enhance: add ListBoxAttach.

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

@@ -0,0 +1,66 @@
+using System.Collections;
+using System.Linq;
+using System.Windows;
+using System.Windows.Controls;
+using HandyControl.Data;
+
+namespace HandyControl.Controls;
+
+public class ListBoxAttach
+{
+    public static readonly DependencyProperty SelectedItemsProperty = DependencyProperty.RegisterAttached(
+        "SelectedItems", typeof(IList), typeof(ListBoxAttach),
+        new FrameworkPropertyMetadata(default(IList), FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
+            OnSelectedItemsChanged));
+
+    public static void SetSelectedItems(DependencyObject element, IList value)
+        => element.SetValue(SelectedItemsProperty, value);
+
+    public static IList GetSelectedItems(DependencyObject element)
+        => (IList) element.GetValue(SelectedItemsProperty);
+
+    internal static readonly DependencyProperty InternalActionProperty = DependencyProperty.RegisterAttached(
+        "InternalAction", typeof(bool), typeof(ListBoxAttach), new PropertyMetadata(ValueBoxes.FalseBox));
+
+    internal static void SetInternalAction(DependencyObject element, bool value)
+        => element.SetValue(InternalActionProperty, ValueBoxes.BooleanBox(value));
+
+    internal static bool GetInternalAction(DependencyObject element)
+        => (bool) element.GetValue(InternalActionProperty);
+
+    private static void OnSelectedItemsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+    {
+        if (d is not ListBox listBox)
+        {
+            return;
+        }
+
+        if (GetInternalAction(listBox))
+        {
+            return;
+        }
+
+        listBox.SelectionChanged -= OnListBoxSelectionChanged;
+        listBox.SelectedItems.Clear();
+
+        if (e.NewValue is IList selectedItems)
+        {
+            foreach (object selectedItem in selectedItems)
+            {
+                listBox.SelectedItems.Add(selectedItem);
+            }
+        }
+
+        listBox.SelectionChanged += OnListBoxSelectionChanged;
+    }
+
+    private static void OnListBoxSelectionChanged(object sender, SelectionChangedEventArgs e)
+    {
+        if (sender is ListBox listBox)
+        {
+            SetInternalAction(listBox, true);
+            SetSelectedItems(listBox, listBox.SelectedItems.Cast<object>().ToArray());
+            SetInternalAction(listBox, false);
+        }
+    }
+}

src/Shared/HandyControl_Shared/HandyControl_Shared.projitems

@@ -21,6 +21,7 @@
     <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\ListBoxAttach.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\MenuAttach.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\MenuTopLineAttach.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Controls\Attach\PanelElement.cs" />