temporary fix

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

 
     public abstract class TextSelectionControls {
         public abstract Widget buildHandle(BuildContext context, TextSelectionHandleType type, float textLineHeight);
-
-        public abstract Widget buildToolbar(BuildContext context, Rect globalEditableRegion, Offset position,
-            TextSelectionDelegate selectionDelegate);
+        public abstract Offset getHandleAnchor(TextSelectionHandleType type, float textLineHeight);
+        public abstract Widget buildToolbar(
+            BuildContext context, 
+            Rect globalEditableRegion, 
+            float textLineHeight,
+            Offset position,
+            List<TextSelectionPoint> endpoints,
+            TextSelectionDelegate selectionDelegate
+            );
+        public abstract Size getHandleSize(float textLineHeight);
-        public virtual bool canCut(TextSelectionDelegate selectionDelegate) {
-            return !selectionDelegate.textEditingValue.selection.isCollapsed;
+        public virtual bool canCut(TextSelectionDelegate _delegate) {
+            return _delegate.cutEnabled && !_delegate.textEditingValue.selection.isCollapsed;
-        public virtual bool canCopy(TextSelectionDelegate selectionDelegate) {
-            return !selectionDelegate.textEditingValue.selection.isCollapsed;
+
+        bool canCopy(TextSelectionDelegate _delegate) {
+            return _delegate.copyEnabled && !_delegate.textEditingValue.selection.isCollapsed;
-        public virtual bool canPaste(TextSelectionDelegate selectionDelegate) {
-            // TODO in flutter: return false when clipboard is empty
-            return true;
+        bool canPaste(TextSelectionDelegate _delegate) {
+            // TODO(goderbauer): return false when clipboard is empty, https://github.com/flutter/flutter/issues/11254
+            return _delegate.pasteEnabled;
-        public virtual bool canSelectAll(TextSelectionDelegate selectionDelegate) {
-            return selectionDelegate.textEditingValue.text.isNotEmpty() &&
-                   selectionDelegate.textEditingValue.selection.isCollapsed;
+        bool canSelectAll(TextSelectionDelegate _delegate) {
+            return _delegate.selectAllEnabled 
+                   && _delegate.textEditingValue.text.isNotEmpty() 
+                   && _delegate.textEditingValue.selection.isCollapsed;
+
 
         public void handleCut(TextSelectionDelegate selectionDelegate) {
             TextEditingValue value = selectionDelegate.textEditingValue;
     }
 
     public class TextSelectionOverlay {
-        public TextSelectionOverlay(TextEditingValue value = null,
-            BuildContext context = null, Widget debugRequiredFor = null,
+        public TextSelectionOverlay(
+            TextEditingValue value = null,
+            BuildContext context = null, 
+            Widget debugRequiredFor = null,
             LayerLink layerLink = null,
             RenderEditable renderObject = null,
             TextSelectionControls selectionControls = null,

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

 using Unity.UIWidgets.scheduler2;
 
 namespace Unity.UIWidgets.widgets {
-    public class TickerMode : InheritedWidget {
+    public class TickerMode : StatelessWidget {
-            : base(key, child) {
+            : base(key:key) {
+            D.assert(enabled != null);
+            this.child = child;
-
+        public readonly Widget child;
-            var widget = (TickerMode) context.inheritFromWidgetOfExactType(typeof(TickerMode));
-            return widget != null ? widget.enabled : true;
+            _EffectiveTickerMode widget = context.dependOnInheritedWidgetOfExactType<_EffectiveTickerMode>();
+            return widget?.enabled ?? true;
-        public override bool updateShouldNotify(InheritedWidget oldWidget) {
-            return enabled != ((TickerMode) oldWidget).enabled;
+        public override Widget build(BuildContext context) {
+            return new _EffectiveTickerMode(
+                enabled: enabled && TickerMode.of(context),
+                child: child
+            );
+        }
+        public override void debugFillProperties(DiagnosticPropertiesBuilder properties) {
+            base.debugFillProperties(properties);
+            properties.add(new FlagProperty("requested mode", value: enabled, ifTrue: "enabled", ifFalse: "disabled", showName: true));
+        }
+    }
+    public class _EffectiveTickerMode : InheritedWidget { 
+        public _EffectiveTickerMode(
+            bool enabled,
+            Key key = null,
+            Widget child = null) : 
+            base(key: key, child: child) {
+            D.assert(enabled != null);
+            this.enabled = enabled;
+        public readonly bool enabled;
-            properties.add(new FlagProperty("mode", value: enabled, ifTrue: "enabled", ifFalse: "disabled",
-                showName: true));
+            properties.add(new FlagProperty("effective mode", value: enabled, ifTrue: "enabled", ifFalse: "disabled", showName: true));
+        }
+
+        public override bool updateShouldNotify(InheritedWidget oldWidget) {
+            oldWidget = (_EffectiveTickerMode) oldWidget;
+            return enabled != ((_EffectiveTickerMode) oldWidget).enabled;
+
 
     public abstract class SingleTickerProviderStateMixin<T> : State<T>, TickerProvider where T : StatefulWidget {
         Ticker _ticker;

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

 
         public override void initState() {
             _currentTween = widget.tween;
-            _currentTween.begin ??= _currentTween.end;
+            if (_currentTween.begin == null) {
+                _currentTween.begin = _currentTween.end;
+            }
+
+            
             base.initState();
             if (_currentTween.begin.Equals( _currentTween.end)) {
                 controller.forward();