            var button = e.Sender as Button;
+            var isCancel = (bool)e.NewValue;
+
+            if (button?.VisualRoot is IInputElement inputRoot)
             {
-                if (value.Type == BindingValueType.BindingError)
+                if (isCancel)
                 {
-                    if (_commandCanExecute)
-                    {
-                        _commandCanExecute = false;
-                        UpdateIsEffectivelyEnabled();
-                    }
+                    button.ListenForCancel(inputRoot);
+                }
+                else
+                {
+                    button.StopListeningForCancel(inputRoot);
                 }
             }
         }
diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index 13d3572975..6391812bed 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -271,12 +271,12 @@ namespace Avalonia.Controls
                 if (_isAttachedToLogicalTree)
                 {
                     // Must unregister events here while a reference to the old command still exists
-                    if (e.OldValue.GetValueOrDefault() is ICommand oldCommand)
+                    if (e.OldValue is ICommand oldCommand)
                     {
                         oldCommand.CanExecuteChanged -= CanExecuteChanged;
                     }
 
-                    if (e.NewValue.GetValueOrDefault() is ICommand newCommand)
+                    if (e.NewValue is ICommand newCommand)
                     {
                         newCommand.CanExecuteChanged += CanExecuteChanged;
                     }

From 83720e9218047752d91105e1478bd3c024b28a6e Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Thu, 27 Jan 2022 11:27:54 -0500
Subject: [PATCH 32/48] Revert "Minor refactoring to Button noticed when adding
 SplitButton"

This reverts commit c0bb7efa12d9cfce1c1ae7532057d4e40062a11c.
---
 src/Avalonia.Controls/Button.cs | 61 ++++++++++++---------------------
 1 file changed, 22 insertions(+), 39 deletions(-)

diff --git a/src/Avalonia.Controls/Button.cs b/src/Avalonia.Controls/Button.cs
index 770eb63266..8537c9acbc 100644
--- a/src/Avalonia.Controls/Button.cs
+++ b/src/Avalonia.Controls/Button.cs
@@ -76,9 +76,6 @@ namespace Avalonia.Controls
         public static readonly RoutedEvent<RoutedEventArgs> ClickEvent =
             RoutedEvent.Register<Button, RoutedEventArgs>(nameof(Click), RoutingStrategies.Bubble);
 
-        /// <summary>
-        /// Defines the <see cref="IsPressed"/> property.
-        /// </summary>
         public static readonly StyledProperty<bool> IsPressedProperty =
             AvaloniaProperty.Register<Button, bool>(nameof(IsPressed));
 
@@ -105,9 +102,6 @@ namespace Avalonia.Controls
             AccessKeyHandler.AccessKeyPressedEvent.AddClassHandler<Button>((lbl, args) => lbl.OnAccessKey(args));
         }
 
-        /// <summary>
-        /// Initializes a new instance of the <see cref="Button"/> class.
-        /// </summary>
         public Button()
         {
             UpdatePseudoClasses(IsPressed);
@@ -118,8 +112,8 @@ namespace Avalonia.Controls
         /// </summary>
         public event EventHandler<RoutedEventArgs> Click
         {
-            add => AddHandler(ClickEvent, value);
-            remove => RemoveHandler(ClickEvent, value);
+            add { AddHandler(ClickEvent, value); }
+            remove { RemoveHandler(ClickEvent, value); }
         }
 
         /// <summary>
@@ -127,8 +121,8 @@ namespace Avalonia.Controls
         /// </summary>
         public ClickMode ClickMode
         {
-            get => GetValue(ClickModeProperty);
-            set => SetValue(ClickModeProperty, value);
+            get { return GetValue(ClickModeProperty); }
+            set { SetValue(ClickModeProperty, value); }
         }
 
         /// <summary>
@@ -136,8 +130,8 @@ namespace Avalonia.Controls
         /// </summary>
         public ICommand Command
         {
-            get => _command;
-            set => SetAndRaise(CommandProperty, ref _command, value);
+            get { return _command; }
+            set { SetAndRaise(CommandProperty, ref _command, value); }
         }
 
         /// <summary>
@@ -145,8 +139,8 @@ namespace Avalonia.Controls
         /// </summary>
         public KeyGesture HotKey
         {
-            get => GetValue(HotKeyProperty);
-            set => SetValue(HotKeyProperty, value);
+            get { return GetValue(HotKeyProperty); }
+            set { SetValue(HotKeyProperty, value); }
         }
 
         /// <summary>
@@ -154,8 +148,8 @@ namespace Avalonia.Controls
         /// </summary>
         public object CommandParameter
         {
-            get => GetValue(CommandParameterProperty);
-            set => SetValue(CommandParameterProperty, value);
+            get { return GetValue(CommandParameterProperty); }
+            set { SetValue(CommandParameterProperty, value); }
         }
 
         /// <summary>
@@ -164,8 +158,8 @@ namespace Avalonia.Controls
         /// </summary>
         public bool IsDefault
         {
-            get => GetValue(IsDefaultProperty);
-            set => SetValue(IsDefaultProperty, value);
+            get { return GetValue(IsDefaultProperty); }
+            set { SetValue(IsDefaultProperty, value); }
         }
 
         /// <summary>
@@ -174,21 +168,18 @@ namespace Avalonia.Controls
         /// </summary>
         public bool IsCancel
         {
-            get => GetValue(IsCancelProperty);
-            set => SetValue(IsCancelProperty, value);
+            get { return GetValue(IsCancelProperty); }
+            set { SetValue(IsCancelProperty, value); }
         }
 
-        /// <summary>
-        /// Gets or sets a value indicating whether the button is currently pressed.
-        /// </summary>
         public bool IsPressed
         {
-            get => GetValue(IsPressedProperty);
-            private set => SetValue(IsPressedProperty, value);
+            get { return GetValue(IsPressedProperty); }
+            private set { SetValue(IsPressedProperty, value); }
         }
 
         /// <summary>
-        /// Gets or sets the Flyout that should be shown with this button.
+        /// Gets or sets the Flyout that should be shown with this button
         /// </summary>
         public FlyoutBase Flyout
         {
@@ -196,8 +187,7 @@ namespace Avalonia.Controls
             set => SetValue(FlyoutProperty, value);
         }
 
-        /// <inheritdoc/>
-        protected override bool IsEnabledCore => base.IsEnabledCore && _commandCanExecute;
+        protected override bool IsEnabledCore => base.IsEnabledCore && _commandCanExecute; 
 
         /// <inheritdoc/>
         protected override void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
@@ -234,7 +224,6 @@ namespace Avalonia.Controls
             }
         }
 
-        /// <inheritdoc/>
         protected override void OnAttachedToLogicalTree(LogicalTreeAttachmentEventArgs e)
         {
             if (_hotkey != null) // Control attached again, set Hotkey to create a hotkey manager for this control
@@ -251,7 +240,6 @@ namespace Avalonia.Controls
             }
         }
 
-        /// <inheritdoc/>
         protected override void OnDetachedFromLogicalTree(LogicalTreeAttachmentEventArgs e)
         {
             // This will cause the hotkey manager to dispose the observer and the reference to this control
@@ -370,14 +358,12 @@ namespace Avalonia.Controls
                 }
             }
         }
-
-        /// <inheritdoc/>
+        
         protected override void OnPointerCaptureLost(PointerCaptureLostEventArgs e)
         {
             IsPressed = false;
         }
 
-        /// <inheritdoc/>
         protected override void OnLostFocus(RoutedEventArgs e)
         {
             base.OnLostFocus(e);
@@ -385,7 +371,6 @@ namespace Avalonia.Controls
             IsPressed = false;
         }
 
-        /// <inheritdoc/>
         protected override void OnPropertyChanged<T>(AvaloniaPropertyChangedEventArgs<T> change)
         {
             base.OnPropertyChanged(change);
@@ -406,7 +391,6 @@ namespace Avalonia.Controls
             }
         }
 
-        /// <inheritdoc/>
         protected override void UpdateDataValidation<T>(AvaloniaProperty<T> property, BindingValue<T> value)
         {
             base.UpdateDataValidation(property, value);
@@ -509,7 +493,7 @@ namespace Avalonia.Controls
         /// </summary>
         /// <param name="sender">The event sender.</param>
         /// <param name="e">The event args.</param>
-        public void CanExecuteChanged(object sender, EventArgs e)
+        private void CanExecuteChanged(object sender, EventArgs e)
         {
             var canExecute = Command == null || Command.CanExecute(CommandParameter);
 
@@ -582,12 +566,11 @@ namespace Avalonia.Controls
             }
         }
 
-        /// <summary>
-        /// Updates the visual state of the control by applying latest PseudoClasses.
-        /// </summary>
         private void UpdatePseudoClasses(bool isPressed)
         {
             PseudoClasses.Set(":pressed", isPressed);
         }
+
+        void ICommandSource.CanExecuteChanged(object sender, EventArgs e) => this.CanExecuteChanged(sender, e);
     }
 }

From 1605d3a702efa393b7ff5324db52869b59662c04 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Thu, 27 Jan 2022 11:30:16 -0500
Subject: [PATCH 33/48] Add back wanted SplitButton changes after reverting
 commits

---
 src/Avalonia.Controls/SplitButton/SplitButton.cs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index 6391812bed..13d3572975 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -271,12 +271,12 @@ namespace Avalonia.Controls
                 if (_isAttachedToLogicalTree)
                 {
                     // Must unregister events here while a reference to the old command still exists
-                    if (e.OldValue is ICommand oldCommand)
+                    if (e.OldValue.GetValueOrDefault() is ICommand oldCommand)
                     {
                         oldCommand.CanExecuteChanged -= CanExecuteChanged;
                     }
 
-                    if (e.NewValue is ICommand newCommand)
+                    if (e.NewValue.GetValueOrDefault() is ICommand newCommand)
                     {
                         newCommand.CanExecuteChanged += CanExecuteChanged;
                     }

From 37c31bbd89b100ed566cf919fac75b2f0f689182 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Thu, 27 Jan 2022 11:46:32 -0500
Subject: [PATCH 34/48] Fixed some formatting and comments

---
 src/Avalonia.Controls/SplitButton/SplitButton.cs | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index 13d3572975..f7b629989b 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -15,8 +15,8 @@ namespace Avalonia.Controls
     [PseudoClasses(pcFlyoutOpen)]
     public class SplitButton : ContentControl, ICommandSource
     {
-        private const string pcFlyoutOpen        = ":flyout-open";
-        protected const string pcChecked = ":checked";
+        protected const string pcChecked    = ":checked";
+        protected const string pcFlyoutOpen = ":flyout-open";
 
         /// <summary>
         /// Raised when the user presses the primary part of the <see cref="SplitButton"/>.
@@ -27,6 +27,9 @@ namespace Avalonia.Controls
             remove => RemoveHandler(ClickEvent, value);
         }
 
+        /// <summary>
+        /// Defines the <see cref="Click"/> event.
+        /// </summary>
         public static readonly RoutedEvent<RoutedEventArgs> ClickEvent = Button.ClickEvent;
 
         /// <summary>
@@ -54,11 +57,11 @@ namespace Avalonia.Controls
         private Button _primaryButton   = null;
         private Button _secondaryButton = null;
 
-        private bool        _commandCanExecute       = true;
-        private bool        _isAttachedToLogicalTree = false;
-        private bool        _isFlyoutOpen            = false;
+        private bool _commandCanExecute       = true;
+        private bool _isAttachedToLogicalTree = false;
+        private bool _isFlyoutOpen            = false;
 
-        private IDisposable         _flyoutPropertyChangedDisposable;
+        private IDisposable _flyoutPropertyChangedDisposable;
 
         ////////////////////////////////////////////////////////////////////////
         // Constructor / Destructors

From 4dddf123923cb7b07ed5f3a0a67548a5587b8b41 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Thu, 27 Jan 2022 11:49:50 -0500
Subject: [PATCH 35/48] Use InternalIsChecked

---
 src/Avalonia.Controls/SplitButton/SplitButton.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index f7b629989b..8b0a2c0f58 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -140,7 +140,7 @@ namespace Avalonia.Controls
         protected void UpdatePseudoClasses()
         {
             PseudoClasses.Set(pcFlyoutOpen, _isFlyoutOpen);
-            PseudoClasses.Set(pcChecked, GetValue(ToggleSplitButton.IsCheckedProperty));
+            PseudoClasses.Set(pcChecked, InternalIsChecked);
         }
 
         /// <summary>

From f03b2f64f9e42356fbcaa9fcf868e67bdda39503 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Thu, 27 Jan 2022 11:52:38 -0500
Subject: [PATCH 36/48] Require Alt+Down to open flyout (closer to WinUI now)

---
 src/Avalonia.Controls/SplitButton/SplitButton.cs | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index 8b0a2c0f58..1dcd5744c8 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -351,11 +351,8 @@ namespace Avalonia.Controls
                     e.Handled = true;
                 }
             }
-            else if (key == Key.Down && IsEffectivelyEnabled)
+            else if (key == Key.Down && e.KeyModifiers.HasAllFlags(KeyModifiers.Alt) && IsEffectivelyEnabled)
             {
-                // WinUI requires the VirtualKey.Menu (alt) + VirtualKey.Down to open the flyout
-                // Avalonia will only require Key.Down which is better cross-platform
-
                 OpenFlyout();
                 e.Handled = true;
             }

From 94de79f243917e85122ce05b0618ddd9c00ffb1c Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Thu, 27 Jan 2022 13:35:43 -0500
Subject: [PATCH 37/48] Remove SplitButtonSecondaryButtonIconGeometry resource

---
 src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index d0ddcdb2aa..3425485540 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -22,7 +22,6 @@
   <Styles.Resources>
     <x:Double x:Key="SplitButtonPrimaryButtonSize">32</x:Double>
     <x:Double x:Key="SplitButtonSecondaryButtonSize">32</x:Double>
-    <StreamGeometry x:Key="SplitButtonSecondaryButtonIconGeometry">M1939 486L2029 576L1024 1581L19 576L109 486L1024 1401L1939 486Z</StreamGeometry>
   </Styles.Resources>
 
   <Style Selector="SplitButton">
@@ -99,7 +98,7 @@
       <Template>
         <PathIcon Height="12"
                   Width="12"
-                  Data="{StaticResource SplitButtonSecondaryButtonIconGeometry}" />
+                  Data="M1939 486L2029 576L1024 1581L19 576L109 486L1024 1401L1939 486Z" />
       </Template>
     </Setter>
   </Style>

From 777cea8c43c68d22890cd8965f80e0792d7c816f Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Thu, 27 Jan 2022 13:48:34 -0500
Subject: [PATCH 38/48] Hide ICommandSource.CanExecuteChanged publicly like
 Button

---
 src/Avalonia.Controls/SplitButton/SplitButton.cs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index 1dcd5744c8..a85d34537f 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -123,7 +123,10 @@ namespace Avalonia.Controls
         ////////////////////////////////////////////////////////////////////////
 
         /// <inheritdoc/>
-        public void CanExecuteChanged(object sender, EventArgs e)
+        void ICommandSource.CanExecuteChanged(object sender, EventArgs e) => this.CanExecuteChanged(sender, e);
+
+        /// <inheritdoc cref="ICommandSource.CanExecuteChanged"/>
+        private void CanExecuteChanged(object sender, EventArgs e)
         {
             var canExecute = Command == null || Command.CanExecute(CommandParameter);
 

From f039511de22dde9eeae23346d3815e18d2ff48c2 Mon Sep 17 00:00:00 2001
From: Max Katz <maxkatz6@outlook.com>
Date: Wed, 2 Feb 2022 00:43:37 -0500
Subject: [PATCH 39/48] Adjust nullability

---
 src/Avalonia.Controls/Button.cs               |  6 +--
 .../SplitButton/SplitButton.cs                | 38 +++++++++----------
 .../SplitButton/ToggleSplitButton.cs          |  2 +-
 3 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/src/Avalonia.Controls/Button.cs b/src/Avalonia.Controls/Button.cs
index a2efc7fba0..a7a4759182 100644
--- a/src/Avalonia.Controls/Button.cs
+++ b/src/Avalonia.Controls/Button.cs
@@ -85,8 +85,8 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="Flyout"/> property
         /// </summary>
-        public static readonly StyledProperty<FlyoutBase> FlyoutProperty =
-            AvaloniaProperty.Register<Button, FlyoutBase>(nameof(Flyout));
+        public static readonly StyledProperty<FlyoutBase?> FlyoutProperty =
+            AvaloniaProperty.Register<Button, FlyoutBase?>(nameof(Flyout));
 
         private ICommand? _command;
         private bool _commandCanExecute = true;
@@ -186,7 +186,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets the Flyout that should be shown with this button.
         /// </summary>
-        public FlyoutBase Flyout
+        public FlyoutBase? Flyout
         {
             get => GetValue(FlyoutProperty);
             set => SetValue(FlyoutProperty, value);
diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index a85d34537f..8e32d46820 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -35,7 +35,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="Command"/> property.
         /// </summary>
-        public static readonly DirectProperty<SplitButton, ICommand> CommandProperty =
+        public static readonly DirectProperty<SplitButton, ICommand?> CommandProperty =
             Button.CommandProperty.AddOwner<SplitButton>(
                 splitButton => splitButton.Command,
                 (splitButton, command) => splitButton.Command = command);
@@ -43,25 +43,25 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="CommandParameter"/> property.
         /// </summary>
-        public static readonly StyledProperty<object> CommandParameterProperty =
+        public static readonly StyledProperty<object?> CommandParameterProperty =
             Button.CommandParameterProperty.AddOwner<SplitButton>();
 
         /// <summary>
         /// Defines the <see cref="Flyout"/> property
         /// </summary>
-        public static readonly StyledProperty<FlyoutBase> FlyoutProperty =
+        public static readonly StyledProperty<FlyoutBase?> FlyoutProperty =
             Button.FlyoutProperty.AddOwner<SplitButton>();
 
-        private ICommand _Command;
+        private ICommand? _Command;
 
-        private Button _primaryButton   = null;
-        private Button _secondaryButton = null;
+        private Button? _primaryButton   = null;
+        private Button? _secondaryButton = null;
 
         private bool _commandCanExecute       = true;
         private bool _isAttachedToLogicalTree = false;
         private bool _isFlyoutOpen            = false;
 
-        private IDisposable _flyoutPropertyChangedDisposable;
+        private IDisposable? _flyoutPropertyChangedDisposable;
 
         ////////////////////////////////////////////////////////////////////////
         // Constructor / Destructors
@@ -81,7 +81,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets the <see cref="ICommand"/> invoked when the primary part is pressed.
         /// </summary>
-        public ICommand Command
+        public ICommand? Command
         {
             get => _Command;
             set => SetAndRaise(CommandProperty, ref _Command, value);
@@ -90,7 +90,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets a parameter to be passed to the <see cref="Command"/>.
         /// </summary>
-        public object CommandParameter
+        public object? CommandParameter
         {
             get => GetValue(CommandParameterProperty);
             set => SetValue(CommandParameterProperty, value);
@@ -99,7 +99,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Gets or sets the <see cref="FlyoutBase"/> that is shown when the secondary part is pressed.
         /// </summary>
-        public FlyoutBase Flyout
+        public FlyoutBase? Flyout
         {
             get => GetValue(FlyoutProperty);
             set => SetValue(FlyoutProperty, value);
@@ -126,7 +126,7 @@ namespace Avalonia.Controls
         void ICommandSource.CanExecuteChanged(object sender, EventArgs e) => this.CanExecuteChanged(sender, e);
 
         /// <inheritdoc cref="ICommandSource.CanExecuteChanged"/>
-        private void CanExecuteChanged(object sender, EventArgs e)
+        private void CanExecuteChanged(object? sender, EventArgs e)
         {
             var canExecute = Command == null || Command.CanExecute(CommandParameter);
 
@@ -172,7 +172,7 @@ namespace Avalonia.Controls
         /// Registers all flyout events.
         /// </summary>
         /// <param name="flyout">The flyout to connect events to.</param>
-        private void RegisterFlyoutEvents(FlyoutBase flyout)
+        private void RegisterFlyoutEvents(FlyoutBase? flyout)
         {
             if (flyout != null)
             {
@@ -187,7 +187,7 @@ namespace Avalonia.Controls
         /// Explicitly unregisters all flyout events.
         /// </summary>
         /// <param name="flyout">The flyout to disconnect events from.</param>
-        private void UnregisterFlyoutEvents(FlyoutBase flyout)
+        private void UnregisterFlyoutEvents(FlyoutBase? flyout)
         {
             if (flyout != null)
             {
@@ -379,7 +379,7 @@ namespace Avalonia.Controls
         /// Invokes the <see cref="Click"/> event when the primary button part is clicked.
         /// </summary>
         /// <param name="e">The event args from the internal Click event.</param>
-        protected virtual void OnClickPrimary(RoutedEventArgs e)
+        protected virtual void OnClickPrimary(RoutedEventArgs? e)
         {
             // Note: It is not currently required to check enabled status; however, this is a failsafe
             if (IsEffectivelyEnabled)
@@ -399,7 +399,7 @@ namespace Avalonia.Controls
         /// Invoked when the secondary button part is clicked.
         /// </summary>
         /// <param name="e">The event args from the internal Click event.</param>
-        protected virtual void OnClickSecondary(RoutedEventArgs e)
+        protected virtual void OnClickSecondary(RoutedEventArgs? e)
         {
             // Note: It is not currently required to check enabled status; however, this is a failsafe
             if (IsEffectivelyEnabled)
@@ -415,7 +415,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Event handler for when the internal primary button part is pressed.
         /// </summary>
-        private void PrimaryButton_Click(object sender, RoutedEventArgs e)
+        private void PrimaryButton_Click(object? sender, RoutedEventArgs e)
         {
             OnClickPrimary(e);
         }
@@ -423,7 +423,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Event handler for when the internal secondary button part is pressed.
         /// </summary>
-        private void SecondaryButton_Click(object sender, RoutedEventArgs e)
+        private void SecondaryButton_Click(object? sender, RoutedEventArgs e)
         {
             OnClickSecondary(e);
         }
@@ -439,7 +439,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Event handler for when the split button's flyout is opened.
         /// </summary>
-        private void Flyout_Opened(object sender, EventArgs e)
+        private void Flyout_Opened(object? sender, EventArgs e)
         {
             var flyout = sender as FlyoutBase;
 
@@ -459,7 +459,7 @@ namespace Avalonia.Controls
         /// <summary>
         /// Event handler for when the split button's flyout is closed.
         /// </summary>
-        private void Flyout_Closed(object sender, EventArgs e)
+        private void Flyout_Closed(object? sender, EventArgs e)
         {
             var flyout = sender as FlyoutBase;
 
diff --git a/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs b/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
index c926250105..879c1aa6e1 100644
--- a/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/ToggleSplitButton.cs
@@ -115,7 +115,7 @@ namespace Avalonia.Controls
         }
 
         /// <inheritdoc/>
-        protected override void OnClickPrimary(RoutedEventArgs e)
+        protected override void OnClickPrimary(RoutedEventArgs? e)
         {
             Toggle();
 

From f10ced11eefda65259ec8448116ec983e37c218c Mon Sep 17 00:00:00 2001
From: Max Katz <maxkatz6@outlook.com>
Date: Wed, 2 Feb 2022 00:44:46 -0500
Subject: [PATCH 40/48] Use new RoutedEvent registration

---
 src/Avalonia.Controls/SplitButton/SplitButton.cs | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index 8e32d46820..4cacc2789f 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -30,7 +30,8 @@ namespace Avalonia.Controls
         /// <summary>
         /// Defines the <see cref="Click"/> event.
         /// </summary>
-        public static readonly RoutedEvent<RoutedEventArgs> ClickEvent = Button.ClickEvent;
+        public static readonly RoutedEvent<RoutedEventArgs> ClickEvent =
+            RoutedEvent.Register<SplitButton, RoutedEventArgs>(nameof(Click), RoutingStrategies.Bubble);
 
         /// <summary>
         /// Defines the <see cref="Command"/> property.
@@ -384,7 +385,7 @@ namespace Avalonia.Controls
             // Note: It is not currently required to check enabled status; however, this is a failsafe
             if (IsEffectivelyEnabled)
             {
-                var eventArgs = new RoutedEventArgs(Button.ClickEvent);
+                var eventArgs = new RoutedEventArgs(ClickEvent);
                 RaiseEvent(eventArgs);
 
                 if (!eventArgs.Handled && Command?.CanExecute(CommandParameter) == true)
@@ -417,6 +418,8 @@ namespace Avalonia.Controls
         /// </summary>
         private void PrimaryButton_Click(object? sender, RoutedEventArgs e)
         {
+            // Handle internal button click, so it won't bubble outside together with SplitButton.ClickEvent.
+            e.Handled = true;
             OnClickPrimary(e);
         }
 
@@ -425,6 +428,8 @@ namespace Avalonia.Controls
         /// </summary>
         private void SecondaryButton_Click(object? sender, RoutedEventArgs e)
         {
+            // Handle internal button click, so it won't bubble outside.
+            e.Handled = true;
             OnClickSecondary(e);
         }
 

From a50d606a5a51eb7fe052ad66944bf937863211dc Mon Sep 17 00:00:00 2001
From: Max Katz <maxkatz6@outlook.com>
Date: Wed, 2 Feb 2022 01:02:31 -0500
Subject: [PATCH 41/48] Add splitbutton pressed state back

---
 .../SplitButton/SplitButton.cs                |  8 ++++++-
 .../Controls/SplitButton.xaml                 | 22 +++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/Avalonia.Controls/SplitButton/SplitButton.cs b/src/Avalonia.Controls/SplitButton/SplitButton.cs
index 4cacc2789f..f1d07b2679 100644
--- a/src/Avalonia.Controls/SplitButton/SplitButton.cs
+++ b/src/Avalonia.Controls/SplitButton/SplitButton.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Windows.Input;
 using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Mixins;
 using Avalonia.Controls.Primitives;
 using Avalonia.Input;
 using Avalonia.Interactivity;
@@ -12,10 +13,11 @@ namespace Avalonia.Controls
     /// A button with primary and secondary parts that can each be pressed separately.
     /// The primary part behaves like a <see cref="Button"/> and the secondary part opens a flyout.
     /// </summary>
-    [PseudoClasses(pcFlyoutOpen)]
+    [PseudoClasses(pcFlyoutOpen, pcPressed)]
     public class SplitButton : ContentControl, ICommandSource
     {
         protected const string pcChecked    = ":checked";
+        protected const string pcPressed    = ":pressed";
         protected const string pcFlyoutOpen = ":flyout-open";
 
         /// <summary>
@@ -61,6 +63,7 @@ namespace Avalonia.Controls
         private bool _commandCanExecute       = true;
         private bool _isAttachedToLogicalTree = false;
         private bool _isFlyoutOpen            = false;
+        private bool _isKeyboardPressed       = false;
 
         private IDisposable? _flyoutPropertyChangedDisposable;
 
@@ -144,6 +147,7 @@ namespace Avalonia.Controls
         protected void UpdatePseudoClasses()
         {
             PseudoClasses.Set(pcFlyoutOpen, _isFlyoutOpen);
+            PseudoClasses.Set(pcPressed, _isKeyboardPressed);
             PseudoClasses.Set(pcChecked, InternalIsChecked);
         }
 
@@ -333,6 +337,7 @@ namespace Avalonia.Controls
 
             if (key == Key.Space || key == Key.Enter) // Key.GamepadA is not currently supported
             {
+                _isKeyboardPressed = true;
                 UpdatePseudoClasses();
             }
 
@@ -346,6 +351,7 @@ namespace Avalonia.Controls
 
             if (key == Key.Space || key == Key.Enter) // Key.GamepadA is not currently supported
             {
+                _isKeyboardPressed = false;
                 UpdatePseudoClasses();
 
                 // Consider this a click on the primary button
diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index 3425485540..bf192af673 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -125,6 +125,17 @@
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
 
+  <!-- SplitButton Pressed State -->
+  <Style Selector="SplitButton:pressed /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:pressed /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:pressed /template/ Button#PART_SecondaryButton PathIcon">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+
   <!-- Primary and Secondary buttons Flyout Open State -->
   <Style Selector="SplitButton:flyout-open /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
          SplitButton:flyout-open /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
@@ -180,6 +191,17 @@
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
 
+  <!-- SplitButton Checked Pressed State -->
+  <Style Selector="SplitButton:pressed:checked /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:pressed:checked /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
+    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:pressed:checked /template/ Button#PART_SecondaryButton PathIcon">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+
   <!-- Checked Flyout Open State -->
   <Style Selector="SplitButton:checked:flyout-open /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
          SplitButton:checked:flyout-open /template/ Button#PART_SecondaryButton /template/ ContentPresenter">

From 4327cb23c890dd8cbe74811dc32f39043630ca54 Mon Sep 17 00:00:00 2001
From: Max Katz <maxkatz6@outlook.com>
Date: Wed, 2 Feb 2022 01:08:30 -0500
Subject: [PATCH 42/48] Center splitbutton glyph

---
 src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index bf192af673..748fb64174 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -75,7 +75,8 @@
                     Foreground="{TemplateBinding Foreground}"
                     Background="{TemplateBinding Background}"
                     BorderThickness="{TemplateBinding BorderThickness}"
-                    HorizontalContentAlignment="Right"
+                    Padding="0"
+                    HorizontalContentAlignment="Center"
                     VerticalContentAlignment="Center"
                     HorizontalAlignment="Stretch"
                     VerticalAlignment="Stretch"
@@ -93,7 +94,6 @@
   </Style>
   <Style Selector="SplitButton /template/ Button#PART_SecondaryButton">
     <Setter Property="CornerRadius" Value="{TemplateBinding CornerRadius, Converter={StaticResource RightCornerRadiusFilterConverter}}" />
-    <Setter Property="Padding" Value="9,0" />
     <Setter Property="Content">
       <Template>
         <PathIcon Height="12"

From cb7663a08636f6975f33a36bacb0b1da7d90615e Mon Sep 17 00:00:00 2001
From: Max Katz <maxkatz6@outlook.com>
Date: Wed, 2 Feb 2022 23:35:17 -0500
Subject: [PATCH 43/48] Add separator border

---
 .../Controls/SplitButton.xaml                 | 86 ++++++++++++-------
 1 file changed, 53 insertions(+), 33 deletions(-)

diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index 748fb64174..60706e8c1e 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -1,6 +1,7 @@
 <Styles xmlns="https://github.com/avaloniaui"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-        x:CompileBindings="True">
+        x:CompileBindings="True"
+        xmlns:converters="using:Avalonia.Controls.Converters">
 
   <Design.PreviewWith>
     <Border Padding="60">
@@ -22,6 +23,10 @@
   <Styles.Resources>
     <x:Double x:Key="SplitButtonPrimaryButtonSize">32</x:Double>
     <x:Double x:Key="SplitButtonSecondaryButtonSize">32</x:Double>
+
+    <converters:MarginMultiplierConverter x:Key="PrimaryButtonBorderMultiplier" Left="True" Top="True" Bottom="True" Indent="1" />
+    <converters:MarginMultiplierConverter x:Key="SecondaryButtonBorderMultiplier" Right="True" Top="True" Bottom="True" Indent="1" />
+    <converters:MarginMultiplierConverter x:Key="SeparatorBorderMultiplier" Top="True" Bottom="True" Indent="1" />
   </Styles.Resources>
 
   <Style Selector="SplitButton">
@@ -44,6 +49,7 @@
             <Grid.ColumnDefinitions>
               <ColumnDefinition Width="*" />
               <ColumnDefinition Width="Auto" />
+              <ColumnDefinition Width="Auto" />
             </Grid.ColumnDefinitions>
 
             <Button x:Name="PART_PrimaryButton"
@@ -51,7 +57,7 @@
                     MinWidth="{DynamicResource SplitButtonPrimaryButtonSize}"
                     Foreground="{TemplateBinding Foreground}"
                     Background="{TemplateBinding Background}"
-                    BorderThickness="{TemplateBinding BorderThickness}"
+                    BorderThickness="{TemplateBinding BorderThickness, Converter={StaticResource PrimaryButtonBorderMultiplier}}"
                     BorderBrush="{TemplateBinding BorderBrush}"
                     Content="{TemplateBinding Content}"
                     ContentTemplate="{TemplateBinding ContentTemplate}"
@@ -68,13 +74,20 @@
                     Focusable="False"
                     KeyboardNavigation.IsTabStop="False" />
 
-            <Button x:Name="PART_SecondaryButton"
+            <Border x:Name="SeparatorBorder"
                     Grid.Column="1"
+                    Background="Transparent"
+                    Width="1"
+                    BorderThickness="{TemplateBinding BorderThickness, Converter={StaticResource SeparatorBorderMultiplier}}"
+                    BorderBrush="{TemplateBinding BorderBrush}" />
+
+            <Button x:Name="PART_SecondaryButton"
+                    Grid.Column="2"
                     MinWidth="{DynamicResource SplitButtonSecondaryButtonSize}"
                     BorderBrush="{TemplateBinding BorderBrush}"
                     Foreground="{TemplateBinding Foreground}"
                     Background="{TemplateBinding Background}"
-                    BorderThickness="{TemplateBinding BorderThickness}"
+                    BorderThickness="{TemplateBinding BorderThickness, Converter={StaticResource SecondaryButtonBorderMultiplier}}"
                     Padding="0"
                     HorizontalContentAlignment="Center"
                     VerticalContentAlignment="Center"
@@ -106,8 +119,8 @@
   <!-- Primary and Secondary buttons PointerOver State -->
   <Style Selector="SplitButton /template/ Button#PART_PrimaryButton:pointerover /template/ ContentPresenter,
          SplitButton /template/ Button#PART_SecondaryButton:pointerover /template/ ContentPresenter">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
     <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
   </Style>
   <Style Selector="SplitButton /template/ Button#PART_SecondaryButton:pointerover PathIcon">
@@ -117,8 +130,8 @@
   <!-- Primary and Secondary buttons Pressed State -->
   <Style Selector="SplitButton /template/ Button#PART_PrimaryButton:pressed /template/ ContentPresenter,
          SplitButton /template/ Button#PART_SecondaryButton:pressed /template/ ContentPresenter">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
     <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
   <Style Selector="SplitButton /template/ Button#PART_SecondaryButton:pressed PathIcon">
@@ -127,9 +140,10 @@
 
   <!-- SplitButton Pressed State -->
   <Style Selector="SplitButton:pressed /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
-         SplitButton:pressed /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+         SplitButton:pressed /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:pressed /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
     <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
   <Style Selector="SplitButton:pressed /template/ Button#PART_SecondaryButton PathIcon">
@@ -138,9 +152,10 @@
 
   <!-- Primary and Secondary buttons Flyout Open State -->
   <Style Selector="SplitButton:flyout-open /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
-         SplitButton:flyout-open /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+         SplitButton:flyout-open /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:flyout-open /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
     <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
   <Style Selector="SplitButton:flyout-open /template/ Button#PART_SecondaryButton PathIcon">
@@ -149,9 +164,10 @@
 
   <!-- Disabled State -->
   <Style Selector="SplitButton:disabled /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
-         SplitButton:disabled /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundDisabled}" />
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushDisabled}" />
+         SplitButton:disabled /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:disabled /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundDisabled}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushDisabled}" />
     <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundDisabled}" />
   </Style>
   <Style Selector="SplitButton:disabled /template/ Button#PART_SecondaryButton PathIcon">
@@ -160,9 +176,10 @@
 
   <!-- Checked State -->
   <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
-         SplitButton:checked /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+         SplitButton:checked /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:checked /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
     <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
   <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton PathIcon">
@@ -172,8 +189,8 @@
   <!-- Checked PointerOver State -->
   <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton:pointerover /template/ ContentPresenter,
          SplitButton:checked /template/ Button#PART_SecondaryButton:pointerover /template/ ContentPresenter">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
     <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
   </Style>
   <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton:pointerover PathIcon">
@@ -183,8 +200,8 @@
   <!-- Checked Pressed State -->
   <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton:pressed /template/ ContentPresenter,
          SplitButton:checked /template/ Button#PART_SecondaryButton:pressed /template/ ContentPresenter">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
     <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
   <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton:pressed PathIcon">
@@ -193,9 +210,10 @@
 
   <!-- SplitButton Checked Pressed State -->
   <Style Selector="SplitButton:pressed:checked /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
-         SplitButton:pressed:checked /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+         SplitButton:pressed:checked /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:pressed:checked /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
     <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
   <Style Selector="SplitButton:pressed:checked /template/ Button#PART_SecondaryButton PathIcon">
@@ -204,9 +222,10 @@
 
   <!-- Checked Flyout Open State -->
   <Style Selector="SplitButton:checked:flyout-open /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
-         SplitButton:checked:flyout-open /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+         SplitButton:checked:flyout-open /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:checked:flyout-open /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
     <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
   <Style Selector="SplitButton:checked:flyout-open /template/ Button#PART_SecondaryButton PathIcon">
@@ -215,9 +234,10 @@
 
   <!-- Disabled Checked State -->
   <Style Selector="SplitButton:checked:disabled /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
-         SplitButton:checked:disabled /template/ Button#PART_SecondaryButton /template/ ContentPresenter">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedDisabled}" />
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedDisabled}" />
+         SplitButton:checked:disabled /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:checked:disabled /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundCheckedDisabled}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedDisabled}" />
     <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedDisabled}" />
   </Style>
   <Style Selector="SplitButton:checked:disabled /template/ Button#PART_SecondaryButton PathIcon">

From 21612e9daf5592b031bcfcbb1d4ce18915906c64 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Sat, 5 Feb 2022 00:43:02 -0500
Subject: [PATCH 44/48] Add SplitButtonSeparatorWidth resource

---
 src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
index 60706e8c1e..e0dd0180b3 100644
--- a/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/SplitButton.xaml
@@ -23,6 +23,7 @@
   <Styles.Resources>
     <x:Double x:Key="SplitButtonPrimaryButtonSize">32</x:Double>
     <x:Double x:Key="SplitButtonSecondaryButtonSize">32</x:Double>
+    <x:Double x:Key="SplitButtonSeparatorWidth">1</x:Double>
 
     <converters:MarginMultiplierConverter x:Key="PrimaryButtonBorderMultiplier" Left="True" Top="True" Bottom="True" Indent="1" />
     <converters:MarginMultiplierConverter x:Key="SecondaryButtonBorderMultiplier" Right="True" Top="True" Bottom="True" Indent="1" />
@@ -77,7 +78,7 @@
             <Border x:Name="SeparatorBorder"
                     Grid.Column="1"
                     Background="Transparent"
-                    Width="1"
+                    Width="{DynamicResource SplitButtonSeparatorWidth}"
                     BorderThickness="{TemplateBinding BorderThickness, Converter={StaticResource SeparatorBorderMultiplier}}"
                     BorderBrush="{TemplateBinding BorderBrush}" />
 

From cd16f3a89bc4a5c9f412b756dcdb5ad94cf1de8d Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Sat, 5 Feb 2022 00:43:43 -0500
Subject: [PATCH 45/48] Update SplitButton in the default theme

---
 .../Controls/SplitButton.xaml                 | 501 ++++++------------
 1 file changed, 169 insertions(+), 332 deletions(-)

diff --git a/src/Avalonia.Themes.Default/Controls/SplitButton.xaml b/src/Avalonia.Themes.Default/Controls/SplitButton.xaml
index a4f3e16673..21ce9b61b8 100644
--- a/src/Avalonia.Themes.Default/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Default/Controls/SplitButton.xaml
@@ -1,6 +1,7 @@
 <Styles xmlns="https://github.com/avaloniaui"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-        x:CompileBindings="True">
+        x:CompileBindings="True"
+        xmlns:converters="using:Avalonia.Controls.Converters">
 
   <!-- This style is heavily based on the Fluent v1 style.
        The base resources are switched out along with a few minor changes such as Padding, CornerRadius. -->
@@ -12,10 +13,15 @@
   </Design.PreviewWith>
 
   <Styles.Resources>
-    <x:Double x:Key="SplitButtonPrimaryButtonSize">32</x:Double>
-    <GridLength x:Key="SplitButtonSecondaryButtonSize">32</GridLength>
+    <x:Double x:Key="SplitButtonPrimaryButtonSize">24</x:Double>
+    <x:Double x:Key="SplitButtonSecondaryButtonSize">24</x:Double>
+    <x:Double x:Key="SplitButtonSeparatorWidth">1</x:Double>
     <Thickness x:Key="SplitButtonBorderThemeThickness">1</Thickness>
-    
+
+    <converters:MarginMultiplierConverter x:Key="PrimaryButtonBorderMultiplier" Left="True" Top="True" Bottom="True" Indent="1" />
+    <converters:MarginMultiplierConverter x:Key="SecondaryButtonBorderMultiplier" Right="True" Top="True" Bottom="True" Indent="1" />
+    <converters:MarginMultiplierConverter x:Key="SeparatorBorderMultiplier" Top="True" Bottom="True" Indent="1" />
+
     <StaticResource x:Key="SplitButtonBackground" ResourceKey="ThemeControlMidBrush" />
     <StaticResource x:Key="SplitButtonBackgroundPointerOver" ResourceKey="ThemeControlMidBrush" />
     <StaticResource x:Key="SplitButtonBackgroundPressed" ResourceKey="ThemeControlHighBrush" />
@@ -51,380 +57,211 @@
     <Setter Property="BorderThickness" Value="{DynamicResource SplitButtonBorderThemeThickness}" />
     <Setter Property="HorizontalAlignment" Value="Left" />
     <Setter Property="VerticalAlignment" Value="Center" />
-    <!--<Setter Property="FontFamily" Value="{ThemeResource ContentControlThemeFontFamily}" />
-    <Setter Property="FontWeight" Value="Normal" />
-    <Setter Property="FontSize" Value="{ThemeResource ControlContentThemeFontSize}" />
-    <Setter Property="UseSystemFocusVisuals" Value="True" />
+    <!--<Setter Property="UseSystemFocusVisuals" Value="True" />
     <Setter Property="FocusVisualMargin" Value="-3" />-->
     <Setter Property="KeyboardNavigation.IsTabStop" Value="True" />
+    <Setter Property="Focusable" Value="True" />
     <Setter Property="Padding" Value="4" />
     <Setter Property="CornerRadius" Value="0" />
     <Setter Property="Template">
       <Setter.Value>
         <ControlTemplate>
-          <!-- A Border was added here since Avalonia does not support Background/Border/CornerRadius on Grid directly
-               This also allowed removing the extra background border and integrating it here. -->
-          <Border x:Name="RootBorder"
-                  Background="Transparent"
-                  BorderBrush="{TemplateBinding BorderBrush}"
-                  BorderThickness="{TemplateBinding BorderThickness}"
-                  CornerRadius="{TemplateBinding CornerRadius}">
-            <!-- In WinUI, a separate child style for the inner buttons is provided here.
-                 For avalonia that style is simplified and pulled out separately below.
-                 A style is needed to override any button default background/foreground/border colors, etc. -->
-            <Grid>
-              
-              <Grid.ColumnDefinitions>
-                <ColumnDefinition Width="*"
-                                  MinWidth="{StaticResource SplitButtonPrimaryButtonSize}" />
-                <ColumnDefinition Width="1" />
-                <ColumnDefinition Width="{StaticResource SplitButtonSecondaryButtonSize}" />
-              </Grid.ColumnDefinitions>
+          <Grid>
+            <Grid.ColumnDefinitions>
+              <ColumnDefinition Width="*" />
+              <ColumnDefinition Width="Auto" />
+              <ColumnDefinition Width="Auto" />
+            </Grid.ColumnDefinitions>
 
-              <!-- Changed from Grid to Border since Avalonia does not support Background/CornerRadius on Grid directly -->
-              <Border x:Name="PrimaryBackgroundBorder"
-                      Background="{TemplateBinding Background}"
-                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource LeftCornerRadiusFilterConverter}}" />
+            <Button x:Name="PART_PrimaryButton"
+                    Grid.Column="0"
+                    MinWidth="{DynamicResource SplitButtonPrimaryButtonSize}"
+                    Foreground="{TemplateBinding Foreground}"
+                    Background="{TemplateBinding Background}"
+                    BorderThickness="{TemplateBinding BorderThickness, Converter={StaticResource PrimaryButtonBorderMultiplier}}"
+                    BorderBrush="{TemplateBinding BorderBrush}"
+                    Content="{TemplateBinding Content}"
+                    ContentTemplate="{TemplateBinding ContentTemplate}"
+                    Command="{TemplateBinding Command}"
+                    CommandParameter="{TemplateBinding CommandParameter}"
+                    FontFamily="{TemplateBinding FontFamily}"
+                    FontSize="{TemplateBinding FontSize}"
+                    FontWeight="{TemplateBinding FontWeight}"
+                    HorizontalAlignment="Stretch"
+                    VerticalAlignment="Stretch"
+                    HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
+                    VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
+                    Padding="{TemplateBinding Padding}"
+                    Focusable="False"
+                    KeyboardNavigation.IsTabStop="False" />
 
-              <Border x:Name="SecondaryBackgroundBorder"
-                      Background="{TemplateBinding Background}"
-                      Grid.Column="2"
-                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource RightCornerRadiusFilterConverter}}" />
+            <Border x:Name="SeparatorBorder"
+                    Grid.Column="1"
+                    Background="Transparent"
+                    Width="{DynamicResource SplitButtonSeparatorWidth}"
+                    BorderThickness="{TemplateBinding BorderThickness, Converter={StaticResource SeparatorBorderMultiplier}}"
+                    BorderBrush="{TemplateBinding BorderBrush}" />
 
-              <Button x:Name="PART_PrimaryButton"
-                      Grid.Column="0"
-                      Foreground="{TemplateBinding Foreground}"
-                      Background="{TemplateBinding Background}"
-                      BorderThickness="{TemplateBinding BorderThickness}"
-                      BorderBrush="Transparent"
-                      Content="{TemplateBinding Content}"
-                      ContentTemplate="{TemplateBinding ContentTemplate}"
-                      Command="{TemplateBinding Command}"
-                      CommandParameter="{TemplateBinding CommandParameter}"
-                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource LeftCornerRadiusFilterConverter}}"
-                      FontFamily="{TemplateBinding FontFamily}"
-                      FontSize="{TemplateBinding FontSize}"
-                      FontWeight="{TemplateBinding FontWeight}"
-                      HorizontalAlignment="Stretch"
-                      VerticalAlignment="Stretch"
-                      HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
-                      VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}"
-                      Padding="{TemplateBinding Padding}"
-                      KeyboardNavigation.IsTabStop="False" />
-
-              <Button x:Name="PART_SecondaryButton"
-                      Grid.Column="2"
-                      CornerRadius="{Binding $parent[SplitButton].CornerRadius, Converter={StaticResource RightCornerRadiusFilterConverter}}"
-                      Foreground="{TemplateBinding Foreground}"
-                      Background="{TemplateBinding Background}"
-                      BorderThickness="{TemplateBinding BorderThickness}"
-                      BorderBrush="Transparent"
-                      HorizontalContentAlignment="Right"
-                      VerticalContentAlignment="Center"
-                      HorizontalAlignment="Stretch"
-                      VerticalAlignment="Stretch"
-                      KeyboardNavigation.IsTabStop="False"
-                      Padding="0,0,10,0">
-                <Button.Content>
-                  <!-- TextBlock converted to a Path and placed within Viewbox -->
-                  <Viewbox UseLayoutRounding="False"
-                           IsHitTestVisible="False"
-                           Height="12"
-                           Width="12">
-                    <Path x:Name="DropDownGlyphPath"
-                          VerticalAlignment="Center"
-                          HorizontalAlignment="Right"
-                          Fill="{TemplateBinding Foreground}"
-                          Data="M1939 486L2029 576L1024 1581L19 576L109 486L1024 1401L1939 486Z"
-                          Stretch="Uniform" />
-                  </Viewbox>
-                </Button.Content>
-              </Button>
-            </Grid>
-          </Border>
+            <Button x:Name="PART_SecondaryButton"
+                    Grid.Column="2"
+                    MinWidth="{DynamicResource SplitButtonSecondaryButtonSize}"
+                    BorderBrush="{TemplateBinding BorderBrush}"
+                    Foreground="{TemplateBinding Foreground}"
+                    Background="{TemplateBinding Background}"
+                    BorderThickness="{TemplateBinding BorderThickness, Converter={StaticResource SecondaryButtonBorderMultiplier}}"
+                    Padding="0"
+                    HorizontalContentAlignment="Center"
+                    VerticalContentAlignment="Center"
+                    HorizontalAlignment="Stretch"
+                    VerticalAlignment="Stretch"
+                    Focusable="False"
+                    KeyboardNavigation.IsTabStop="False" />
+          </Grid>
         </ControlTemplate>
       </Setter.Value>
     </Setter>
   </Style>
 
-  <!-- Normal State (not a PseudoClass) -->
-  <!-- The 'Button' style here was moved out of the main style above.
-       In WinUI there is a child, customized style shared for both primary and secondary buttons.
-       In Avalonia, we can use selectors to make a 'normal' style apply only to those buttons but
-       pull it out separately from the full style above. -->
-  <Style Selector="SplitButton /template/ Button">
-    <!-- Applies to both Primary/Secondary buttons -->
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForeground}" />
-    <Setter Property="BorderBrush" Value="Transparent" />
-    <Setter Property="BorderThickness" Value="{DynamicResource SplitButtonBorderThemeThickness}" />
-    <Setter Property="Template">
-      <ControlTemplate>
-        <!-- Switched from Grid to Border to optimize and support Foreground/Background properties -->
-        <!-- It is important for the background to be clear and no CornerRadius set. -->
-        <Border Background="Transparent">
-          <ContentPresenter x:Name="ContentPresenter"
-                            BorderBrush="{TemplateBinding BorderBrush}"
-                            BorderThickness="{TemplateBinding BorderThickness}"
-                            Content="{TemplateBinding Content}"
-                            ContentTemplate="{TemplateBinding ContentTemplate}"
-                            Padding="{TemplateBinding Padding}"
-                            HorizontalContentAlignment="{TemplateBinding HorizontalContentAlignment}"
-                            VerticalContentAlignment="{TemplateBinding VerticalContentAlignment}" />
-        </Border>
-      </ControlTemplate>
+  <!-- Default overridable styles -->
+  <Style Selector="SplitButton /template/ Button#PART_PrimaryButton">
+    <Setter Property="CornerRadius" Value="{TemplateBinding CornerRadius, Converter={StaticResource LeftCornerRadiusFilterConverter}}" />
+  </Style>
+  <Style Selector="SplitButton /template/ Button#PART_SecondaryButton">
+    <Setter Property="CornerRadius" Value="{TemplateBinding CornerRadius, Converter={StaticResource RightCornerRadiusFilterConverter}}" />
+    <Setter Property="Content">
+      <Template>
+        <PathIcon Height="12"
+                  Width="12"
+                  Data="M1939 486L2029 576L1024 1581L19 576L109 486L1024 1401L1939 486Z" />
+      </Template>
     </Setter>
   </Style>
 
-  <!-- Disabled State -->
-  <Style Selector="SplitButton:disabled /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushDisabled}" />
-  </Style>
-  <Style Selector="SplitButton:disabled /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundDisabled}" />
-  </Style>
-  <Style Selector="SplitButton:disabled /template/ Button">
-    <!-- Applies to both Primary/Secondary buttons -->
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundDisabled}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundDisabled}" />
+  <!-- Primary and Secondary buttons PointerOver State -->
+  <Style Selector="SplitButton /template/ Button#PART_PrimaryButton:pointerover /template/ ContentPresenter,
+         SplitButton /template/ Button#PART_SecondaryButton:pointerover /template/ ContentPresenter">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton /template/ Button#PART_SecondaryButton:pointerover PathIcon">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
   </Style>
 
-  <!-- FlyoutOpen State -->
-  <Style Selector="SplitButton:flyout-open /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:flyout-open /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:flyout-open /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
-  </Style>
-  <Style Selector="SplitButton:flyout-open /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:flyout-open /template/ Button#PART_SecondaryButton">
+  <!-- Primary and Secondary buttons Pressed State -->
+  <Style Selector="SplitButton /template/ Button#PART_PrimaryButton:pressed /template/ ContentPresenter,
+         SplitButton /template/ Button#PART_SecondaryButton:pressed /template/ ContentPresenter">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton /template/ Button#PART_SecondaryButton:pressed PathIcon">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
 
-  <!-- TouchPressed State -->
-  <Style Selector="SplitButton:touch-pressed /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:touch-pressed /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:touch-pressed /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
-  </Style>
-  <Style Selector="SplitButton:touch-pressed /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:touch-pressed /template/ Button#PART_SecondaryButton">
+  <!-- SplitButton Pressed State -->
+  <Style Selector="SplitButton:pressed /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:pressed /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:pressed /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:pressed /template/ Button#PART_SecondaryButton PathIcon">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
 
-  <!-- PrimaryPointerOver State -->
-  <Style Selector="SplitButton:primary-pointerover /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
-  </Style>
-  <Style Selector="SplitButton:primary-pointerover /template/ Button#PART_PrimaryButton">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
-  </Style>
-  <Style Selector="SplitButton:primary-pointerover /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
-  </Style>
-
-  <!-- PrimaryPressed State -->
-  <Style Selector="SplitButton:primary-pressed /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:primary-pressed /template/ Button#PART_PrimaryButton">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+  <!-- Primary and Secondary buttons Flyout Open State -->
+  <Style Selector="SplitButton:flyout-open /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:flyout-open /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:flyout-open /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  </Style>
+  <Style Selector="SplitButton:flyout-open /template/ Button#PART_SecondaryButton PathIcon">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
   </Style>
-  <Style Selector="SplitButton:primary-pressed /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
-  </Style>
 
-  <!-- SecondaryPointerOver State -->
-  <Style Selector="SplitButton:secondary-pointerover /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
-  </Style>
-  <Style Selector="SplitButton:secondary-pointerover /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPointerOver}" />
-  </Style>
-  <Style Selector="SplitButton:secondary-pointerover /template/ Button#PART_SecondaryButton">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPointerOver}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPointerOver}" />
-  </Style>
-
-  <!-- SecondaryPressed State -->
-  <Style Selector="SplitButton:secondary-pressed /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackground}" />
-  </Style>
-  <Style Selector="SplitButton:secondary-pressed /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundPressed}" />
-  </Style>
-  <Style Selector="SplitButton:secondary-pressed /template/ Button#PART_SecondaryButton">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushPressed}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundPressed}" />
+  <!-- Disabled State -->
+  <Style Selector="SplitButton:disabled /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:disabled /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:disabled /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundDisabled}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushDisabled}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundDisabled}" />
+  </Style>
+  <Style Selector="SplitButton:disabled /template/ Button#PART_SecondaryButton PathIcon">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundDisabled}" />
   </Style>
 
   <!-- Checked State -->
-  <Style Selector="SplitButton:checked /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton">
+  <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:checked /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:checked /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
+  </Style>
+  <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton PathIcon">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
   </Style>
-  <Style Selector="SplitButton:checked /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
-
-  <!-- CheckedFlyoutOpen State -->
-  <Style Selector="SplitButton:checked-flyout-open /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Button#PART_SecondaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-flyout-open /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
-
-  <!-- CheckedTouchPressed State -->
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Button#PART_SecondaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-touch-pressed /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
 
-  <!-- CheckedPrimaryPointerOver State -->
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#PART_PrimaryButton">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
+  <!-- Checked PointerOver State -->
+  <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton:pointerover /template/ ContentPresenter,
+         SplitButton:checked /template/ Button#PART_SecondaryButton:pointerover /template/ ContentPresenter">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
+  </Style>
+  <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton:pointerover PathIcon">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
   </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Button#PART_SecondaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pointerover /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
 
-  <!-- CheckedPrimaryPressed State -->
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Button#PART_PrimaryButton">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+  <!-- Checked Pressed State -->
+  <Style Selector="SplitButton:checked /template/ Button#PART_PrimaryButton:pressed /template/ ContentPresenter,
+         SplitButton:checked /template/ Button#PART_SecondaryButton:pressed /template/ ContentPresenter">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked /template/ Button#PART_SecondaryButton:pressed PathIcon">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Button#PART_SecondaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-primary-pressed /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
 
-  <!-- CheckedSecondaryPointerOver State -->
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPointerOver}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Button#PART_SecondaryButton">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPointerOver}" />
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pointerover /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPointerOver}" />
+  <!-- SplitButton Checked Pressed State -->
+  <Style Selector="SplitButton:pressed:checked /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:pressed:checked /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:pressed:checked /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:pressed:checked /template/ Button#PART_SecondaryButton PathIcon">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
 
-  <!-- CheckedSecondaryPressed State -->
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#RootBorder">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#PrimaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Border#SecondaryBackgroundBorder">
-    <Setter Property="Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Button#PART_PrimaryButton">
-    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundChecked}" />
-  </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Button#PART_SecondaryButton">
-    <Setter Property="BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+  <!-- Checked Flyout Open State -->
+  <Style Selector="SplitButton:checked:flyout-open /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:checked:flyout-open /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:checked:flyout-open /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundCheckedPressed}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedPressed}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
+  </Style>
+  <Style Selector="SplitButton:checked:flyout-open /template/ Button#PART_SecondaryButton PathIcon">
     <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
   </Style>
-  <Style Selector="SplitButton:checked-secondary-pressed /template/ Path#DropDownGlyphPath">
-    <Setter Property="Fill" Value="{DynamicResource SplitButtonForegroundCheckedPressed}" />
-  </Style>
 
-  <!-- SecondaryButtonPlacement States -->
-  <!-- Note: Setting Grid attached properties doesn't work here for some unknown reason.
-       They simply are never changed. In addition, touch-device changes of secondary button
-       size are currently disabled in code-behind. -->
-  <Style Selector="SplitButton:secondary-button-right /template/ Button#PART_SecondaryButton">
-    <Setter Property="(Grid.Column)" Value="2" />
-    <Setter Property="(Grid.ColumnSpan)" Value="1" />
+  <!-- Disabled Checked State -->
+  <Style Selector="SplitButton:checked:disabled /template/ Button#PART_PrimaryButton /template/ ContentPresenter,
+         SplitButton:checked:disabled /template/ Button#PART_SecondaryButton /template/ ContentPresenter,
+         SplitButton:checked:disabled /template/ Border#SeparatorBorder">
+    <Setter Property="Border.Background" Value="{DynamicResource SplitButtonBackgroundCheckedDisabled}" />
+    <Setter Property="Border.BorderBrush" Value="{DynamicResource SplitButtonBorderBrushCheckedDisabled}" />
+    <Setter Property="TextBlock.Foreground" Value="{DynamicResource SplitButtonForegroundCheckedDisabled}" />
   </Style>
-  <Style Selector="SplitButton:secondary-button-span /template/ Button#PART_SecondaryButton">
-    <Setter Property="(Grid.Column)" Value="0" />
-    <Setter Property="(Grid.ColumnSpan)" Value="3" />
+  <Style Selector="SplitButton:checked:disabled /template/ Button#PART_SecondaryButton PathIcon">
+    <Setter Property="Foreground" Value="{DynamicResource SplitButtonForegroundCheckedDisabled}" />
   </Style>
-
 </Styles>

From 7f00daeee29d9e65af7c7f462ced1ae80e90de15 Mon Sep 17 00:00:00 2001
From: robloo <robloo@users.noreply.github.com>
Date: Sat, 5 Feb 2022 00:45:01 -0500
Subject: [PATCH 46/48] Add Re-themed SplitButton example in ControlCatalog

---
 samples/ControlCatalog/Pages/ButtonsPage.xaml | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/samples/ControlCatalog/Pages/ButtonsPage.xaml b/samples/ControlCatalog/Pages/ButtonsPage.xaml
index e2d1010859..7de0872eae 100644
--- a/samples/ControlCatalog/Pages/ButtonsPage.xaml
+++ b/samples/ControlCatalog/Pages/ButtonsPage.xaml
@@ -83,6 +83,9 @@
                   <SolidColorBrush x:Key="ButtonBackground">DarkRed</SolidColorBrush>
                   <SolidColorBrush x:Key="ButtonBackgroundPointerOver">Red</SolidColorBrush>
                   <SolidColorBrush x:Key="ButtonBackgroundPressed">OrangeRed</SolidColorBrush>
+                  <SolidColorBrush x:Key="ButtonForeground">White</SolidColorBrush>
+                  <SolidColorBrush x:Key="ButtonForegroundPointerOver">Black</SolidColorBrush>
+                  <SolidColorBrush x:Key="ButtonForegroundPressed">Black</SolidColorBrush>
                 </Style.Resources>
               </Style>
             </Button.Styles>
@@ -165,6 +168,26 @@
                      Flyout="{StaticResource SharedMenuFlyout}">
           <TextBlock Text="Disabled" />
         </SplitButton>
+        <SplitButton Flyout="{StaticResource SharedMenuFlyout}"
+                     Content="Re-themed">
+          <SplitButton.Styles>
+            <Style>
+              <Style.Resources>
+                <x:Double x:Key="SplitButtonSeparatorWidth">1.5</x:Double>
+                <Thickness x:Key="SplitButtonBorderThemeThickness">2</Thickness>
+                <SolidColorBrush x:Key="SplitButtonBorderBrush">Red</SolidColorBrush>
+                <SolidColorBrush x:Key="SplitButtonBorderBrushPointerOver">Red</SolidColorBrush>
+                <SolidColorBrush x:Key="SplitButtonBorderBrushPressed">Red</SolidColorBrush>
+                <SolidColorBrush x:Key="SplitButtonBackground">DarkRed</SolidColorBrush>
+                <SolidColorBrush x:Key="SplitButtonBackgroundPointerOver">Red</SolidColorBrush>
+                <SolidColorBrush x:Key="SplitButtonBackgroundPressed">OrangeRed</SolidColorBrush>
+                <SolidColorBrush x:Key="SplitButtonForeground">White</SolidColorBrush>
+                <SolidColorBrush x:Key="SplitButtonForegroundPointerOver">Black</SolidColorBrush>
+                <SolidColorBrush x:Key="SplitButtonForegroundPressed">Black</SolidColorBrush>
+              </Style.Resources>
+            </Style>
+          </SplitButton.Styles>
+        </SplitButton>
       </StackPanel>
     </Border>
 

From 28430ddadf41d6fb0c5a9168b4c01505157417e5 Mon Sep 17 00:00:00 2001
From: Max Katz <maxkatz6@outlook.com>
Date: Tue, 8 Feb 2022 03:16:18 -0500
Subject: [PATCH 47/48] Fix Default theme

---
 .../Controls/SplitButton.xaml                 | 44 +++++++++----------
 1 file changed, 22 insertions(+), 22 deletions(-)

diff --git a/src/Avalonia.Themes.Default/Controls/SplitButton.xaml b/src/Avalonia.Themes.Default/Controls/SplitButton.xaml
index 21ce9b61b8..ec40898fbe 100644
--- a/src/Avalonia.Themes.Default/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Default/Controls/SplitButton.xaml
@@ -22,31 +22,31 @@
     <converters:MarginMultiplierConverter x:Key="SecondaryButtonBorderMultiplier" Right="True" Top="True" Bottom="True" Indent="1" />
     <converters:MarginMultiplierConverter x:Key="SeparatorBorderMultiplier" Top="True" Bottom="True" Indent="1" />
 
-    <StaticResource x:Key="SplitButtonBackground" ResourceKey="ThemeControlMidBrush" />
-    <StaticResource x:Key="SplitButtonBackgroundPointerOver" ResourceKey="ThemeControlMidBrush" />
-    <StaticResource x:Key="SplitButtonBackgroundPressed" ResourceKey="ThemeControlHighBrush" />
+    <SolidColorBrush x:Key="SplitButtonBackground" Color="{DynamicResource ThemeControlMidColor}" />
+    <SolidColorBrush x:Key="SplitButtonBackgroundPointerOver" Color="{DynamicResource ThemeControlMidColor}" />
+    <SolidColorBrush x:Key="SplitButtonBackgroundPressed" Color="{DynamicResource ThemeBorderHighColor}" />
     <SolidColorBrush x:Key="SplitButtonBackgroundDisabled" Color="{DynamicResource ThemeControlMidColor}" Opacity="{DynamicResource ThemeDisabledOpacity}" />
-    <StaticResource x:Key="SplitButtonBackgroundChecked" ResourceKey="ThemeControlHighBrush" />
-    <StaticResource x:Key="SplitButtonBackgroundCheckedPointerOver" ResourceKey="ThemeControlHighBrush" />
-    <StaticResource x:Key="SplitButtonBackgroundCheckedPressed" ResourceKey="ThemeControlHighBrush" />
+    <SolidColorBrush x:Key="SplitButtonBackgroundChecked" Color="{DynamicResource ThemeBorderHighColor}" />
+    <SolidColorBrush x:Key="SplitButtonBackgroundCheckedPointerOver" Color="{DynamicResource ThemeBorderHighColor}" />
+    <SolidColorBrush x:Key="SplitButtonBackgroundCheckedPressed" Color="{DynamicResource ThemeBorderHighColor}" />
     <SolidColorBrush x:Key="SplitButtonBackgroundCheckedDisabled" Color="{DynamicResource ThemeControlHighColor}" Opacity="{DynamicResource ThemeDisabledOpacity}" />
-    
-    <StaticResource x:Key="SplitButtonForeground" ResourceKey="ThemeForegroundBrush" />
-    <StaticResource x:Key="SplitButtonForegroundPointerOver" ResourceKey="ThemeForegroundBrush" />
-    <StaticResource x:Key="SplitButtonForegroundPressed" ResourceKey="ThemeForegroundBrush" />
-    <StaticResource x:Key="SplitButtonForegroundDisabled" ResourceKey="ThemeForegroundBrush" />
-    <StaticResource x:Key="SplitButtonForegroundChecked" ResourceKey="ThemeForegroundBrush" />
-    <StaticResource x:Key="SplitButtonForegroundCheckedPointerOver" ResourceKey="ThemeForegroundBrush" />
-    <StaticResource x:Key="SplitButtonForegroundCheckedPressed" ResourceKey="ThemeForegroundBrush" />
-    <StaticResource x:Key="SplitButtonForegroundCheckedDisabled" ResourceKey="ThemeForegroundBrush" />
 
-    <StaticResource x:Key="SplitButtonBorderBrush" ResourceKey="ThemeBorderLowBrush" />
-    <StaticResource x:Key="SplitButtonBorderBrushPointerOver" ResourceKey="ThemeBorderMidBrush" />
-    <StaticResource x:Key="SplitButtonBorderBrushPressed" ResourceKey="ThemeBorderLowBrush" />
-    <StaticResource x:Key="SplitButtonBorderBrushDisabled" ResourceKey="ThemeBorderLowBrush" />
-    <StaticResource x:Key="SplitButtonBorderBrushChecked" ResourceKey="ThemeBorderMidBrush" />
-    <StaticResource x:Key="SplitButtonBorderBrushCheckedPointerOver" ResourceKey="ThemeBorderMidBrush" />
-    <StaticResource x:Key="SplitButtonBorderBrushCheckedPressed" ResourceKey="ThemeControlHighBrush" />
+    <SolidColorBrush x:Key="SplitButtonForeground" Color="{DynamicResource ThemeForegroundColor}" />
+    <SolidColorBrush x:Key="SplitButtonForegroundPointerOver" Color="{DynamicResource ThemeForegroundColor}" />
+    <SolidColorBrush x:Key="SplitButtonForegroundPressed" Color="{DynamicResource ThemeForegroundColor}" />
+    <SolidColorBrush x:Key="SplitButtonForegroundDisabled" Color="{DynamicResource ThemeForegroundColor}" />
+    <SolidColorBrush x:Key="SplitButtonForegroundChecked" Color="{DynamicResource ThemeForegroundColor}" />
+    <SolidColorBrush x:Key="SplitButtonForegroundCheckedPointerOver" Color="{DynamicResource ThemeForegroundColor}" />
+    <SolidColorBrush x:Key="SplitButtonForegroundCheckedPressed" Color="{DynamicResource ThemeForegroundColor}" />
+    <SolidColorBrush x:Key="SplitButtonForegroundCheckedDisabled" Color="{DynamicResource ThemeForegroundColor}" />
+
+    <SolidColorBrush x:Key="SplitButtonBorderBrush" Color="{DynamicResource ThemeBorderLowColor}" />
+    <SolidColorBrush x:Key="SplitButtonBorderBrushPointerOver" Color="{DynamicResource ThemeBorderMidColor}" />
+    <SolidColorBrush x:Key="SplitButtonBorderBrushPressed" Color="{DynamicResource ThemeBorderLowColor}" />
+    <SolidColorBrush x:Key="SplitButtonBorderBrushDisabled" Color="{DynamicResource ThemeBorderLowColor}" />
+    <SolidColorBrush x:Key="SplitButtonBorderBrushChecked" Color="{DynamicResource ThemeBorderMidColor}" />
+    <SolidColorBrush x:Key="SplitButtonBorderBrushCheckedPointerOver" Color="{DynamicResource ThemeBorderMidColor}" />
+    <SolidColorBrush x:Key="SplitButtonBorderBrushCheckedPressed" Color="{DynamicResource ThemeControlHighColor}" />
     <SolidColorBrush x:Key="SplitButtonBorderBrushCheckedDisabled" Color="{DynamicResource ThemeControlMidColor}" Opacity="{DynamicResource ThemeDisabledOpacity}" />
   </Styles.Resources>
 

From ecc6ba7acff4aa0c4446fc7bd63ae09c27ecb24c Mon Sep 17 00:00:00 2001
From: Max Katz <maxkatz6@outlook.com>
Date: Tue, 8 Feb 2022 03:39:31 -0500
Subject: [PATCH 48/48] Add missed converters

---
 src/Avalonia.Themes.Default/Controls/SplitButton.xaml | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/Avalonia.Themes.Default/Controls/SplitButton.xaml b/src/Avalonia.Themes.Default/Controls/SplitButton.xaml
index ec40898fbe..ce20a1a165 100644
--- a/src/Avalonia.Themes.Default/Controls/SplitButton.xaml
+++ b/src/Avalonia.Themes.Default/Controls/SplitButton.xaml
@@ -21,6 +21,10 @@
     <converters:MarginMultiplierConverter x:Key="PrimaryButtonBorderMultiplier" Left="True" Top="True" Bottom="True" Indent="1" />
     <converters:MarginMultiplierConverter x:Key="SecondaryButtonBorderMultiplier" Right="True" Top="True" Bottom="True" Indent="1" />
     <converters:MarginMultiplierConverter x:Key="SeparatorBorderMultiplier" Top="True" Bottom="True" Indent="1" />
+    <converters:CornerRadiusFilterConverter x:Key="TopCornerRadiusFilterConverter" Filter="TopLeft, TopRight"/>
+    <converters:CornerRadiusFilterConverter x:Key="RightCornerRadiusFilterConverter" Filter="TopRight, BottomRight"/>
+    <converters:CornerRadiusFilterConverter x:Key="BottomCornerRadiusFilterConverter" Filter="BottomLeft, BottomRight"/>
+    <converters:CornerRadiusFilterConverter x:Key="LeftCornerRadiusFilterConverter" Filter="TopLeft, BottomLeft"/>
 
     <SolidColorBrush x:Key="SplitButtonBackground" Color="{DynamicResource ThemeControlMidColor}" />
     <SolidColorBrush x:Key="SplitButtonBackgroundPointerOver" Color="{DynamicResource ThemeControlMidColor}" />