anchor.diff:      this.height,
       this.padding,
       this.opacity,
  -    this.performance,
  +    this.animation,
       this.target,
       this.verticalOffset,
       this.screenEdgeMargin,
  
positive.code:     assert(_entry != null);
      _timer?.cancel();
      _timer = null;
      _performance.reverse();
    }
  
    void deactivate() {
  
negative.code:   }
  
    void resetShowTimer() {
      assert(_controller.status == PerformanceStatus.completed);
      assert(_entry != null);
      _timer = new Timer(config.showDuration, hideTooltip);
    }
  