Port TabPageCollectionEditor

Closes #1281

Author: Zachary Danz

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

@@ -9,3 +9,4 @@
 [assembly: TypeForwardedTo(typeof(System.Windows.Forms.Design.ImageIndexEditor))]
 [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/System/Windows/Forms/Design/TabPageCollectionEditor.cs

@@ -0,0 +1,45 @@
+// 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.Design;
+using System.Diagnostics;
+
+namespace System.Windows.Forms.Design
+{
+    /// <summary>
+    ///  Main class for collection editor for <see cref="TabControl.TabPageCollection"/>.
+    ///  Allows a single level of <see cref="ToolStripItem"/> children to be designed.
+    /// </summary>
+    internal class TabPageCollectionEditor : CollectionEditor
+    {
+        public TabPageCollectionEditor() : base(typeof(TabControl.TabPageCollection))
+        {
+        }
+
+        /// <summary>
+        ///  Sets the specified collection to have the specified array of items.
+        /// </summary>
+        protected override object SetItems(object editValue, object[] value)
+        {
+            var tabControl = Context.Instance as TabControl;
+            tabControl?.SuspendLayout();
+
+            object retValue = base.SetItems(editValue, value);
+
+            tabControl?.ResumeLayout();
+            return retValue;
+        }
+
+        protected override object CreateInstance(Type itemType)
+        {
+            object instance = base.CreateInstance(itemType);
+
+            TabPage tabPage = instance as TabPage;
+            Debug.Assert(tabPage != null);
+            tabPage.UseVisualStyleBackColor = true;
+
+            return tabPage;
+        }
+    }
+}

src/System.Windows.Forms.Design.Editors/tests/UnitTests/EnsureEditorsTests.cs

@@ -1,4 +1,4 @@
-// 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.
 
@@ -96,7 +96,7 @@ public void EnsureUITypeEditorForType(Type type, Type expectedEditorType)
         //[InlineData(typeof(MaskedTextBox), "Text", typeof(MaskedTextBoxTextEditor))]
         [InlineData(typeof(NotifyIcon), "BalloonTipText", typeof(MultilineStringEditor))]
         [InlineData(typeof(NotifyIcon), "Text", typeof(MultilineStringEditor))]
-        //[InlineData(typeof(TabControl), "TabPages", typeof(TabPageCollectionEditor))]
+        [InlineData(typeof(TabControl), "TabPages", typeof(TabPageCollectionEditor))]
         [InlineData(typeof(TabPage), "ImageIndex", typeof(ImageIndexEditor))]
         [InlineData(typeof(TabPage), "ImageKey", typeof(ImageIndexEditor))]
         //[InlineData(typeof(TextBox), "AutoCompleteCustomSource", typeof(ListControlStringCollectionEditor))]