Adding ability to cancel rebuilding

MatterControlLib/ApplicationView/ApplicationController.cs

@@ -2171,14 +2171,14 @@ namespace MatterHackers.MatterControl
 
 			printer.ViewState.SlicingItem = true;
 
-			await this.Tasks.Execute("Slicing".Localize(), printer, async (reporter, cancellationToken) =>
+			await this.Tasks.Execute("Slicing".Localize(), printer, async (reporter, cancellationTokenSource) =>
 			{
 				slicingSucceeded = await Slicer.SliceItem(
 					object3D,
 					gcodeFilePath,
 					printer,
 					reporter,
-					cancellationToken);
+					cancellationTokenSource.Token);
 			});
 
 			printer.ViewState.SlicingItem = false;
@@ -2217,13 +2217,13 @@ namespace MatterHackers.MatterControl
 				}
 			}
 
-			await this.Tasks.Execute("Loading GCode".Localize(), printer, (innerProgress, token) =>
+			await this.Tasks.Execute("Loading GCode".Localize(), printer, (innerProgress, concelationTokenSource) =>
 			{
 				var status = new ProgressStatus();
 
 				innerProgress.Report(status);
 
-				printer.Bed.LoadActiveSceneGCode(gcodeFilePath, token, (progress0to1, statusText) =>
+				printer.Bed.LoadActiveSceneGCode(gcodeFilePath, concelationTokenSource.Token, (progress0to1, statusText) =>
 				{
 					UiThread.RunOnIdle(() =>
 					{
@@ -2434,7 +2434,7 @@ namespace MatterHackers.MatterControl
 
 			public int Priority { get; set; }
 
-			public Func<IProgress<ProgressStatus>, CancellationToken, Task> Action { get; set; }
+			public Func<IProgress<ProgressStatus>, CancellationTokenSource, Task> Action { get; set; }
 		}
 
 		public class StartupAction

MatterControlLib/ApplicationView/Config/BedConfig.cs

@@ -159,12 +159,12 @@ namespace MatterHackers.MatterControl
 
 		public async Task LoadGCodeContent(Stream stream)
 		{
-			await ApplicationController.Instance.Tasks.Execute("Loading G-Code".Localize(), Printer, (reporter, cancellationToken) =>
+			await ApplicationController.Instance.Tasks.Execute("Loading G-Code".Localize(), Printer, (reporter, cancellationTokenSource) =>
 			{
 				var progressStatus = new ProgressStatus();
 				reporter.Report(progressStatus);
 
-				this.LoadGCode(stream, cancellationToken, (progress0To1, status) =>
+				this.LoadGCode(stream, cancellationTokenSource.Token, (progress0To1, status) =>
 				{
 					progressStatus.Status = status;
 					progressStatus.Progress0To1 = progress0To1;
@@ -330,7 +330,7 @@ namespace MatterHackers.MatterControl
 			await insertionGroup.LoadingItemsTask;
 
 			// Persist changes
-			await this.SaveChanges(null, CancellationToken.None);
+			await this.SaveChanges(null, null);
 
 			// Slice and print
 			await ApplicationController.Instance.PrintPart(
@@ -650,9 +650,9 @@ namespace MatterHackers.MatterControl
 		/// Persists modified meshes to assets and saves pending changes back to the EditContext
 		/// </summary>
 		/// <param name="progress">Allows for progress reporting</param>
-		/// <param name="cancellationToken">Allows for cancellation during processing</param>
+		/// <param name="cancellationTokenSource">Allows for cancellation during processing</param>
 		/// <returns>A task representing success</returns>
-		public async Task SaveChanges(IProgress<ProgressStatus> progress, CancellationToken cancellationToken)
+		public async Task SaveChanges(IProgress<ProgressStatus> progress, CancellationTokenSource cancellationTokenSource)
 		{
 			var progressStatus = new ProgressStatus()
 			{

MatterControlLib/ApplicationView/Config/RunningTasksConfig.cs

@@ -100,7 +100,7 @@ namespace MatterHackers.MatterControl
 			};
 		}
 
-		public Task Execute(string taskTitle, object owner, Func<IProgress<ProgressStatus>, CancellationToken, Task> func, RunningTaskOptions taskActions = null)
+		public Task Execute(string taskTitle, object owner, Func<IProgress<ProgressStatus>, CancellationTokenSource, Task> func, RunningTaskOptions taskActions = null)
 		{
 			var tokenSource = new CancellationTokenSource();
 
@@ -117,7 +117,7 @@ namespace MatterHackers.MatterControl
 			{
 				try
 				{
-					await func?.Invoke(taskDetails, tokenSource.Token);
+					await func?.Invoke(taskDetails, tokenSource);
 				}
 				catch
 				{

MatterControlLib/ApplicationView/ISceneContext.cs

@@ -82,7 +82,7 @@ namespace MatterHackers.MatterControl
 
 		Task LoadLibraryContent(ILibraryItem libraryItem);
 
-		Task SaveChanges(IProgress<ProgressStatus> progress, CancellationToken cancellationToken);
+		Task SaveChanges(IProgress<ProgressStatus> progress, CancellationTokenSource cancellationToken);
 
 		// TODO: Isolate printer specifics from ISceneContext
 

MatterControlLib/ConfigurationPage/PrintLeveling/SetupWizards/XyCalibrationWizard.cs

@@ -153,7 +153,7 @@ namespace MatterHackers.MatterControl.ConfigurationPage.PrintLeveling
 			originalEditContext = printer.Bed.EditContext;
 			Task.Run(() =>
 			{
-				printer.Bed.SaveChanges(null, CancellationToken.None);
+				printer.Bed.SaveChanges(null, null);
 			});
 
 			// loop until we are done calibrating

MatterControlLib/CustomWidgets/ExportPrintItemPage.cs

@@ -230,12 +230,12 @@ namespace MatterHackers.MatterControl
 							ApplicationController.Instance.Tasks.Execute(
 								"Saving".Localize() + "...",
 								printer,
-								async (reporter, cancellationToken) =>
+								async (reporter, cancellationTokenSource) =>
 								{
 									string path = openParams.FolderPath;
 									if (!string.IsNullOrEmpty(path))
 									{
-										await exportPlugin.Generate(libraryItems, path, reporter, cancellationToken);
+										await exportPlugin.Generate(libraryItems, path, reporter, cancellationTokenSource.Token);
 									}
 								});
 						});
@@ -264,7 +264,7 @@ namespace MatterHackers.MatterControl
 							ApplicationController.Instance.Tasks.Execute(
 								"Exporting".Localize() + "...",
 								printer,
-								async (reporter, cancellationToken) =>
+								async (reporter, cancellationTokenSource) =>
 								{
 									string extension = Path.GetExtension(savePath);
 									if (!extension.Equals(targetExtension, StringComparison.OrdinalIgnoreCase))
@@ -281,7 +281,7 @@ namespace MatterHackers.MatterControl
 											gCodeExport.CenterOnBed = centerOnBed;
 										}
 
-										exportErrors = await exportPlugin.Generate(libraryItems, savePath, reporter, cancellationToken);
+										exportErrors = await exportPlugin.Generate(libraryItems, savePath, reporter, cancellationTokenSource.Token);
 									}
 
 									if (exportErrors == null || exportErrors.Count == 0)

MatterControlLib/DesignTools/Braille/BrailleCardObject3D.cs

@@ -133,6 +133,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 		}
 	}

MatterControlLib/DesignTools/Braille/BrailleObject3D.cs

@@ -263,8 +263,9 @@ namespace MatterHackers.MatterControl.DesignTools
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
-			return Task.CompletedTask;
+			return base.Rebuild();
 		}
 	}
 }

MatterControlLib/DesignTools/EditorTools/DesignApps/Parts/RibbonWithNameObject3D.cs

@@ -86,7 +86,7 @@ namespace MatterHackers.MatterControl.DesignTools
 
 			this.Mesh = null;
 			this.Invalidate(InvalidateType.Children);
-			return Task.CompletedTask;
+			return base.Rebuild();
 		}
 	}
 }

MatterControlLib/DesignTools/LithophaneObject3D.cs

@@ -30,6 +30,7 @@ either expressed or implied, of the FreeBSD Project.
 using System.ComponentModel;
 using System.ComponentModel.DataAnnotations;
 using System.Linq;
+using System.Threading;
 using System.Threading.Tasks;
 using MatterHackers.Agg;
 using MatterHackers.Agg.Platform;
@@ -88,6 +89,19 @@ namespace MatterHackers.MatterControl.Plugins.Lithophane
 			}
 		}
 
+		private CancellationTokenSource cancellationToken;
+
+		public bool IsBuilding => this.cancellationToken != null;
+
+		public void CancelBuild()
+		{
+			var threadSafe = this.cancellationToken;
+			if (threadSafe != null)
+			{
+				threadSafe.Cancel();
+			}
+		}
+
 		public override Task Rebuild()
 		{
 			this.DebugDepth("Rebuild");
@@ -110,8 +124,9 @@ namespace MatterHackers.MatterControl.Plugins.Lithophane
 
 			var rebuildLocks = this.RebuilLockAll();
 
-			ApplicationController.Instance.Tasks.Execute("Generating Lithophane".Localize(), null, (reporter, cancellationToken) =>
+			ApplicationController.Instance.Tasks.Execute("Generating Lithophane".Localize(), null, (reporter, cancellationTokenSource) =>
 			{
+				this.cancellationToken = cancellationTokenSource as CancellationTokenSource;
 				var generatedMesh = Lithophane.Generate(
 					new Lithophane.ImageBufferImageData(activeImage, this.Width),
 					this.Height,
@@ -132,16 +147,18 @@ namespace MatterHackers.MatterControl.Plugins.Lithophane
 				// Apply offset
 				this.Matrix *= Matrix4X4.CreateTranslation(-this.ImageOffset);
 
+				this.cancellationToken = null;
 				UiThread.RunOnIdle(() =>
 				{
 					rebuildLocks.Dispose();
+					this.CancelAllParentBuilding();
 					Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 				});
 
 				return Task.CompletedTask;
 			});
 
-			return Task.CompletedTask;
+			return base.Rebuild();
 		}
 	}
 }

MatterControlLib/DesignTools/Obsolete/CombineObject3D.cs

@@ -84,14 +84,14 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 			return ApplicationController.Instance.Tasks.Execute(
 				"Combine".Localize(),
 				null,
-				(reporter, cancellationToken) =>
+				(reporter, cancellationTokenSource) =>
 				{
 					var progressStatus = new ProgressStatus();
 					reporter.Report(progressStatus);
 
 					try
 					{
-						Combine(cancellationToken, reporter);
+						Combine(cancellationTokenSource.Token, reporter);
 					}
 					catch
 					{
@@ -100,10 +100,11 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 					UiThread.RunOnIdle(() =>
 					{
 						rebuildLocks.Dispose();
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 
-					return Task.CompletedTask;
+					return base.Rebuild();
 				});
 		}
 

MatterControlLib/DesignTools/Obsolete/CurveObject3D.cs

@@ -194,10 +194,11 @@ namespace MatterHackers.MatterControl.DesignTools
 				Matrix = currentMatrix;
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			Invalidate(InvalidateType.DisplayValues);
 
-			return Task.CompletedTask;
+			return base.Rebuild();
 		}
 	}
 }

MatterControlLib/DesignTools/Obsolete/FitToBoundsObject3D.cs

@@ -120,6 +120,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 				});
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 		}
 
@@ -141,6 +142,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 				});
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 		}
 
@@ -200,8 +202,9 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Matrix));
-			return Task.CompletedTask;
+			return base.Rebuild();
 		}
 
 		public override AxisAlignedBoundingBox GetAxisAlignedBoundingBox(Matrix4X4 matrix)

MatterControlLib/DesignTools/Obsolete/IntersectionObject3D.cs

@@ -78,14 +78,14 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 		{
 			var rebuildLocks = this.RebuilLockAll();
 
-			return ApplicationController.Instance.Tasks.Execute("Intersection".Localize(), null, (reporter, cancellationToken) =>
+			return ApplicationController.Instance.Tasks.Execute("Intersection".Localize(), null, (reporter, cancellationTokenSource) =>
 			{
 				var progressStatus = new ProgressStatus();
 				reporter.Report(progressStatus);
 
 				try
 				{
-					Intersect(cancellationToken, reporter);
+					Intersect(cancellationTokenSource.Token, reporter);
 				}
 				catch
 				{
@@ -94,9 +94,10 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 				UiThread.RunOnIdle(() =>
 				{
 					rebuildLocks.Dispose();
+					this.CancelAllParentBuilding();
 					Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 				});
-				return Task.CompletedTask;
+				return base.Rebuild();
 			});
 		}
 

MatterControlLib/DesignTools/Obsolete/MirrorObject3D.cs

@@ -93,6 +93,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				this.Matrix = oldMatrix;
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 
 			return Task.CompletedTask;

MatterControlLib/DesignTools/Obsolete/PinchObject3D.cs

@@ -125,6 +125,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				Matrix = currentMatrix;
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Obsolete/RotateObject3D.cs

@@ -93,6 +93,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Matrix));
 
 			return Task.CompletedTask;

MatterControlLib/DesignTools/OpenSCAD/OpenScadScriptObject3D.cs

@@ -91,6 +91,7 @@ namespace MatterHackers.MatterControl.Library
 
 			Invalidate(InvalidateType.DisplayValues);
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Operations/AlignObject3D.cs

@@ -386,6 +386,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 				});
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Matrix));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Operations/ArrayAdvancedObject3D.cs

@@ -108,6 +108,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 					UiThread.RunOnIdle(() =>
 					{
 						rebuildLock.Dispose();
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 					return Task.CompletedTask;

MatterControlLib/DesignTools/Operations/ArrayLinearObject3D.cs

@@ -98,6 +98,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 
 						SourceContainer.Visible = false;
 						rebuildLock.Dispose();
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 
 						return Task.CompletedTask;

MatterControlLib/DesignTools/Operations/ArrayRadialObject3D.cs

@@ -135,6 +135,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 					UiThread.RunOnIdle(() =>
 					{
 						rebuildLock.Dispose();
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 					return Task.CompletedTask;

MatterControlLib/DesignTools/Operations/CurveObject3D_2.cs

@@ -227,6 +227,7 @@ namespace MatterHackers.MatterControl.DesignTools
 					{
 						rebuildLocks.Dispose();
 						Invalidate(InvalidateType.DisplayValues);
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 

MatterControlLib/DesignTools/Operations/CurveObject3D_3.cs

@@ -162,6 +162,19 @@ namespace MatterHackers.MatterControl.DesignTools
 			}
 		}
 
+		private CancellationTokenSource cancellationToken;
+
+		public bool IsBuilding => this.cancellationToken != null;
+
+		public void CancelBuild()
+		{
+			var threadSafe = this.cancellationToken;
+			if (threadSafe != null)
+			{
+				threadSafe.Cancel();
+			}
+		}
+
 		public override Task Rebuild()
 		{
 			this.DebugDepth("Rebuild");
@@ -197,8 +210,9 @@ namespace MatterHackers.MatterControl.DesignTools
 			return ApplicationController.Instance.Tasks.Execute(
 				"Curve".Localize(),
 				null,
-				(reporter, cancellationToken) =>
+				(reporter, cancellationTokenSource) =>
 				{
+					this.cancellationToken = cancellationTokenSource as CancellationTokenSource;
 					var sourceAabb = this.SourceContainer.GetAxisAlignedBoundingBox();
 
 					var radius = diameter / 2;
@@ -295,10 +309,12 @@ namespace MatterHackers.MatterControl.DesignTools
 						list.AddRange(curvedChildren);
 					});
 
+					this.cancellationToken = null;
 					UiThread.RunOnIdle(() =>
 					{
 						rebuildLocks.Dispose();
 						Invalidate(InvalidateType.DisplayValues);
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 

MatterControlLib/DesignTools/Operations/DecimateObject3D.cs

@@ -172,6 +172,7 @@ namespace MatterHackers.MatterControl.DesignTools
 					{
 						rebuildLocks.Dispose();
 						Invalidate(InvalidateType.DisplayValues);
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 

MatterControlLib/DesignTools/Operations/FindSliceObject3D.cs

@@ -182,6 +182,7 @@ namespace MatterHackers.MatterControl.DesignTools
 					{
 						rebuildLocks.Dispose();
 						Invalidate(InvalidateType.DisplayValues);
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 

MatterControlLib/DesignTools/Operations/FitToBoundsObject3D_2.cs

@@ -223,6 +223,8 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 				}
 			}
 
+			this.CancelAllParentBuilding();
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Matrix | additonalInvalidate));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Operations/FitToBoundsObject3D_3.cs

@@ -191,6 +191,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Matrix | additonalInvalidate));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Operations/FitToCylinderObject3D.cs

@@ -172,6 +172,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Matrix));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Operations/HollowOutObject3D.cs

@@ -144,6 +144,7 @@ namespace MatterHackers.MatterControl.DesignTools
 					{
 						rebuildLocks.Dispose();
 						Invalidate(InvalidateType.DisplayValues);
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 

MatterControlLib/DesignTools/Operations/Image/ImageToPathObject3D.cs

@@ -370,6 +370,7 @@ namespace MatterHackers.MatterControl.DesignTools
 					UiThread.RunOnIdle(() =>
 					{
 						rebuildLock.Dispose();
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Path));
 					});
 

MatterControlLib/DesignTools/Operations/Image/ImageToPathObject3D_2.cs

@@ -415,6 +415,7 @@ namespace MatterHackers.MatterControl.DesignTools
 					{
 						rebuildLock.Dispose();
 						Invalidate(InvalidateType.DisplayValues);
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Path));
 					});
 

MatterControlLib/DesignTools/Operations/MirrorObject3D_2.cs

@@ -113,6 +113,7 @@ namespace MatterHackers.MatterControl.DesignTools
 						UiThread.RunOnIdle(() =>
 						{
 							rebuildLock.Dispose();
+							this.CancelAllParentBuilding();
 							Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 						});
 

MatterControlLib/DesignTools/Operations/Path/InflatePathObject3D.cs

@@ -103,6 +103,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 				this.Mesh = this.VertexSource.Extrude(Constants.PathPolygonsHeight);
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Path));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Operations/Path/LinearExtrudeObject3D.cs

@@ -189,6 +189,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 					{
 						rebuildLock.Dispose();
 						Invalidate(InvalidateType.DisplayValues);
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 					});
 

MatterControlLib/DesignTools/Operations/Path/MergePathObject3D.cs

@@ -83,14 +83,14 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 			return ApplicationController.Instance.Tasks.Execute(
 				operationName,
 				null,
-				(reporter, cancellationToken) =>
+				(reporter, cancellationTokenSource) =>
 				{
 					var progressStatus = new ProgressStatus();
 					reporter.Report(progressStatus);
 
 					try
 					{
-						Merge(reporter, cancellationToken);
+						Merge(reporter, cancellationTokenSource.Token);
 					}
 					catch
 					{
@@ -102,6 +102,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 					UiThread.RunOnIdle(() =>
 					{
 						rebuildLocks.Dispose();
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 					return Task.CompletedTask;

MatterControlLib/DesignTools/Operations/Path/OutlinePathObject3D.cs

@@ -114,6 +114,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 
 			Invalidate(InvalidateType.DisplayValues);
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Path));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Operations/Path/RevolveObject3D.cs

@@ -150,6 +150,19 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 			}
 		}
 
+		private CancellationTokenSource cancellationToken;
+
+		public bool IsBuilding => this.cancellationToken != null;
+
+		public void CancelBuild()
+		{
+			var threadSafe = this.cancellationToken;
+			if (threadSafe != null)
+			{
+				threadSafe.Cancel();
+			}
+		}
+
 		public override Task Rebuild()
 		{
 			this.DebugDepth("Rebuild");
@@ -176,8 +189,9 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 			return ApplicationController.Instance.Tasks.Execute(
 				"Revolve".Localize(),
 				null,
-				(reporter, cancellationToken) =>
+				(reporter, cancellationTokenSource) =>
 				{
+					this.cancellationToken = cancellationTokenSource as CancellationTokenSource;
 					var vertexSource = this.VertexSource;
 					var pathBounds = vertexSource.GetBounds();
 					vertexSource = vertexSource.Translate(-pathBounds.Left - axisPosition, 0);
@@ -197,9 +211,11 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 
 					Mesh = mesh;
 
+					this.cancellationToken = null;
 					UiThread.RunOnIdle(() =>
 					{
 						rebuildLock.Dispose();
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 

MatterControlLib/DesignTools/Operations/Path/SmoothPathObject3D.cs

@@ -107,6 +107,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 					{
 						rebuildLock.Dispose();
 						this.Invalidate(InvalidateType.DisplayValues);
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Path));
 					});
 					return Task.CompletedTask;

MatterControlLib/DesignTools/Operations/PlaneCutObject3D.cs

@@ -175,6 +175,7 @@ namespace MatterHackers.MatterControl.DesignTools
 					{
 						rebuildLocks.Dispose();
 						Invalidate(InvalidateType.DisplayValues);
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 

MatterControlLib/DesignTools/Operations/RepairObject3D.cs

@@ -74,7 +74,7 @@ namespace MatterHackers.MatterControl.DesignTools
 
 			return TaskBuilder(
 				"Repair".Localize(),
-				(reporter, cancellationToken) =>
+				(reporter, cancellationTokenSource) =>
 				{
 					SourceContainer.Visible = true;
 					RemoveAllButSource();
@@ -88,7 +88,7 @@ namespace MatterHackers.MatterControl.DesignTools
 						var originalMesh = sourceItem.Mesh;
 						inititialFaces += originalMesh.Faces.Count;
 						inititialVertices += originalMesh.Vertices.Count;
-						var repairedMesh = Repair(originalMesh, cancellationToken);
+						var repairedMesh = Repair(originalMesh, cancellationTokenSource.Token);
 						finalFaces += repairedMesh.Faces.Count;
 						finalVertices += repairedMesh.Vertices.Count;
 
@@ -111,6 +111,7 @@ namespace MatterHackers.MatterControl.DesignTools
 					{
 						rebuildLocks.Dispose();
 						Invalidate(InvalidateType.DisplayValues);
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 

MatterControlLib/DesignTools/Operations/RotateObject3D_2.cs

@@ -152,6 +152,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 				ItemWithTransform.Matrix = RotationMatrix;
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Matrix));
 
 			return Task.CompletedTask;

MatterControlLib/DesignTools/Operations/ScaleObject3D.cs

@@ -245,6 +245,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Matrix));
 
 			return Task.CompletedTask;

MatterControlLib/DesignTools/Operations/ScaleObject3D_2.cs

@@ -297,6 +297,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Matrix));
 
 			return Task.CompletedTask;

MatterControlLib/DesignTools/Operations/ScaleObject3D_3.cs

@@ -373,6 +373,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 
 
 			Invalidate(InvalidateType.DisplayValues);
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Matrix));
 
 			return Task.CompletedTask;

MatterControlLib/DesignTools/Operations/TransformWrapperObject3D.cs

@@ -181,7 +181,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 
 			scene.SelectedItem = this;
 
-
+			this.CancelAllParentBuilding();
 			parent?.Invalidate(new InvalidateArgs(parent, InvalidateType.Children));
 		}
 
@@ -228,6 +228,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 
 			parentLock?.Dispose();
 
+			this.CancelAllParentBuilding();
 			parent?.Invalidate(new InvalidateArgs(parent, InvalidateType.Children));
 		}
 	}

MatterControlLib/DesignTools/Operations/TranslateObject3D.cs

@@ -106,6 +106,7 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 				ItemWithTransform.Matrix = Matrix4X4.CreateTranslation(Translation);
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Matrix));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Operations/TwistObject3D.cs

@@ -326,6 +326,7 @@ namespace MatterHackers.MatterControl.DesignTools
 					UiThread.RunOnIdle(() =>
 					{
 						rebuildLocks.Dispose();
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 						Invalidate(InvalidateType.DisplayValues);
 					});

MatterControlLib/DesignTools/Primitives/BaseObject3D.cs

@@ -259,6 +259,7 @@ namespace MatterHackers.MatterControl.DesignTools
 					{
 						rebuildLock.Dispose();
 						Invalidate(InvalidateType.DisplayValues);
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 

MatterControlLib/DesignTools/Primitives/BoxPathObject3D.cs

@@ -129,6 +129,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Path));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/ConeObject3D.cs

@@ -107,6 +107,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/CubeObject3D.cs

@@ -146,8 +146,11 @@ namespace MatterHackers.MatterControl.DesignTools
 				}
 			}
 
+			// if any of our parest are re-bulding cancel it as we just changed and they need to start over
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
-			return Task.CompletedTask;
+
+			return base.Rebuild();
 		}
 
 		public void UpdateControls(PublicPropertyChange change)

MatterControlLib/DesignTools/Primitives/CylinderObject3D.cs

@@ -207,6 +207,7 @@ namespace MatterHackers.MatterControl.DesignTools
 			
 			Invalidate(InvalidateType.DisplayValues);
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/DescriptionObject3D.cs

@@ -220,6 +220,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/HalfCylinderObject3D.cs

@@ -112,6 +112,7 @@ namespace MatterHackers.MatterControl.DesignTools
 
 			Invalidate(InvalidateType.DisplayValues);
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/HalfSphereObject3D.cs

@@ -135,6 +135,7 @@ namespace MatterHackers.MatterControl.DesignTools
 
 			Invalidate(InvalidateType.DisplayValues);
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/HalfWedgeObject3D.cs

@@ -102,6 +102,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/ImageObject3D.cs

@@ -114,6 +114,7 @@ namespace MatterHackers.MatterControl.DesignTools
 					_image = image;
 
 					// send the invalidate on image change
+					this.CancelAllParentBuilding();
 					Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Image));
 					Invalidate(InvalidateType.DisplayValues);
 				}

MatterControlLib/DesignTools/Primitives/MarchingSquaresObject3D.cs

@@ -128,6 +128,7 @@ namespace MatterHackers.MatterControl.DesignTools
 
 				Invalidate(InvalidateType.DisplayValues);
 
+				this.CancelAllParentBuilding();
 				Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 				return Task.CompletedTask;
 			});

MatterControlLib/DesignTools/Primitives/MeasureToolObject3D.cs

@@ -228,6 +228,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/OperationSourceContainerObject3D.cs

@@ -44,8 +44,8 @@ namespace MatterHackers.MatterControl.DesignTools.Operations
 {
 	public class OperationSourceContainerObject3D : Object3D
 	{
-		public static Func<string, Func<IProgress<ProgressStatus>, CancellationToken, Task>, Task> TaskBuilder { get; set; } =
+		public static Func<string, Func<IProgress<ProgressStatus>, CancellationTokenSource, Task>, Task> TaskBuilder { get; set; } =
-			(name, func) => Task.Run(() => func(null, CancellationToken.None));
+			(name, func) => Task.Run(() => func(null, null));
 
 		public override Mesh Mesh
 		{

MatterControlLib/DesignTools/Primitives/PyramidObject3D.cs

@@ -103,6 +103,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/RingObject3D.cs

@@ -232,6 +232,7 @@ namespace MatterHackers.MatterControl.DesignTools
 
 			Invalidate(InvalidateType.DisplayValues);
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/SetTemperatureObject3D.cs

@@ -105,6 +105,7 @@ namespace MatterHackers.MatterControl.DesignTools
 
 			UpdateTexture();
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/SphereObject3D.cs

@@ -156,6 +156,7 @@ namespace MatterHackers.MatterControl.DesignTools
 
 			Invalidate(InvalidateType.DisplayValues);
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/TemperatureTowerObject3D.cs

@@ -186,6 +186,7 @@ namespace MatterHackers.MatterControl.DesignTools
 
 			Invalidate(InvalidateType.DisplayValues);
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/TextObject3D.cs

@@ -191,6 +191,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				{
 					rebuildLock.Dispose();
 					Invalidate(InvalidateType.DisplayValues);
+					this.CancelAllParentBuilding();
 					Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 				});
 			});

MatterControlLib/DesignTools/Primitives/TextPathObject3D.cs

@@ -153,6 +153,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				this.Mesh = this.VertexSource.Extrude(Constants.PathPolygonsHeight);
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Path));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/TorusObject3D.cs

@@ -158,6 +158,7 @@ namespace MatterHackers.MatterControl.DesignTools
 
 			Invalidate(InvalidateType.DisplayValues);
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/WedgeObject3D.cs

@@ -132,6 +132,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 
 			return Task.CompletedTask;

MatterControlLib/DesignTools/Primitives/WedgeObject3D_2.cs

@@ -146,6 +146,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 
 			return Task.CompletedTask;

MatterControlLib/DesignTools/Primitives/XyCalibrationFaceObject3D.cs

@@ -157,6 +157,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/Primitives/XyCalibrationTabObject3D.cs

@@ -149,6 +149,7 @@ namespace MatterHackers.MatterControl.DesignTools
 				}
 			}
 
+			this.CancelAllParentBuilding();
 			Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Mesh));
 			return Task.CompletedTask;
 		}

MatterControlLib/DesignTools/SupportGenerator.cs

@@ -144,6 +144,11 @@ namespace MatterHackers.MatterControl.DesignTools
 		}
 
 		public Task Create(IProgress<ProgressStatus> progress, CancellationToken cancellationToken)
+		{
+			return Create(progress, null);
+		}
+
+		public Task Create(IProgress<ProgressStatus> progress, CancellationTokenSource cancellationTokenSource)
 		{
 			var selectedItem = scene.SelectedItem;
 

MatterControlLib/HelpIndex.cs

@@ -80,11 +80,11 @@ namespace MatterControlLib
 			return ApplicationController.Instance.Tasks.Execute(
 				"Preparing help index".Localize(),
 				null,
-				(progress, cancellationToken) =>
+				(progress, cancellationTokenSource) =>
 				{
 					string relativePath = System.IO.Path.Combine("OemSettings", "help-docs.zip");
 
-					IndexZipFile(relativePath, progress, cancellationToken);
+					IndexZipFile(relativePath, progress, cancellationTokenSource.Token);
 
 					return Task.CompletedTask;
 				});

MatterControlLib/Library/Export/GCodeExport.cs

@@ -254,7 +254,7 @@ namespace MatterHackers.MatterControl.Library.Export
 									Printer,
 									(reporter, cancellationToken2) =>
 									{
-										return Slicer.SliceItem(loadedItem, gcodePath, Printer, reporter, cancellationToken2);
+										return Slicer.SliceItem(loadedItem, gcodePath, Printer, reporter, cancellationToken2.Token);
 									});
 
 								Printer.Settings.SetValue(SettingsKey.spiral_vase, oldSpiralVaseSetting ? "1" : "0");

MatterControlLib/PartPreviewWindow/View3D/Actions/CombineObject3D_2.cs

@@ -43,9 +43,11 @@ using MatterHackers.VectorMath;
 namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 {
 	[ShowUpdateButton(false)]
-	public class CombineObject3D_2 : OperationSourceContainerObject3D, IPropertyGridModifier
+	public class CombineObject3D_2 : OperationSourceContainerObject3D, IPropertyGridModifier, IBuildsOnThread
 	{
-		public CombineObject3D_2()
+        private CancellationTokenSource cancellationToken;
+
+        public CombineObject3D_2()
 		{
 			Name = "Combine";
 		}
@@ -67,6 +69,8 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 		private IplicitSurfaceMethod MeshAnalysis { get; set; }
 		private ProcessingResolution InputResolution { get; set; } = ProcessingResolution._64;
 #endif
+		public bool IsBuilding => this.cancellationToken != null;
+		
 		public override Task Rebuild()
 		{
 			this.DebugDepth("Rebuild");
@@ -76,22 +80,25 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 			return ApplicationController.Instance.Tasks.Execute(
 				"Combine".Localize(),
 				null,
-				(reporter, cancellationToken) =>
+				(reporter, cancellationTokenSource) =>
 				{
+					this.cancellationToken = cancellationTokenSource as CancellationTokenSource;
 					var progressStatus = new ProgressStatus();
 					reporter.Report(progressStatus);
 
 					try
 					{
-						Combine(cancellationToken, reporter);
+						Combine(cancellationTokenSource.Token, reporter);
 					}
 					catch
 					{
 					}
 
+					this.cancellationToken = null;
 					UiThread.RunOnIdle(() =>
 					{
 						rebuildLocks.Dispose();
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 					return Task.CompletedTask;
@@ -197,5 +204,14 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 			change.SetRowVisible(nameof(MeshAnalysis), () => Processing != ProcessingModes.Polygons);
 			change.SetRowVisible(nameof(InputResolution), () => Processing != ProcessingModes.Polygons && MeshAnalysis == IplicitSurfaceMethod.Grid);
 		}
-	}
+
+        public void CancelBuild()
+        {
+			var threadSafe = this.cancellationToken;
+			if(threadSafe != null)
+            {
+				threadSafe.Cancel();
+            }
+        }
+    }
 }

MatterControlLib/PartPreviewWindow/View3D/Actions/IntersectionObject3D_2.cs

@@ -68,6 +68,19 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 		private ProcessingResolution InputResolution { get; set; } = ProcessingResolution._64;
 #endif
 
+		private CancellationTokenSource cancellationToken;
+
+		public bool IsBuilding => this.cancellationToken != null;
+
+		public void CancelBuild()
+		{
+			var threadSafe = this.cancellationToken;
+			if (threadSafe != null)
+			{
+				threadSafe.Cancel();
+			}
+		}
+
 		public override Task Rebuild()
 		{
 			this.DebugDepth("Rebuild");
@@ -77,22 +90,25 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 			return ApplicationController.Instance.Tasks.Execute(
 				"Intersection".Localize(),
 				null,
-				(reporter, cancellationToken) =>
+				(reporter, cancellationTokenSource) =>
 				{
+					this.cancellationToken = cancellationTokenSource as CancellationTokenSource;
 					var progressStatus = new ProgressStatus();
 					reporter.Report(progressStatus);
 
 					try
 					{
-						Intersect(cancellationToken, reporter);
+						Intersect(cancellationTokenSource.Token, reporter);
 					}
 					catch
 					{
 					}
 
+					this.cancellationToken = null;
 					UiThread.RunOnIdle(() =>
 					{
 						rebuildLocks.Dispose();
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 

MatterControlLib/PartPreviewWindow/View3D/Actions/SubtractAndReplaceObject3D.cs

@@ -202,11 +202,11 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 			var rebuildLocks = this.RebuilLockAll();
 
 			// spin up a task to calculate the paint
-			return ApplicationController.Instance.Tasks.Execute("Replacing".Localize(), null, (reporter, cancellationToken) =>
+			return ApplicationController.Instance.Tasks.Execute("Replacing".Localize(), null, (reporter, cancellationTokenSource) =>
 			{
 				try
 				{
-					SubtractAndReplace(cancellationToken, reporter);
+					SubtractAndReplace(cancellationTokenSource.Token, reporter);
 				}
 				catch
 				{
@@ -215,6 +215,7 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 				UiThread.RunOnIdle(() =>
 				{
 					rebuildLocks.Dispose();
+					this.CancelAllParentBuilding();
 					Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 				});
 

MatterControlLib/PartPreviewWindow/View3D/Actions/SubtractAndReplaceObject3D_2.cs

@@ -129,16 +129,32 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 			}
 		}
 
+		private CancellationTokenSource cancellationToken;
+
+		public bool IsBuilding => this.cancellationToken != null;
+
+		public void CancelBuild()
+		{
+			var threadSafe = this.cancellationToken;
+			if (threadSafe != null)
+			{
+				threadSafe.Cancel();
+			}
+		}
+
 		public override Task Rebuild()
 		{
 			var rebuildLocks = this.RebuilLockAll();
 
 			// spin up a task to calculate the paint
-			return ApplicationController.Instance.Tasks.Execute("Replacing".Localize(), null, (reporter, cancellationToken) =>
+			return ApplicationController.Instance.Tasks.Execute("Replacing".Localize(),
+				null,
+				(reporter, cancellationTokenSource) =>
 			{
+				this.cancellationToken = cancellationTokenSource as CancellationTokenSource;
 				try
 				{
-					SubtractAndReplace(cancellationToken, reporter);
+					SubtractAndReplace(cancellationTokenSource.Token, reporter);
 					var newComputedChildren = new SelectedChildren();
 
 					foreach (var id in SelectedChildren)
@@ -152,9 +168,11 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 				{
 				}
 
+				this.cancellationToken = null;
 				UiThread.RunOnIdle(() =>
 				{
 					rebuildLocks.Dispose();
+					this.CancelAllParentBuilding();
 					Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 				});
 

MatterControlLib/PartPreviewWindow/View3D/Actions/SubtractObject3D.cs

@@ -85,14 +85,14 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 			return ApplicationController.Instance.Tasks.Execute(
 				"Subtract".Localize(),
 				null,
-				(reporter, cancellationToken) =>
+				(reporter, cancellationTokenSource) =>
 				{
 					var progressStatus = new ProgressStatus();
 					reporter.Report(progressStatus);
 
 					try
 					{
-						Subtract(cancellationToken, reporter);
+						Subtract(cancellationTokenSource.Token, reporter);
 					}
 					catch
 					{
@@ -101,6 +101,7 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 					UiThread.RunOnIdle(() =>
 					{
 						rebuildLocks.Dispose();
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 

MatterControlLib/PartPreviewWindow/View3D/Actions/SubtractObject3D_2.cs

@@ -45,7 +45,7 @@ using MatterHackers.VectorMath;
 namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 {
 	[ShowUpdateButton(false)]
-	public class SubtractObject3D_2 : OperationSourceContainerObject3D, ISelectableChildContainer, ICustomEditorDraw, IPropertyGridModifier
+	public class SubtractObject3D_2 : OperationSourceContainerObject3D, ISelectableChildContainer, ICustomEditorDraw, IPropertyGridModifier, IBuildsOnThread
 	{
 		public SubtractObject3D_2()
 		{
@@ -130,6 +130,19 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 			}
 		}
 
+		private CancellationTokenSource cancellationToken;
+
+		public bool IsBuilding => this.cancellationToken != null;
+
+		public void CancelBuild()
+		{
+			var threadSafe = this.cancellationToken;
+			if (threadSafe != null)
+			{
+				threadSafe.Cancel();
+			}
+		}
+
 		public override Task Rebuild()
 		{
 			this.DebugDepth("Rebuild");
@@ -139,22 +152,25 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 			return ApplicationController.Instance.Tasks.Execute(
 				"Subtract".Localize(),
 				null,
-				(reporter, cancellationToken) =>
+				(reporter, cancellationTokenSource) =>
 				{
+					this.cancellationToken = cancellationTokenSource as CancellationTokenSource;
 					var progressStatus = new ProgressStatus();
 					reporter.Report(progressStatus);
 
 					try
 					{
-						Subtract(cancellationToken, reporter);
+						Subtract(cancellationTokenSource.Token, reporter);
 					}
 					catch
 					{
 					}
 
+					this.cancellationToken = null;
 					UiThread.RunOnIdle(() =>
 					{
 						rebuildLocks.Dispose();
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 

MatterControlLib/PartPreviewWindow/View3D/Actions/SubtractPathObject3D.cs

@@ -106,14 +106,14 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 			return ApplicationController.Instance.Tasks.Execute(
 				"Subtract".Localize(),
 				null,
-				(reporter, cancellationToken) =>
+				(reporter, cancellationTokenSource) =>
 				{
 					var progressStatus = new ProgressStatus();
 					reporter.Report(progressStatus);
 
 					try
 					{
-						Subtract(cancellationToken, reporter);
+						Subtract(cancellationTokenSource.Token, reporter);
 					}
 					catch
 					{
@@ -133,6 +133,7 @@ namespace MatterHackers.MatterControl.PartPreviewWindow.View3D
 					UiThread.RunOnIdle(() =>
 					{
 						rebuildLocks.Dispose();
+						this.CancelAllParentBuilding();
 						Parent?.Invalidate(new InvalidateArgs(this, InvalidateType.Children));
 					});
 

MatterControlLib/PartPreviewWindow/View3D/SceneActions.cs

@@ -78,7 +78,7 @@ namespace MatterHackers.MatterControl.PartPreviewWindow
 					await ApplicationController.Instance.Tasks.Execute(
 						"Ungroup".Localize(),
 						null,
-						(reporter, cancellationToken) =>
+						(reporter, cancellationTokenSource) =>
 						{
 							var progressStatus = new ProgressStatus();
 							reporter.Report(progressStatus);
@@ -90,16 +90,16 @@ namespace MatterHackers.MatterControl.PartPreviewWindow
 							// try to cut it up into multiple meshes
 							progressStatus.Status = "Split".Localize();
 							
-							var cleanMesh = selectedItem.Mesh.Copy(cancellationToken);
+							var cleanMesh = selectedItem.Mesh.Copy(cancellationTokenSource.Token);
 							cleanMesh.MergeVertices(.01);
 
-							var discreetMeshes = CreateDiscreteMeshes.SplitVolumesIntoMeshes(cleanMesh, cancellationToken, (double progress0To1, string processingState) =>
+							var discreetMeshes = CreateDiscreteMeshes.SplitVolumesIntoMeshes(cleanMesh, cancellationTokenSource.Token, (double progress0To1, string processingState) =>
 							{
 								progressStatus.Progress0To1 = .5 + progress0To1 * .5;
 								progressStatus.Status = processingState;
 								reporter.Report(progressStatus);
 							});
-							if (cancellationToken.IsCancellationRequested)
+							if (cancellationTokenSource.IsCancellationRequested)
 							{
 								return Task.CompletedTask;
 							}

Submodules/MatterSlice

@@ -1 +1 @@
-Subproject commit 17fb182f8ef221a9fbe94eb831cef9956c6c1ba6
+Subproject commit dc55feeb1e043b0772aa2c21b4d6947e1cccc14f

Submodules/agg-sharp

@@ -1 +1 @@
-Subproject commit e996ffa5eb793d8b7e4d832b9d1b33e08bf0c152
+Subproject commit 8c801ba65845521e2a0e13a00f318952caa80336