title: Customizing tooltip on Google Timeline Chart
body: <p>I created a Google Timeline Chart to see my musical listening history. It looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/auKMw.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/auKMw.png" alt="enter image description here"></a></p>
  
  <p>I want to remove duration part from the tooltip, but couldn't find any option for it. I tried adding these lines:</p>
  
  <pre><code>dataTable.addColumn({type: 'string', role:'tooltip'});
  </code></pre>
  
  <p>and a row in my <code>dataTable.addRows([])</code> function looks like this:</p>
  
  <pre><code>['25 August', 'Kasabian - La Fee Verte', new Date(2016,01,01, 13,37,32), new Date(2016,01,01, 13,43,19), 'tooltip example'],
  </code></pre>
  
  <p>but it still shows the same tooltip as in the image. I actually want to show <code>Kasabian - La Fee Verte and 25 August: 1:37 pm - 1:43 pm</code> just like in the image, but I want to remove duration.</p>