Use `SetCurrentValue` for all `IMenuItem` properties (#20682)

* Add IMenuItem binding tests

* Use SetCurrentValue for all IMenuItem properties
Fix XMLDoc comments for MenuItem being inherited from an internal type

src/Avalonia.Controls/IMenuItem.cs

@@ -1,15 +1,11 @@
-using Avalonia.Metadata;
-
-namespace Avalonia.Controls
+namespace Avalonia.Controls
 {
     /// <summary>
     /// Represents a <see cref="MenuItem"/>.
     /// </summary>
     internal interface IMenuItem : IMenuElement
     {
-        /// <summary>
-        /// Gets or sets a value that indicates whether the item has a submenu.
-        /// </summary>
+        /// <inheritdoc cref="MenuItem.HasSubMenu"/>
         bool HasSubMenu { get; }
 
         /// <summary>
@@ -17,21 +13,13 @@ namespace Avalonia.Controls
         /// </summary>
         bool IsPointerOverSubMenu { get; }
 
-        /// <summary>
-        /// Gets or sets a value that indicates whether the submenu of the <see cref="MenuItem"/> is
-        /// open.
-        /// </summary>
+        /// <inheritdoc cref="MenuItem.IsSubMenuOpen"/>
         bool IsSubMenuOpen { get; set; }
 
-        /// <summary>
-        /// Gets or sets a value that indicates the submenu that this <see cref="MenuItem"/> is
-        /// within should not close when this item is clicked.
-        /// </summary>
+        /// <inheritdoc cref="MenuItem.StaysOpenOnClick"/>
         bool StaysOpenOnClick { get; set; }
 
-        /// <summary>
-        /// Gets a value that indicates whether the <see cref="MenuItem"/> is a top-level main menu item.
-        /// </summary>
+        /// <inheritdoc cref="MenuItem.IsTopLevel"/>
         bool IsTopLevel { get; }
 
         /// <summary>
@@ -39,20 +27,13 @@ namespace Avalonia.Controls
         /// </summary>
         IMenuElement? Parent { get; }
 
-        /// <summary>
-        /// Gets toggle type of the menu item.
-        /// </summary>
+        /// <inheritdoc cref="MenuItem.ToggleType"/>
         MenuItemToggleType ToggleType { get; }
 
-        /// <summary>
-        /// Gets menu item group name when <see cref="ToggleType"/> is <see cref="MenuItemToggleType.Radio"/>.
-        /// </summary>
+        /// <inheritdoc cref="MenuItem.GroupName"/>
         string? GroupName { get; }
 
-        /// <summary>
-        /// Gets or sets if menu item is checked when <see cref="ToggleType"/> is
-        /// <see cref="MenuItemToggleType.CheckBox"/> or <see cref="MenuItemToggleType.Radio"/>.
-        /// </summary>
+        /// <inheritdoc cref="MenuItem.IsChecked"/>
         bool IsChecked { get; set; }
 
         /// <summary>

src/Avalonia.Controls/MenuItem.cs

@@ -288,6 +288,12 @@ namespace Avalonia.Controls
             set => SetValue(IsSubMenuOpenProperty, value);
         }
 
+        bool IMenuItem.IsSubMenuOpen
+        {
+            get => IsSubMenuOpen;
+            set => SetCurrentValue(IsSubMenuOpenProperty, value);
+        }
+
         /// <summary>
         /// Gets or sets a value that indicates the submenu that this <see cref="MenuItem"/> is
         /// within should not close when this item is clicked.
@@ -298,27 +304,46 @@ namespace Avalonia.Controls
             set => SetValue(StaysOpenOnClickProperty, value);
         }
 
-        /// <inheritdoc cref="IMenuItem.ToggleType" />
+        bool IMenuItem.StaysOpenOnClick
+        {
+            get => StaysOpenOnClick; 
+            set => SetCurrentValue(StaysOpenOnClickProperty, value);
+        }
+
+        /// <summary>
+        /// Gets toggle type of the menu item.
+        /// </summary>
         public MenuItemToggleType ToggleType
         {
             get => GetValue(ToggleTypeProperty);
             set => SetValue(ToggleTypeProperty, value);
         }
 
-        /// <inheritdoc cref="IMenuItem.IsChecked"/>
+        /// <summary>
+        /// Gets or sets if menu item is checked when <see cref="ToggleType"/> is
+        /// <see cref="MenuItemToggleType.CheckBox"/> or <see cref="MenuItemToggleType.Radio"/>.
+        /// </summary>
         public bool IsChecked
         {
             get => GetValue(IsCheckedProperty);
             set => SetValue(IsCheckedProperty, value);
         }
 
+        bool IMenuItem.IsChecked
+        {
+            get => IsChecked;
+            set => SetCurrentValue(IsCheckedProperty, value);
+        }
+
         bool IRadioButton.IsChecked
         {
             get => IsChecked;
             set => SetCurrentValue(IsCheckedProperty, value);
         }
 
-        /// <inheritdoc cref="IMenuItem.GroupName"/>
+        /// <summary>
+        /// Gets menu item group name when <see cref="ToggleType"/> is <see cref="MenuItemToggleType.Radio"/>.
+        /// </summary>
         public string? GroupName
         {
             get => GetValue(GroupNameProperty);

tests/Avalonia.Controls.UnitTests/Platform/DefaultMenuInteractionHandlerTests.cs

@@ -1,6 +1,9 @@
 using System;
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
 using Avalonia.Controls.Platform;
 using Avalonia.Controls.Primitives;
+using Avalonia.Data;
 using Avalonia.Input;
 using Avalonia.Interactivity;
 using Avalonia.UnitTests;
@@ -224,6 +227,63 @@ namespace Avalonia.Controls.UnitTests.Platform
 
                 target.KeyDown(menu, e);
             }
+
+            private class MenuItemVM : INotifyPropertyChanged
+            {
+                public bool IsChecked { get; set { field = value; OnPropertyChanged(); } }
+                public bool IsSubMenuOpen { get; set { field = value; OnPropertyChanged(); } }
+
+                public event PropertyChangedEventHandler? PropertyChanged;
+
+                protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = "") => PropertyChanged?.Invoke(this, new(propertyName));
+            }
+
+            [Fact]
+            public void Doesnt_Replace_IsChecked_Binding()
+            {
+                var target = new DefaultMenuInteractionHandler(false);
+                var menu = new Menu();
+                var vm = new MenuItemVM();
+
+                var item = new MenuItem
+                {
+                    DataContext = vm,
+                    [!MenuItem.IsCheckedProperty] = new Binding(nameof(MenuItemVM.IsChecked)) { Priority = BindingPriority.Style, Mode = BindingMode.TwoWay },
+                    ToggleType = MenuItemToggleType.CheckBox,
+                };
+                menu.Items.Add(item);
+
+                target.KeyDown(item, new KeyEventArgs { Key = Key.Enter, Source = menu });
+
+                Assert.True(item.IsChecked);
+
+                vm.IsChecked = false;
+
+                Assert.False(item.IsChecked);
+            }
+
+            [Fact]
+            public void Doesnt_Replace_IsSubMenuOpen_Binding()
+            {
+                var target = new DefaultMenuInteractionHandler(false);
+                var menu = new Menu();
+                var vm = new MenuItemVM();
+
+                var item = new MenuItem
+                {
+                    DataContext = vm,
+                    [!MenuItem.IsSubMenuOpenProperty] = new Binding(nameof(MenuItemVM.IsSubMenuOpen)) { Priority = BindingPriority.Style, Mode = BindingMode.TwoWay },
+                    Items = { new MenuItem() }
+                };
+
+                target.KeyDown(item, new KeyEventArgs { Key = Key.Enter, Source = menu });
+
+                Assert.True(item.IsSubMenuOpen);
+
+                vm.IsSubMenuOpen = false;
+
+                Assert.False(item.IsSubMenuOpen);
+            }
         }
 
         public class NonTopLevel : ScopedTestBase