@Override
	public void mouseDragged(MouseEvent evt) {

		Point p;
		if (evt.getSource().equals(slider)) {
			p = new Point (truncX(slider.getLocation().x + (evt.getX() - startPointX)), 3);
			Date d = xToDate ((int)p.getX());
			Calendar c = Calendar.getInstance();
			c.setTime(d);
			if (c.get(Calendar.MINUTE) % 15 == 0) {
				trip.setTripStartTime(d);
				startTimeSpinner.setValue(d);
				slider.setLocation(p);
			}
		}
	}