Fixes broken layer link in embeds

packages/zefyr/lib/src/widgets/common.dart

   @override
   Widget build(BuildContext context) {
     final scope = ZefyrScope.of(context);
-
     if (scope.isEditable) {
       ensureVisible(context, scope);
     }
       content = buildEmbed(context, scope);
     } else {
       assert(widget.style != null);
-
-      final text = ZefyrRichText(
+      content = ZefyrRichText(
         node: widget.node,
         text: buildText(context),
       );
-      if (scope.isEditable) {
-        content = EditableBox(
-          child: text,
-          node: widget.node,
-          layerLink: _link,
-          renderContext: scope.renderContext,
-          showCursor: scope.showCursor,
-          selection: scope.selection,
-          selectionColor: theme.selectionColor,
-        );
-        content = CompositedTransformTarget(link: _link, child: content);
-      } else {
-        content = text;
-      }
+    }
+
+    if (scope.isEditable) {
+      content = EditableBox(
+        child: content,
+        node: widget.node,
+        layerLink: _link,
+        renderContext: scope.renderContext,
+        showCursor: scope.showCursor,
+        selection: scope.selection,
+        selectionColor: theme.selectionColor,
+      );
+      content = CompositedTransformTarget(link: _link, child: content);
     }
 
     if (widget.padding != null) {
   }
 
   Widget buildEmbed(BuildContext context, ZefyrScope scope) {
-    final theme = ZefyrTheme.of(context);
-
     EmbedNode node = widget.node.children.single;
     EmbedAttribute embed = node.style.get(NotusAttribute.embed);
 
-    Widget result;
     if (embed.type == EmbedType.horizontalRule) {
-      result = ZefyrHorizontalRule(node: node);
+      return ZefyrHorizontalRule(node: node);
     } else if (embed.type == EmbedType.image) {
-      result = ZefyrImage(node: node, delegate: scope.imageDelegate);
+      return ZefyrImage(node: node, delegate: scope.imageDelegate);
     } else {
       throw new UnimplementedError('Unimplemented embed type ${embed.type}');
     }
-
-    if (!scope.isEditable) {
-      return result;
-    }
-
-    return new EditableBox(
-      child: result,
-      node: widget.node,
-      layerLink: _link,
-      renderContext: scope.renderContext,
-      showCursor: scope.showCursor,
-      selection: scope.selection,
-      selectionColor: theme.selectionColor,
-    );
   }
 }

packages/zefyr/lib/src/widgets/editable_box.dart

   set showCursor(ValueNotifier<bool> value) {
     assert(value != null);
     if (_showCursor == value) return;
+    // TODO: only mark to repaint if cursor is collapsed and inside this box.
     if (attached) _showCursor.removeListener(markNeedsPaint);
     _showCursor = value;
     if (attached) _showCursor.addListener(markNeedsPaint);

packages/zefyr/lib/src/widgets/scope.dart

+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:notus/notus.dart';
 
     }
     notifyListeners();
   }
+
+  @override
+  String toString() {
+    return '$ZefyrScope#${shortHash(this)}';
+  }
 }
 
 class ZefyrScopeAccess extends InheritedWidget {

packages/zefyr/lib/src/widgets/selection.dart

 
 import 'controller.dart';
 import 'editable_box.dart';
+import 'render_context.dart';
 import 'scope.dart';
 
 RenderEditableBox _getEditableBox(HitTestResult result) {
 
     RenderEditableProxyBox box = _getEditableBox(result);
     if (box == null) {
-      final scope = ZefyrScope.of(context);
-      box = scope.renderContext.closestBoxForGlobalPoint(globalPoint);
+      box = _editor.renderContext.closestBoxForGlobalPoint(globalPoint);
     }
     if (box == null) return null;
 
 
   @override
   Widget build(BuildContext context) {
-    final scope = ZefyrScope.of(context);
     if (selection == null ||
         selection.isCollapsed ||
         widget.controls == null ||
-        scope.focusOwner != FocusOwner.editor) {
+        _scope.focusOwner != FocusOwner.editor) {
       return new Container();
     }
-    final block = scope.renderContext.boxForTextOffset(documentOffset);
+    final block = _scope.renderContext.boxForTextOffset(documentOffset);
     final position = getPosition(block);
     Widget handle;
     if (position == null) {
   Offset _dragPosition;
 
   void _handleScopeChange() {
-    setState(() {
-      _selection = _scope.selection;
-    });
+    if (_selection != _scope.selection) {
+      setState(() {
+        _selection = _scope.selection;
+      });
+    }
   }
 
   void _handleDragStart(DragStartDetails details) {
   void _handleDragUpdate(DragUpdateDetails details) {
     _dragPosition += details.delta;
     final globalPoint = _dragPosition;
-    final scope = ZefyrScope.of(context);
-    final paragraph = scope.renderContext.boxForGlobalPoint(globalPoint);
+    final paragraph = _scope.renderContext.boxForGlobalPoint(globalPoint);
     if (paragraph == null) {
       return;
     }
     }
 
     if (newSelection != _selection) {
-      scope.updateSelection(newSelection, source: ChangeSource.local);
+      _scope.updateSelection(newSelection, source: ChangeSource.local);
     }
   }
 }
       return Container();
     }
     final boxes = block.getEndpointsForSelection(selection);
-
     // Find the horizontal midpoint, just above the selected text.
     final Offset midpoint = new Offset(
       (boxes.length == 1)
       block.localToGlobal(Offset.zero),
       block.localToGlobal(block.size.bottomRight(Offset.zero)),
     );
-
     final toolbar = widget.controls
         .buildToolbar(context, editingRegion, midpoint, widget.delegate);
     return new CompositedTransformFollower(