title: drawing custom lines on highchart graph
body: <p>I have recently been working with the highchart api to plot some data on a website, and I have need to be able to add a custom vertical "line" to symbolise something happening for example a press release.</p>
  
  <p>I have thought about adding a column element to the chart as a seperate series but this is less than ideal.</p>
  
  <p>if anyone has any ideas that would be awesome</p>
  
  <p>thanks</p>