Invoke via RunOnIdle to prevent blocking

- Issue MatterHackers/MCCentral#4639
[Linux] Mouse does not work in export printer dialog

MatterControlLib/PartPreviewWindow/View3D/PrinterBar/PrinterActionsBar.cs

@@ -330,10 +330,10 @@ namespace MatterHackers.MatterControl.PartPreviewWindow
 				new NamedAction()
 				{
 					Title = "Export All Settings".Localize(),
-					Action = () =>
+					Action = () => UiThread.RunOnIdle(() =>
 					{
 						ApplicationController.Instance.ExportAsMatterControlConfig(printer);
-					}
+					})
 				},
 				new ActionSeparator(),
 				new NamedAction()

appsettings.json

@@ -3,7 +3,10 @@
     "GraphicsMode": {
       "Color": 32,
       "Depth": 24,
-      "FSAASamples": 8
+      "FSAASamples": 8 
+    },
+    "ProviderTypes": {
+      "DialogProvider": "MatterHackers.Agg.Platform.GtkFileDialogProvider, PlatformGtk"
     }
   },
   "MatterControl": {