Add MenuItemAttach.

src/Shared/HandyControl_Shared/Controls/Attach/MenuItemAttach.cs

@@ -0,0 +1,74 @@
+using System.Linq;
+using System.Windows;
+using System.Windows.Controls;
+
+namespace HandyControl.Controls
+{
+    public class MenuItemAttach
+    {
+        public static readonly DependencyProperty GroupNameProperty =
+            DependencyProperty.RegisterAttached("GroupName", typeof(string), typeof(MenuItemAttach),
+                                                new PropertyMetadata(string.Empty, GroupNamePropertyChanged));
+
+        [AttachedPropertyBrowsableForType(typeof(MenuItem))]
+        public static string GetGroupName(DependencyObject obj)
+        {
+            return (string) obj.GetValue(GroupNameProperty);
+        }
+
+        [AttachedPropertyBrowsableForType(typeof(MenuItem))]
+        public static void SetGroupName(DependencyObject obj, string value)
+        {
+            obj.SetValue(GroupNameProperty, value);
+        }
+
+        private static void GroupNamePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+        {
+            if (d is MenuItem menuItem)
+            {
+                var newGroupName = e.NewValue.ToString();
+                var oldGroupName = e.OldValue.ToString();
+
+                if (string.IsNullOrWhiteSpace(newGroupName))
+                {
+                    menuItem.Checked -= MenuItem_Checked;
+                    menuItem.Click -= MenuItem_Click;
+
+                }
+                else if (string.IsNullOrWhiteSpace(oldGroupName))
+                {
+                    // When the oldGroupName is null or white space,
+                    // it means we had removed the Checked event handler or never add, so we need add one.
+                    menuItem.Checked += MenuItem_Checked;
+
+                    // The same to Checked event.
+                    menuItem.Click += MenuItem_Click;
+                }
+            }
+        }
+
+        private static void MenuItem_Checked(object sender, RoutedEventArgs e)
+        {
+            if (sender is MenuItem menuItem && menuItem.Parent is MenuItem parent)
+            {
+                var groupName = GetGroupName(menuItem);
+
+                foreach (var item in parent.Items.OfType<MenuItem>().Where(m => m != menuItem &&
+                                                                                m.IsCheckable &&
+                                                                                GetGroupName(m) == groupName))
+                {
+                    item.IsChecked = false;
+                }
+            }
+        }
+
+        private static void MenuItem_Click(object sender, RoutedEventArgs e)
+        {
+            // prevent uncheck when click the checked menu item
+            if (e.OriginalSource is MenuItem menuItem && !menuItem.IsChecked)
+            {
+                menuItem.IsChecked = true;
+            }
+        }
+    }
+}

src/Shared/HandyControl_Shared/HandyControl_Shared.projitems

@@ -19,6 +19,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\IconSwitchElement.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\ImageAttach.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\InfoElement.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\MenuItemAttach.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\MenuTopLineAttach.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\PanelElement.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\PasswordBoxAttach.cs" />