solved #151

src/Shared/HandyControlDemo_Shared/ViewModel/Controls/NotificationDemoViewModel.cs

@@ -21,7 +21,11 @@ namespace HandyControlDemo.ViewModel
         public ShowAnimation ShowAnimation
         {
             get => _showAnimation;
+#if netle40
+            set => Set(nameof(ShowAnimation) ,ref _showAnimation, value);
+#else
             set => Set(ref _showAnimation, value);
+#endif
         }
 
         private bool _staysOpen = true;
@@ -29,7 +33,11 @@ namespace HandyControlDemo.ViewModel
         public bool StaysOpen
         {
             get => _staysOpen;
+#if netle40
+            set => Set(nameof(StaysOpen) ,ref _staysOpen, value);
+#else
             set => Set(ref _staysOpen, value);
+#endif
         }
     }
 }