diff --git a/PartPreviewWindow/View3D/View3DWidget.cs b/PartPreviewWindow/View3D/View3DWidget.cs
index 695f9b8f1..40b80e790 100644
--- a/PartPreviewWindow/View3D/View3DWidget.cs
+++ b/PartPreviewWindow/View3D/View3DWidget.cs
@@ -570,6 +570,9 @@ namespace MatterHackers.MatterControl.PartPreviewWindow
 				BeforeDraw += CreateBooleanTestGeometry;
 				AfterDraw += RemoveBooleanTestGeometry;
 			}
+
+			AfterDraw += AfterDebugTest;
+
 			meshViewerWidget.TrackballTumbleWidget.DrawGlContent += TrackballTumbleWidget_DrawGlContent;
 		}
 
@@ -1083,6 +1086,25 @@ namespace MatterHackers.MatterControl.PartPreviewWindow
 			base.OnDraw(graphics2D);
 		}
 
+		private void AfterDebugTest(object sender, DrawEventArgs e)
+		{
+			foreach (var bvhAndTransform in Scene?.TraceData().MakeEnumerable())
+			{
+				TriangleShape tri = bvhAndTransform.Bvh as TriangleShape;
+				if (tri != null)
+				{
+					for (int i = 0; i < 3; i++)
+					{
+						var vertexPos = tri.GetVertex(i);
+						var screenCenter = Vector3.Transform(vertexPos, bvhAndTransform.TransformToWorld);
+						var screenPos = meshViewerWidget.TrackballTumbleWidget.GetScreenPosition(screenCenter);
+
+						e.graphics2D.Circle(screenPos, 3, RGBA_Bytes.Red);
+					}
+				}
+			}
+		}
+
 		private ViewControls3DButtons? activeButtonBeforeMouseOverride = null;
 		private ViewControls3DButtons? activeButtonBeforeKeyOverride = null;
 
diff --git a/PartPreviewWindow/ViewGcodeBasic.cs b/PartPreviewWindow/ViewGcodeBasic.cs
index 611743542..4f86f6b36 100644
--- a/PartPreviewWindow/ViewGcodeBasic.cs
+++ b/PartPreviewWindow/ViewGcodeBasic.cs
@@ -329,11 +329,11 @@ namespace MatterHackers.MatterControl.PartPreviewWindow
 				switch (e.TransformMode)
 				{
 					case ViewControls3DButtons.Translate:
-						gcodeViewWidget.TransformState = ViewGcodeWidget.ETransformState.Move;
+						if(gcodeViewWidget != null) gcodeViewWidget.TransformState = ViewGcodeWidget.ETransformState.Move;
 						meshViewerWidget.TrackballTumbleWidget.TransformState = TrackBallController.MouseDownType.Translation;
 						break;
 					case ViewControls3DButtons.Scale:
-						gcodeViewWidget.TransformState = ViewGcodeWidget.ETransformState.Scale;
+						if (gcodeViewWidget != null) gcodeViewWidget.TransformState = ViewGcodeWidget.ETransformState.Scale;
 						meshViewerWidget.TrackballTumbleWidget.TransformState = TrackBallController.MouseDownType.Scale;
 						break;
 					case ViewControls3DButtons.Rotate:
diff --git a/Submodules/agg-sharp b/Submodules/agg-sharp
index 4065cbd70..f371813bc 160000
--- a/Submodules/agg-sharp
+++ b/Submodules/agg-sharp
@@ -1 +1 @@
-Subproject commit 4065cbd70e13f9abb26610b82eb8038fa3cf6efb
+Subproject commit f371813bcf25ddeac939075974558f656ec6cb01