From e48fc5457c16cea2f7b60bc308f177b03a2c6ffb Mon Sep 17 00:00:00 2001
From: John Lewin <lewin76@gmail.com>
Date: Fri, 17 Jun 2016 11:13:55 -0700
Subject: [PATCH] Fix regression in preset selection

---
 SlicerConfiguration/Settings/SettingsProfile.cs | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/SlicerConfiguration/Settings/SettingsProfile.cs b/SlicerConfiguration/Settings/SettingsProfile.cs
index 9dba268c1..9a787bd4d 100644
--- a/SlicerConfiguration/Settings/SettingsProfile.cs
+++ b/SlicerConfiguration/Settings/SettingsProfile.cs
@@ -902,7 +902,16 @@ namespace MatterHackers.MatterControl.SlicerConfiguration
 		{
 			get
 			{
-				return ValueOrDefault("layer_id");
+				string layerKey = ValueOrDefault("layer_id");
+				if (string.IsNullOrEmpty(layerKey))
+				{
+					// Generate a new GUID when missing or empty. We can't do this in the constructor as the dictionary deserialization will fail if
+					// an existing key exists for layer_id and on new empty layers, we still need to construct an initial identifier. 
+					layerKey = Guid.NewGuid().ToString();
+					LayerID = layerKey;
+				}
+
+				return layerKey;
 			}
 			set
 			{