public void vspan(long start,long end,Paint color,String legend){
  LegendText legendText=new LegendText(color,legend);
  comments.add(legendText);
  plotElements.add(new VSpan(start,end,color,legendText));
}

public void vspan ( long start , long end , Paint color , String legend ) { LegendText legendText = new LegendText ( color , legend ) ; comments . add ( legendText ) ; plotElements . add ( new VSpan ( start , end , color , legendText ) ) ; }
draws a vertical span into the graph and optionally adds a legend .
