public void vrule(long timestamp,Paint color,String legend,BasicStroke stroke){
  LegendText legendText=new LegendText(color,legend);
  comments.add(legendText);
  plotElements.add(new VRule(timestamp,color,legendText,stroke));
}

public void vrule ( long timestamp , Paint color , String legend , BasicStroke stroke ) { LegendText legendText = new LegendText ( color , legend ) ; comments . add ( legendText ) ; plotElements . add ( new VRule ( timestamp , color , legendText , stroke ) ) ; }
draws a vertical rule into the graph and optionally adds a legend
