fix banner.cs

com.unity.uiwidgets/Runtime/painting/binding.cs

 using System;
+using System.Collections.Generic;
 using Unity.UIWidgets.async2;
 using Unity.UIWidgets.foundation;
 using Unity.UIWidgets.gestures;
 
         public ImageCache imageCache => _imageCache;
         ImageCache _imageCache;
-
+        readonly _SystemFontsNotifier _systemFonts = new _SystemFontsNotifier();
+        public _SystemFontsNotifier  systemFonts {
+            get { return _systemFonts; }
+        }
 
         protected virtual ImageCache createImageCache() {
             return new ImageCache();
     public static partial class painting_ {
         public static ImageCache imageCache => PaintingBinding.instance.imageCache;
+    }
+    
+    public class _SystemFontsNotifier : Listenable {
+        HashSet<VoidCallback> _systemFontsCallbacks = new HashSet<VoidCallback>();
+
+        void notifyListeners () {
+            foreach (VoidCallback callback in _systemFontsCallbacks) {
+                callback();
+            }
+        }
+    
+        public void addListener(VoidCallback listener) {
+            _systemFontsCallbacks.Add(listener);
+        }
+
+        public void removeListener(VoidCallback listener) {
+            _systemFontsCallbacks.Remove(listener);
+        }
     }
 }

com.unity.uiwidgets/Runtime/widgets/banner.cs

             BannerLocation? location,
             Color color = null,
             TextStyle textStyle = null
-        ) {
+        ) : base (repaint: PaintingBinding.instance.systemFonts) {
             D.assert(message != null);
             D.assert(location != null);
             this.color = color ?? BannerConstants._kColor;
             base.debugFillProperties(properties);
             properties.add(new StringProperty("message", message, showName: false));
             properties.add(new EnumProperty<BannerLocation?>("location", location));
-            properties.add(new DiagnosticsProperty<Color>("color", color, showName: false));
+            properties.add(new ColorProperty("color", color, showName: false));
             textStyle?.debugFillProperties(properties);
         }
     }