Ensure text area size remains constant and buttons remain onscreen

- Issue MatterHackers/MCCentral#3894
Investigate failing CancelWorksAsExpected test

Library/Widgets/PrintLibraryWidget.cs

@@ -573,7 +573,7 @@ namespace MatterHackers.MatterControl.PrintLibrary
 						selectedLibraryItems.FirstOrDefault() is ILibraryAssetStream assetStream
 						&& assetStream.ContentType == "gcode")
 					{
-						// Drop handler for special case of GCode or similar (change loaded scene to new context)
+						// Change loaded scene to new context
 						printer.Bed.LoadContent(
 							new EditContext()
 							{

PartPreviewWindow/RunningTaskRow.cs

@@ -88,7 +88,7 @@ namespace MatterHackers.MatterControl.PartPreviewWindow
 			expandButton = new ExpandCheckboxButton(!string.IsNullOrWhiteSpace(title) ? title : taskDetails.Title, theme, 10)
 			{
 				VAnchor = VAnchor.Center | VAnchor.Fit,
-				HAnchor = HAnchor.Fit,
+				HAnchor = HAnchor.Stretch,
 				Checked = false,
 				Padding = 0
 			};
@@ -99,8 +99,6 @@ namespace MatterHackers.MatterControl.PartPreviewWindow
 			};
 			topRow.AddChild(expandButton);
 
-			topRow.AddChild(new HorizontalSpacer());
-
 			IconButton resumeButton = null;
 
 			var pauseButton = new IconButton(AggContext.StaticData.LoadIcon("fa-pause_12.png", theme.InvertIcons), theme)