Create NotifyObject.cs

src/Model/NotifyObject.cs

@@ -0,0 +1,12 @@
+using System.ComponentModel;
+
+namespace LanguageEditor
+{
+    public class NotifyObject : INotifyPropertyChanged
+    {
+        public event PropertyChangedEventHandler PropertyChanged;
+
+        public void Notify(string propertyName)
+            => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+    }
+}