fix: missing cancellable action

fileDialog.hs

@@ -10,13 +10,13 @@ main = do
     app <- new Application []
     onApplicationActivate app $ do
         dlg <- new FileDialog [fileDialogInitialFolder :=> fileNewForPath "/"]
-        
         window <- new GI.Gtk.ApplicationWindow [#application := app,
                                                 #title := "Wazajisho"]
-                                                
-        fileDialogSelectFolder dlg (Just window) (Nothing :: Maybe Cancellable) 
-          
-    
+        {-
+                This type is defined in the GI.Gio library, which we're importing (with import GI.Gio hiding (Application)).
+                It’s a common pattern in GTK and GIO for asynchronous functions to accept a cancellable object.
+         -}          
+        fileDialogSelectFolder dlg (Just window) (Nothing :: Maybe Cancellable) Nothing
+
     applicationRun app Nothing
     threadDelay 30000000000
-