code: public PaintableGroup getGroup(RenderGroup group) {
  		switch (group) {
  			case RASTER:
  				return rasterGroup;
  			case VECTOR:
  				return vectorGroup;
  			case WORLD:
  				return worldGroup;
  			case SCREEN:
  			default:
  				return screenGroup;
  		}
  	}
docs: Return the Object that represents one the default RenderGroups in the DOM tree when drawing.
  
  @param group
  The general group definition (RenderGroup.SCREEN, RenderGroup.WORLD, ...)
  @return paintable group