Fix regression with cancel

MatterControlLib/ApplicationView/Config/RunningTasksConfig.cs

@@ -84,7 +84,6 @@ using Newtonsoft.Json.Linq;
 
 namespace MatterHackers.MatterControl
 {
-
 	public class RunningTasksConfig
 	{
 		public event EventHandler TasksChanged;

MatterControlLib/PartPreviewWindow/RunningTaskRow.cs

@@ -167,6 +167,8 @@ namespace MatterHackers.MatterControl.PartPreviewWindow
 				theme,
 				5);
 
+			stopButton.Enabled = true;
+
 			stopButton.Click += (s, e) =>
 			{
 				var stopAction = taskDetails.Options?.StopAction;

MatterControlLib/PartPreviewWindow/View3D/Actions/SubtractAndReplaceObject3D_2.cs

@@ -250,6 +250,13 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 
 					foreach (var paint in paintObjects)
 					{
+						if (cancellationToken.IsCancellationRequested)
+						{
+							SourceContainer.Visible = true;
+							RemoveAllButSource();
+							return;
+						}
+
 						Mesh paintMesh = BooleanProcessing.Do(keepResultsMesh,
 							keepWorldMatrix,
 							// paint data

Submodules/MatterSlice

@@ -1 +1 @@
-Subproject commit 30290ea1208ce3180527ded33b7022c7c8b983de
+Subproject commit d37d5586bf98be61039c28a085ccea2d69ab6fa2

Submodules/agg-sharp

@@ -1 +1 @@
-Subproject commit 5f4e2a3ed9aad84e6cfa2259eb418ab94d5f24e0
+Subproject commit 4f8dfe49e47e0cdf1e3d954edaa189f87b4adc49