title: Chart.js v2.0: Tooltip only for one dataset
body: <p>I have graph whit this 3 datasets:</p>
  
  <pre class="lang-js prettyprint-override"><code>this.myChart = new Chart(this.ctx, {
    type: 'bar',
    data: {
      labels: labels,
      datasets: [
        { type: 'line', data: data3 },
        { type: 'bar', data: data1, backgroundColor: "#3EAFD5" },
        { type: 'bar', data: data2, backgroundColor: "#D24B47" }
      ]
    }
  }
  </code></pre>
  
  <p>How can I do to show tooltip only for first dataset (type: 'line')?</p>