From 321f6d75a87ccf42055582ce932a5c69bb06e652 Mon Sep 17 00:00:00 2001
From: xLEGiON <57880409+xLEGiON@users.noreply.github.com>
Date: Mon, 26 Feb 2024 14:14:10 +0000
Subject: [PATCH] Fix TreeDataGridPresenterBase Replace Regression

---
 .../Primitives/TreeDataGridPresenterBase.cs            | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/Avalonia.Controls.TreeDataGrid/Primitives/TreeDataGridPresenterBase.cs b/src/Avalonia.Controls.TreeDataGrid/Primitives/TreeDataGridPresenterBase.cs
index 4d133190..2350967d 100644
--- a/src/Avalonia.Controls.TreeDataGrid/Primitives/TreeDataGridPresenterBase.cs
+++ b/src/Avalonia.Controls.TreeDataGrid/Primitives/TreeDataGridPresenterBase.cs
@@ -705,7 +705,15 @@ private void OnItemsCollectionChanged(object? sender, NotifyCollectionChangedEve
                     _realizedElements.ItemsRemoved(e.OldStartingIndex, e.OldItems!.Count, _updateElementIndex, _recycleElementOnItemRemoved);
                     break;
                 case NotifyCollectionChangedAction.Replace:
-                    _realizedElements.ItemsReplaced(e.OldStartingIndex, e.OldItems!.Count, _recycleElementOnItemRemoved);
+                    if (e.OldItems!.Count == e.NewItems!.Count)
+                    {
+                        _realizedElements.ItemsReplaced(e.OldStartingIndex, e.OldItems!.Count, _recycleElementOnItemRemoved);
+                    }
+                    else
+                    {
+                        _realizedElements.ItemsRemoved(e.OldStartingIndex, e.OldItems!.Count, _updateElementIndex, _recycleElementOnItemRemoved);
+                        _realizedElements.ItemsInserted(e.NewStartingIndex, e.NewItems!.Count, _updateElementIndex);
+                    }
                     break;
                 case NotifyCollectionChangedAction.Move:
                     _realizedElements.ItemsRemoved(e.OldStartingIndex, e.OldItems!.Count, _updateElementIndex, _recycleElementOnItemRemoved);