On theme change, prevent theme change until reload completes

- Issue MatterHackers/MCCentral#4381

MatterControlLib/ConfigurationPage/ApplicationSettings/ThemePreviewButton.cs

@@ -126,6 +126,9 @@ namespace MatterHackers.MatterControl.ConfigurationPage
 			{
 				// Activate the theme
 				themeColorPanel.SetThemeColor(this.ThemeSet, primaryAccentColor, this.Mode);
+
+				// Disable further theme clicks until reload completes
+				themeColorPanel.Enabled = false;
 			};
 
 			this.AddChild(overlay);

MatterControlLib/PartPreviewWindow/View3D/View3DWidget.cs

@@ -627,7 +627,6 @@ namespace MatterHackers.MatterControl.PartPreviewWindow
 					};
 				});
 			}
-
 		}
 
 		private static void CopyPlateToPrinter(BedConfig sceneContext, PrinterConfig printer)