fix: pass default value when close from control.

demo/Ursa.Demo/ViewModels/DialogDemoViewModel.cs

@@ -56,7 +56,6 @@ public class DialogDemoViewModel: ObservableObject
         var vm = new DialogWithActionViewModel();
         var result = await DialogBox.ShowOverlayAsync<DialogWithAction, DialogWithActionViewModel, bool>(
             DialogViewModel, "LocalHost");
-        Date = vm.Date;
         Result = result;
     }
 }

src/Ursa/Controls/Dialog/DialogControl.cs

@@ -74,8 +74,9 @@ public class DialogControl: ContentControl
     {
         if (this.DataContext is IDialogContext context)
         {
-            OnClose?.Invoke(this, args);
+            OnClose?.Invoke(this, Equals(sender, _closeButton) ? context.DefaultCloseResult : args);
         }
+        
         else
         {
             OnClose?.Invoke(this, null);