lang support for binding

src/Shared/HandyControlDemo_Shared/Tools/Extension/LangExtension.cs

@@ -4,6 +4,9 @@ namespace HandyControlDemo.Tools.Extension
 {
     public class LangExtension : HandyControl.Tools.Extension.LangExtension
     {
-        public override object LangSource => LangDecorator.Instance;
+        public LangExtension()
+        {
+            Source = LangDecorator.Instance;
+        }
     }
 }