From 3b11401558678a27d6c6f5103e58252de04761f0 Mon Sep 17 00:00:00 2001
From: juliuszint <julius.zint@awin-software.de>
Date: Mon, 26 Jun 2017 20:29:23 +0200
Subject: [PATCH] Unsubscribe from IDefinition.SizeChanged event when set via
 indexer (#1014)

* Unsubscribe from IDefinition.SizeChanged event when set via indexer

* added bounds and null check to preserve original exception

* index check for negative values
---
 Xamarin.Forms.Core/DefinitionCollection.cs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Xamarin.Forms.Core/DefinitionCollection.cs b/Xamarin.Forms.Core/DefinitionCollection.cs
index bf0e4d06f..6310a4212 100644
--- a/Xamarin.Forms.Core/DefinitionCollection.cs
+++ b/Xamarin.Forms.Core/DefinitionCollection.cs
@@ -83,6 +83,9 @@ namespace Xamarin.Forms
 			get { return _internalList[index]; }
 			set
 			{
+				if(index < _internalList.Count && _internalList[index] != null && index >= 0)
+					_internalList[index].SizeChanged -= OnItemSizeChanged;
+
 				_internalList[index] = value;
 				value.SizeChanged += OnItemSizeChanged;
 				OnItemSizeChanged(this, EventArgs.Empty);
@@ -106,4 +109,4 @@ namespace Xamarin.Forms
 				eh(this, EventArgs.Empty);
 		}
 	}
-}
\ No newline at end of file
+}