anchor.diff:          // Erzeugt ein Z Tetris Stein in der Farbe rot
           _tempColor = #red;
           temp = [
  -          { 'row' : height ~/ 2,       'col' : width ~/ 2 - 1  },
  +          {'row' : height ~/ 2,       'col' : width ~/ 2 - 1  },
             { 'row' : height ~/ 2,       'col' : width ~/ 2      },
             { 'row' : height ~/ 2 + 1,   'col' : width ~/ 2      },
             { 'row' : height ~/ 2 + 1,   'col' : width ~/ 2 + 1  }
  
positive.code: 
    /**
     * Drehen des Tetris Steins um 90 Grad
     * Y Koordinate: row
     * x Koordinate: col
     * Rotationsformal für 90 Grad:
     * x' = x * cos(90) - y * sin(90)
     * y' = x * sin(90) + y * cos(90)
     */
    void rotate(){
      var _rotate = [
        { 'row' : ~(_stone.elementAt(0)['col'] * sin(90) + _stone.elementAt(0)['row'] * cos(90)),  'col' : ~(_stone.elementAt(0)['col'] * cos(90) - _stone.elementAt(0)['row'] * sin(90)) },
        { 'row' : ~(_stone.elementAt(1)['col'] * sin(90) + _stone.elementAt(1)['row'] * cos(90)),  'col' : ~(_stone.elementAt(1)['col'] * cos(90) - _stone.elementAt(1)['row'] * sin(90)) },
        { 'row' : ~(_stone.elementAt(2)['col'] * sin(90) + _stone.elementAt(2)['row'] * cos(90)),  'col' : ~(_stone.elementAt(2)['col'] * cos(90) - _stone.elementAt(2)['row'] * sin(90)) },
        { 'row' : ~(_stone.elementAt(3)['col'] * sin(90) + _stone.elementAt(3)['row'] * cos(90)),  'col' : ~(_stone.elementAt(3)['col'] * cos(90) - _stone.elementAt(3)['row'] * sin(90)) }
      ];
  
      _stone = _rotate;
  
negative.code:    */
    void stop() { _gamestate = #stopped; }
  
  
    /**
     * Konstruktor um ein neues Tetris Spiel zu erzeugen
  