8768 :: Resolve Addrange issue after sorting. (#11423)

* 8768 :: Resolve Addrange issue after sorting.

src/System.Windows.Forms.Primitives/src/System/LocalAppContextSwitches/LocalAppContextSwitches.cs

@@ -24,6 +24,7 @@ internal static partial class LocalAppContextSwitches
     internal const string DataGridViewUIAStartRowCountAtZeroSwitchName = "System.Windows.Forms.DataGridViewUIAStartRowCountAtZero";
     internal const string NoClientNotificationsSwitchName = "Switch.System.Windows.Forms.AccessibleObject.NoClientNotifications";
     internal const string EnableMsoComponentManagerSwitchName = "Switch.System.Windows.Forms.EnableMsoComponentManager";
+    internal const string TreeNodeCollectionAddRangeRespectsSortOrderSwitchName = "System.Windows.Forms.TreeNodeCollectionAddRangeRespectsSortOrder";
 
     private static int s_scaleTopLevelFormMinMaxSizeForDpi;
     private static int s_anchorLayoutV2;
@@ -34,6 +35,7 @@ internal static partial class LocalAppContextSwitches
     private static int s_dataGridViewUIAStartRowCountAtZero;
     private static int s_noClientNotifications;
     private static int s_enableMsoComponentManager;
+    private static int s_treeNodeCollectionAddRangeRespectsSortOrder;
 
     private static FrameworkName? s_targetFrameworkName;
 
@@ -104,6 +106,11 @@ internal static partial class LocalAppContextSwitches
                 return false;
             }
 
+            if (switchName == TreeNodeCollectionAddRangeRespectsSortOrderSwitchName)
+            {
+                return true;
+            }
+
             if (framework.Version.Major >= 8)
             {
                 // Behavior changes added in .NET 8
@@ -202,6 +209,16 @@ internal static partial class LocalAppContextSwitches
         get => GetCachedSwitchValue(EnableMsoComponentManagerSwitchName, ref s_enableMsoComponentManager);
     }
 
+    /// <summary>
+    ///  When set to (default), API will insert nodes in the sorted order.
+    ///  To get behavior compatible with the previous versions of .NET and .NET Framework, set this switch to.
+    /// </summary>
+    public static bool TreeNodeCollectionAddRangeRespectsSortOrder
+    {
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        get => GetCachedSwitchValue(TreeNodeCollectionAddRangeRespectsSortOrderSwitchName, ref s_treeNodeCollectionAddRangeRespectsSortOrder);
+    }
+
     internal static void SetLocalAppContextSwitchValue(string switchName, bool value)
     {
         if (switchName == NoClientNotificationsSwitchName)
@@ -218,6 +235,11 @@ internal static partial class LocalAppContextSwitches
         {
             s_applyParentFontToMenus = value ? 1 : 0;
         }
+
+        if (switchName == TreeNodeCollectionAddRangeRespectsSortOrderSwitchName)
+        {
+            s_treeNodeCollectionAddRangeRespectsSortOrder = value ? 1 : 0;
+        }
     }
 
     internal static bool GetCachedSwitchValue(string switchName)

src/System.Windows.Forms/src/System/Windows/Forms/Controls/TreeView/TreeNodeCollection.cs

@@ -4,6 +4,7 @@
 using System.Collections;
 using System.ComponentModel;
 using System.Drawing.Design;
+using System.Windows.Forms.Primitives;
 
 namespace System.Windows.Forms;
 
@@ -219,7 +220,11 @@ public class TreeNodeCollection : IList
             tv.BeginUpdate();
         }
 
-        _owner.Nodes.FixedIndex = _owner._childCount;
+        if (!LocalAppContextSwitches.TreeNodeCollectionAddRangeRespectsSortOrder || tv is null || !tv.Sorted)
+        {
+            _owner.Nodes.FixedIndex = _owner._childCount;
+        }
+
         _owner.EnsureCapacity(nodes.Length);
         for (int i = nodes.Length - 1; i >= 0; i--)
         {

src/System.Windows.Forms/tests/UnitTests/System/Windows/Forms/TreeNodeCollectionTests.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Drawing;
+using System.Windows.Forms.Primitives;
 
 namespace System.Windows.Forms.Tests;
 
@@ -214,6 +215,119 @@ public class TreeNodeCollectionTests
         Assert.Empty(collection.Find(key, searchAllChildren: false));
     }
 
+    [WinFormsFact]
+    public void TreeNodeCollection_Sort_ShouldAfterAddingItems()
+    {
+        using TreeView treeView = new();
+        string key = "7";
+        TreeNode child1 = new()
+        {
+            Name = "8",
+            Text = "8"
+        };
+        TreeNode child2 = new()
+        {
+            Name = "5",
+            Text = "5"
+        };
+        TreeNode child3 = new()
+        {
+            Name = "7",
+            Text = "7"
+        };
+
+        treeView.Nodes.Add(child1);
+        treeView.Nodes.Add(child2);
+        treeView.Nodes.Add(child3);
+
+        treeView.Sort();
+        treeView.CreateControl();
+
+        TreeNode[] treeNodeArray = new TreeNode[]
+        {
+            new()
+            {
+                Name = "2",
+                Text = "2"
+            },
+            new()
+            {
+                Name = "1",
+                Text = "1"
+            }
+        };
+
+        treeView.Nodes.AddRange(treeNodeArray);
+
+        TreeNode treeNode = treeView.Nodes.Find(key, searchAllChildren: true)[0];
+        treeNode.Should().NotBeNull();
+        treeView.Nodes.IndexOf(treeNode).Should().Be(3);
+    }
+
+    [WinFormsFact]
+    public void TreeNodeCollection_TreeNodeCollectionAddRangeRespectsSortOrderSwitch()
+    {
+        TreeNode child1 = new()
+        {
+            Name = "8",
+            Text = "8"
+        };
+        TreeNode child2 = new()
+        {
+            Name = "5",
+            Text = "5"
+        };
+        TreeNode child3 = new()
+        {
+            Name = "7",
+            Text = "7"
+        };
+        TreeNode[] treeNodeArray = new TreeNode[]
+        {
+            new()
+            {
+                Name = "2",
+                Text = "2"
+            },
+            new()
+            {
+                Name = "1",
+                Text = "1"
+            }
+        };
+
+        LocalAppContextSwitches.SetLocalAppContextSwitchValue(LocalAppContextSwitches.TreeNodeCollectionAddRangeRespectsSortOrderSwitchName, true);
+        using TreeView treeView2 = new();
+
+        treeView2.Nodes.Add(child1);
+        treeView2.Nodes.Add(child2);
+        treeView2.Nodes.Add(child3);
+
+        treeView2.CreateControl();
+        treeView2.Sort();
+        treeView2.Nodes.AddRange(treeNodeArray);
+
+        TreeNode treeNode = treeView2.Nodes.Find("2", searchAllChildren: true)[0];
+        treeNode.Should().NotBeNull();
+        treeView2.Nodes.IndexOf(treeNode).Should().Be(1);
+        treeView2.Nodes.Clear();
+
+        LocalAppContextSwitches.SetLocalAppContextSwitchValue(LocalAppContextSwitches.TreeNodeCollectionAddRangeRespectsSortOrderSwitchName, false);
+        using TreeView treeView3 = new();
+
+        treeView3.Nodes.Add(child1);
+        treeView3.Nodes.Add(child2);
+        treeView3.Nodes.Add(child3);
+
+        treeView3.CreateControl();
+        treeView3.Sort();
+        treeView3.Nodes.AddRange(treeNodeArray);
+
+        treeNode = treeView3.Nodes.Find("2", searchAllChildren: true)[0];
+        treeNode.Should().NotBeNull();
+        treeView3.Nodes.IndexOf(treeNode).Should().Be(1);
+    }
+
     [WinFormsTheory]
     [NullAndEmptyStringData]
     public void TreeNodeCollection_Find_NullOrEmptyKey_ThrowsArgumentNullException(string key)