fixed #259

src/Shared/HandyControlDemo_Shared/App.xaml.cs

@@ -15,9 +15,10 @@ namespace HandyControlDemo
 {
     public partial class App
     {
-        // ReSharper disable once NotAccessedField.Local
-        [SuppressMessage("代码质量", "IDE0052:删除未读的私有成员", Justification = "<挂起>")]
+#pragma warning disable IDE0052
+        [SuppressMessage("ReSharper", "NotAccessedField.Local")] 
         private static Mutex AppMutex;
+#pragma warning restore IDE0052
 
         protected override void OnStartup(StartupEventArgs e)
         {

src/Shared/HandyControlDemo_Shared/Tools/Converter/String2BrushConverter.cs

@@ -10,7 +10,7 @@ namespace HandyControlDemo.Tools.Converter
     {
         public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
         {
-            return value is string str ? ResourceHelper.GetResource<Brush>(str) : default(Brush);
+            return value is string str ? ResourceHelper.GetResource<Brush>(str) : default;
         }
 
         public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)