@Override
        public void handle(MouseEvent me){
            if(me.getSceneY() >= 200 && me.getSceneX() > 0 
                    && me.getSceneX() < 1000 && me.getSceneY() < 1000){
                line_pendulum.setStartX(me.getSceneX());
                line_pendulum.setStartY(me.getSceneY());
                circle_pendulum.setCenterX(line_pendulum.getStartX());
                circle_pendulum.setCenterY(line_pendulum.getStartY());
                lengthTextField.setText(df_2.
                        format(Math.sqrt(Math.pow(line_pendulum.getStartX()
                        -line_pendulum.getEndX(),2)+Math.pow(line_pendulum.getStartY()
                        -line_pendulum.getEndY(),2))));              
            }           
        }