anchor.diff:    //
     // If it has a parent, we should temporarily hide it.
     void _showModalOverlay({bool temporary = false}) {
  -    _saveFocus();
       if (!temporary) {
  +      _saveFocus();
         if (_stack != null) {
           _stack.onModalOpened(this);
         } else if (_parentModal != null) {
  
positive.code: import 'package:angular_components/src/laminate/components/modal/modal_controller_directive.dart';
  import 'package:angular_components/laminate/overlay/overlay.dart';
  import 'package:angular_components/model/action/async_action.dart';
  import 'package:angular_components/utils/disposer/disposer.dart';
  
  /// May be added to DI to enforce that a single [Modal] is visible at a time.
  
negative.code:   Future<bool> _pendingOpen;
    Future<bool> _pendingClose;
  
    ModalComponent(OverlayService overlayService, this._element, this._domService,
        @Optional() @SkipSelf() this._parentModal, @Optional() this._stack) {
      _createdOverlayRef(
          overlayService.createOverlayRefSync(OverlayState.Dialog));
  