anchor.diff:  
     void _handleSubmitted(String text) {
       _textController.clear();
  +    setState(() {
  +      _isComposing = false;
  +    });
       ChatMessage message = new ChatMessage(
         text: text,
         animationController: new AnimationController(
  
positive.code:             new Flexible(
                child: new TextField(
                  controller: _textController,
                  onChanged: (String text)  {                //new
                    setState(() {
                      _isComposing = text.length > 0;
                    });
  
negative.code:           ),
           ]
         ),
         decoration: Theme.of(context).platform == TargetPlatform.iOS ? new BoxDecoration(border: new Border(top: new BorderSide(color: Colors.grey[200]))) : null),
     );
    }
  }
  