From 87ea75b3c11d797a65260c42bb60824a7547bc9b Mon Sep 17 00:00:00 2001
From: BDisp <bd.bdisp@gmail.com>
Date: Sun, 26 May 2024 17:23:19 +0100
Subject: [PATCH 1/3] v1 Fixes #2897. ListView ListWrapper - marking does work
 if you give an IList which in which the count changes

---
 Terminal.Gui/Views/ListView.cs | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/Terminal.Gui/Views/ListView.cs b/Terminal.Gui/Views/ListView.cs
index e0d4edbda..f340d7ebd 100644
--- a/Terminal.Gui/Views/ListView.cs
+++ b/Terminal.Gui/Views/ListView.cs
@@ -749,6 +749,11 @@ namespace Terminal.Gui {
 		public void EnsureSelectedItemVisible ()
 		{
 			SuperView?.LayoutSubviews ();
+			// If last item is selected and is removed, ensures a valid selected item
+			if (Source != null && selected > Source.Count - 1) {
+				SelectedItem = Source.Count - 1;
+				SetNeedsDisplay ();
+			}
 			if (selected < top) {
 				top = selected;
 			} else if (Frame.Height > 0 && selected >= top + Frame.Height) {
@@ -831,11 +836,30 @@ namespace Terminal.Gui {
 		}
 
 		/// <inheritdoc/>
-		public int Count => src != null ? src.Count : 0;
+		public int Count {
+			get {
+				CheckAndResizeMarksIfRequired ();
+				return src?.Count ?? 0;
+			}
+		}
 
 		/// <inheritdoc/>
 		public int Length => len;
 
+		void CheckAndResizeMarksIfRequired ()
+		{
+			if (count != src.Count) {
+				count = src.Count;
+				BitArray newMarks = new BitArray (count);
+				for (var i = 0; i < Math.Min (marks.Length, newMarks.Length); i++) {
+					newMarks [i] = marks [i];
+				}
+				marks = newMarks;
+
+				len = GetMaxLengthItem ();
+			}
+		}
+
 		int GetMaxLengthItem ()
 		{
 			if (src == null || src?.Count == 0) {
@@ -896,7 +920,7 @@ namespace Terminal.Gui {
 		/// <inheritdoc/>
 		public bool IsMarked (int item)
 		{
-			if (item >= 0 && item < count)
+			if (item >= 0 && item < Count)
 				return marks [item];
 			return false;
 		}
@@ -904,7 +928,7 @@ namespace Terminal.Gui {
 		/// <inheritdoc/>
 		public void SetMark (int item, bool value)
 		{
-			if (item >= 0 && item < count)
+			if (item >= 0 && item < Count)
 				marks [item] = value;
 		}
 

From d7b0899f2beffaeacba6bc28a642ac477f302155 Mon Sep 17 00:00:00 2001
From: BDisp <bd.bdisp@gmail.com>
Date: Sun, 26 May 2024 17:39:34 +0100
Subject: [PATCH 2/3] Prevent System.NullReferenceException.

---
 Terminal.Gui/Views/ListView.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Terminal.Gui/Views/ListView.cs b/Terminal.Gui/Views/ListView.cs
index f340d7ebd..0ef93d00e 100644
--- a/Terminal.Gui/Views/ListView.cs
+++ b/Terminal.Gui/Views/ListView.cs
@@ -848,7 +848,7 @@ namespace Terminal.Gui {
 
 		void CheckAndResizeMarksIfRequired ()
 		{
-			if (count != src.Count) {
+			if (src != null && count != src.Count) {
 				count = src.Count;
 				BitArray newMarks = new BitArray (count);
 				for (var i = 0; i < Math.Min (marks.Length, newMarks.Length); i++) {

From d5bf412d376fbfc89440ea24370c6a685fb18411 Mon Sep 17 00:00:00 2001
From: BDisp <bd.bdisp@gmail.com>
Date: Wed, 29 May 2024 12:34:59 +0100
Subject: [PATCH 3/3] Adjust the top considering the selected item and the
 frame height.

---
 Terminal.Gui/Views/ListView.cs   |  6 ++++--
 UnitTests/Views/ListViewTests.cs | 18 +++++++++---------
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/Terminal.Gui/Views/ListView.cs b/Terminal.Gui/Views/ListView.cs
index 0ef93d00e..ae6528d94 100644
--- a/Terminal.Gui/Views/ListView.cs
+++ b/Terminal.Gui/Views/ListView.cs
@@ -601,10 +601,12 @@ namespace Terminal.Gui {
 		/// <returns></returns>
 		public virtual bool MoveEnd ()
 		{
-			if (source.Count > 0 && selected != source.Count - 1) {
+			if (source?.Count > 0 && selected != source.Count - 1) {
 				selected = source.Count - 1;
 				if (top + selected > Frame.Height - 1) {
-					top = selected;
+					top = selected < Frame.Height - 1
+						? Math.Max (Frame.Height - selected + 1, 0)
+						: Math.Max (selected - Frame.Height + 1, 0);
 				}
 				OnSelectedChanged ();
 				SetNeedsDisplay ();
diff --git a/UnitTests/Views/ListViewTests.cs b/UnitTests/Views/ListViewTests.cs
index f705dab25..1f6589204 100644
--- a/UnitTests/Views/ListViewTests.cs
+++ b/UnitTests/Views/ListViewTests.cs
@@ -300,16 +300,16 @@ namespace Terminal.Gui.ViewTests {
 			Assert.Equal (19, lv.SelectedItem);
 			TestHelpers.AssertDriverContentsWithFrameAre (@"
 ┌──────────┐
+│Line10    │
+│Line11    │
+│Line12    │
+│Line13    │
+│Line14    │
+│Line15    │
+│Line16    │
+│Line17    │
+│Line18    │
 │Line19    │
-│          │
-│          │
-│          │
-│          │
-│          │
-│          │
-│          │
-│          │
-│          │
 └──────────┘", output);
 
 			Assert.True (lv.ScrollUp (20));