anchor.diff:        mainCanvas.context2D.drawImage(nextLayer, 0, 0);
         currentContext.clearRect(0, 0, 640, 480);
       }
  +
  +    drawPoints.clear();
     }
   }
  
positive.code:     chatList.children.removeAt(0);
    }
  
    static void _drawPoint(num x, num y, num size, String color) {
      nextCanvasLayer();
  
      currentContext
        ..beginPath()
        ..arc(x, y, size / 2, 0, 2 * PI)
        ..closePath()
        ..fillStyle = color
        ..fill();
    }
  
    static void _drawLine(
        num x1, num y1, num x2, num y2, num size, String color) {
      currentContext
        ..beginPath()
        ..moveTo(x1, y1)
        ..lineTo(x2, y2)
        ..closePath()
        ..lineWidth = size
        ..strokeStyle = color
        ..lineCap = 'round'
        ..lineJoin = 'round'
        ..stroke();
    }
  
    static void _clearDrawing() {
  
negative.code: 
    static ClientWebSocket client;
  
    static List<Point> drawPoints = [];
    static Brush brush = new Brush();
  
    static init(ClientWebSocket _client) {
      client = _client;
  
      Timer timer;
  
      client
  