Port ListControlStringCollectionEditor

Closes #1271

src/System.Design/src/System.Design.Forwards.cs

@@ -1,12 +1,12 @@
 // Licensed to the .NET Foundation under one or more agreements.
-// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
 using System.Runtime.CompilerServices;
 
 [assembly: TypeForwardedTo(typeof(System.Windows.Forms.Design.ImageCollectionEditor))]
 [assembly: TypeForwardedTo(typeof(System.Windows.Forms.Design.ImageIndexEditor))]
+[assembly: TypeForwardedTo(typeof(System.Windows.Forms.Design.ListControlStringCollectionEditor))]
 [assembly: TypeForwardedTo(typeof(System.Windows.Forms.Design.StringArrayEditor))]
 [assembly: TypeForwardedTo(typeof(System.Windows.Forms.Design.StringCollectionEditor))]
 [assembly: TypeForwardedTo(typeof(System.Windows.Forms.Design.TabPageCollectionEditor))]

src/System.Windows.Forms.Design.Editors/src/Resources/SR.resx

@@ -148,6 +148,9 @@
   <data name="ColorEditorSystemTab" xml:space="preserve">
     <value>System</value>
   </data>
+  <data name="DataSourceLocksItems" xml:space="preserve">
+    <value>Items collection cannot be modified when the DataSource property is set.</value>
+  </data>
   <data name="DockEditorAccName" xml:space="preserve">
     <value>Dock Picker</value>
   </data>

src/System.Windows.Forms.Design.Editors/src/System/Windows/Forms/Design/ListControlStringCollectionEditor.cs

@@ -0,0 +1,32 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.ComponentModel;
+
+namespace System.Windows.Forms.Design
+{
+    /// <summary>
+    ///  The ListControlStringCollectionEditor override StringCollectionEditor
+    ///  to prevent the string collection from being edited if a DataSource
+    ///  has been set on the control.
+    /// </summary>
+    internal class ListControlStringCollectionEditor : StringCollectionEditor
+    {
+        public ListControlStringCollectionEditor(Type type) : base(type)
+        {
+        }
+
+        public override object EditValue(ITypeDescriptorContext context, IServiceProvider provider, object value)
+        {
+            // If we're trying to edit the items in an object that has a DataSource set, throw an exception
+            ListControl control = context.Instance as ListControl;
+            if (control?.DataSource != null)
+            {
+                throw new ArgumentException(SR.DataSourceLocksItems);
+            }
+
+            return base.EditValue(context, provider, value);
+        }
+    }
+}