From 1e1cf680702c4fc4d478f47a082ff3a7f525a609 Mon Sep 17 00:00:00 2001
From: John Lewin <lewin76@gmail.com>
Date: Thu, 13 Jul 2017 15:35:05 -0700
Subject: [PATCH] Guard for null reference

---
 PartPreviewWindow/PrinterTabPage.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/PartPreviewWindow/PrinterTabPage.cs b/PartPreviewWindow/PrinterTabPage.cs
index 0f6938276..ad16e8a90 100644
--- a/PartPreviewWindow/PrinterTabPage.cs
+++ b/PartPreviewWindow/PrinterTabPage.cs
@@ -115,7 +115,7 @@ namespace MatterHackers.MatterControl.PartPreviewWindow
 
 			viewControls3D.ResetView += (sender, e) =>
 			{
-				if (gcode2DWidget.Visible)
+				if (gcode2DWidget?.Visible == true)
 				{
 					gcode2DWidget.CenterPartInView();
 				}