code: public void unregisterPainter(Painter painter) {
  		String className = painter.getPaintableClassName();
  		if (painters.containsKey(className)) {
  			List<Painter> list = painters.remove(className);
  			if (list.size() > 1) {
  				list.remove(painter);
  				painters.put(className, list);
  			}
  		}
  	}
docs: Unregister an existing painter from this visitor.
  
  @param painter
  The painter itself.