@Override
	public void propertyChange(PropertyChangeEvent event) {
		String property = event.getPropertyName();
		if (property.equals(Global.DRAG_EVENT) && isVisible()) { //don't have to move invisible markers
			handleDrag(event.getOldValue(), event.getNewValue());
		} else if (property.startsWith(Global.ZOOM)){
			handleZoom();
		}
	}