diff --git a/src/dialogs.bjo b/src/dialogs.bjo
index 96c632e..c32e409 100644
--- a/src/dialogs.bjo
+++ b/src/dialogs.bjo
@@ -29,9 +29,6 @@
 
 (import/class
   (Object            (: System.Object))
-  (DispatcherOpBase  (: Avalonia.Threading.DispatcherOperation))
-  (ClrType           (: System.Type))
-  (PropertyInfo      (: System.Reflection.PropertyInfo))
   (ClrString         (: System.String))
   ((ReadOnlyList %a) (: System.Collections.Generic.IReadOnlyList))
   ((EventHandler %a) (: System.EventHandler))
@@ -77,20 +74,12 @@
   ;; The UI thread, and the window a dialog belongs to.
   (ui-dispatcher (: Avalonia.Threading.Dispatcher.UIThread #:get))
   (ui-post       (: Avalonia.Threading.Dispatcher.InvokeAsync (-> Dispatcher (-> Unit) (DispatcherOp Unit))))
-  ;; Runs a function on the UI thread.
+  ;; Runs a function that starts a Task on the UI thread, and waits for the
+  ;; Task. Avalonia's dialogs take no CancellationToken, so this cannot be
+  ;; cancelled: a cancelled command stops waiting, and the dialog stays until
+  ;; it is answered.
   (on-ui         (: Avalonia.Threading.Dispatcher.InvokeAsync
-                    (-> Dispatcher (-> Unit) (DispatcherOp Unit))))
-  (op-task       (: Avalonia.Threading.DispatcherOperation.GetTask (-> DispatcherOpBase Task)))
-  ;; Waits for Tasks. Avalonia's dialogs take no CancellationToken, so this
-  ;; cannot be cancelled: a cancelled command stops at its next sync, and the
-  ;; dialog stays until it is answered.
-  (await-tasks   (: System.Threading.Tasks.Task.WhenAll (-> (Array Task) void)
-                    #:async #:uncancellable))
-  ;; What a finished Task answers. By reflection, because Bjolang reads no
-  ;; Task's Result: on a Task that is not finished, that would block.
-  (type-of       (: System.Object.GetType (-> Object ClrType)))
-  (property-of   (: System.Type.GetProperty (-> ClrType string PropertyInfo)))
-  (value-of      (: System.Reflection.PropertyInfo.GetValue (-> PropertyInfo Object Object)))
+                    (-> Dispatcher (-> (Task %a)) %a) #:async #:uncancellable))
   (answered      (: System.Threading.Tasks.Task.FromResult (-> %a (Task %a))))
   (current-app   (: Avalonia.Application.Current #:get))
   (app-lifetime  (: Avalonia.Application.ApplicationLifetime (-> Application ILifetime) #:get))
@@ -171,16 +160,10 @@
 ;; Task it makes. `none` is the answer when there is no window.
 (: (-bjo-> (-> Window (Task %a)) %a %a))
 (defbjo (run-on-ui start none)
-  (def/mutable task (: (clr-default) Task))
-  (def op (on-ui ui-dispatcher
-                 (fun ()
-                   (set! task (cast Task (cast Object (match (owner)
-                                                            ((Some w) (start w))
-                                                            (None (answered none))))))
-                   unit)))
-  (await-tasks #[(op-task (cast DispatcherOpBase (cast Object op)))])
-  (await-tasks #[task])
-  (cast %a (value-of (property-of (type-of (cast Object task)) "Result") (cast Object task))))
+  (on-ui ui-dispatcher
+         (fun () (match (owner)
+                   ((Some w) (start w))
+                   (None (answered none))))))
 
 ;; The event of what the Task that `start` makes answers, at each sync.
 ;; `none` is the answer when there is no window, or the Task fails.