From 759d6501a5e2785497e034125f1508e5deea8e07 Mon Sep 17 00:00:00 2001
From: Eberhard Beilharz <eb1@sil.org>
Date: Mon, 7 May 2012 17:53:22 +0200
Subject: [PATCH] Xamarin-4921: Fix Listbox.SelectedItem after adding sorted
 item

When we add an item to a sorted listbox the indices of the selected
items change and need to be updated.

Change-Id: Ia32849fe10480354835dcd48b37d326d612af04f
---
 .../System.Windows.Forms/ListBox.cs           | 15 +++++-
 .../Test/System.Windows.Forms/ListBoxTest.cs  | 53 +++++++++++++++++++
 2 files changed, 67 insertions(+), 1 deletion(-)

diff --git a/mcs/class/Managed.Windows.Forms/System.Windows.Forms/ListBox.cs b/mcs/class/Managed.Windows.Forms/System.Windows.Forms/ListBox.cs
index ad14ddaefbe..e91853f0fd7 100644
--- a/mcs/class/Managed.Windows.Forms/System.Windows.Forms/ListBox.cs
+++ b/mcs/class/Managed.Windows.Forms/System.Windows.Forms/ListBox.cs
@@ -2531,13 +2531,26 @@ namespace System.Windows.Forms
 			public int Add (object item)
 			{
 				int idx;
+				object[] selectedItems = null;
+
+				// we need to remember the original selected items so that we can update the indices
+				if (owner.sorted) {
+					selectedItems = new object[owner.SelectedItems.Count];
+					owner.SelectedItems.CopyTo (selectedItems, 0);
+				}
 
 				idx = AddItem (item);
 				owner.CollectionChanged ();
 				
 				// If we are sorted, the item probably moved indexes, get the real one
-				if (owner.sorted)
+				if (owner.sorted) {
+					// update indices of selected items
+					owner.SelectedIndices.Clear ();
+					for (int i = 0; i < selectedItems.Length; i++) {
+						owner.SelectedIndex = this.IndexOf (selectedItems [i]);
+					}
 					return this.IndexOf (item);
+				}
 					
 				return idx;
 			}
diff --git a/mcs/class/Managed.Windows.Forms/Test/System.Windows.Forms/ListBoxTest.cs b/mcs/class/Managed.Windows.Forms/Test/System.Windows.Forms/ListBoxTest.cs
index 3b2a6b950b4..c72999b8ac9 100644
--- a/mcs/class/Managed.Windows.Forms/Test/System.Windows.Forms/ListBoxTest.cs
+++ b/mcs/class/Managed.Windows.Forms/Test/System.Windows.Forms/ListBoxTest.cs
@@ -854,6 +854,59 @@ namespace MonoTests.System.Windows.Forms
 			}
 			Assert.AreEqual ((Array)expectedAddPositions, (Array)addedAtList.ToArray (typeof (int)), "addedAtList");
 		}
+
+		[Test]
+		public void SelectedIndexUpdated () // Xamarin bug 4921
+		{
+			using (Form f = new Form ()) {
+				f.ShowInTaskbar = false;
+
+				ListBox l = new ListBox ();
+				l.Sorted = true;
+				f.Controls.Add (l);
+
+				l.Items.Add ("B");
+				l.SelectedIndex = 0;
+
+				Assert.AreEqual (0, l.SelectedIndex);
+
+				l.Items.Add ("A");
+				Assert.AreEqual (1, l.SelectedIndex);
+			}
+		}
+
+		[Test]
+		public void SelectedIndexUpdated_MultiSelect () // Xamarin bug 4921
+		{
+			using (Form f = new Form ()) {
+				f.ShowInTaskbar = false;
+
+				ListBox l = new ListBox ();
+				l.Sorted = true;
+				l.SelectionMode = SelectionMode.MultiSimple;
+				f.Controls.Add (l);
+
+				l.Items.Add ("B");
+				l.Items.Add ("C");
+				l.SelectedIndex = 0;
+				l.SelectedIndex = 1;
+
+				Assert.AreEqual (2, l.SelectedIndices.Count);
+				Assert.AreEqual (0, l.SelectedIndices [0]);
+				Assert.AreEqual (1, l.SelectedIndices [1]);
+				Assert.AreEqual (2, l.SelectedItems.Count);
+				Assert.AreEqual ("B", l.SelectedItems [0]);
+				Assert.AreEqual ("C", l.SelectedItems [1]);
+
+				l.Items.Add ("A");
+				Assert.AreEqual (2, l.SelectedIndices.Count);
+				Assert.AreEqual (1, l.SelectedIndices[0]);
+				Assert.AreEqual (2, l.SelectedIndices[1]);
+				Assert.AreEqual (2, l.SelectedItems.Count);
+				Assert.AreEqual ("B", l.SelectedItems [0]);
+				Assert.AreEqual ("C", l.SelectedItems [1]);
+			}
+		}
 	}
 
 	[TestFixture]
-- 
2.25.1