title: ChartJS v2 - Keep tooltip open when user click on a point of a multiple lines chart
body: <p>I use chartJS v2. </p>
  
  <p>I try to keep tooltip open when user click on a point of a multiple lines chart. The tooltip must contains the data for each lines for one abscissa value.
  I wrote a chartJS plugin to do it and it works but it displays only the data for one line.</p>
  
  <p><strong>Here is the fiddle:</strong></p>
  
  <p><a href="https://jsfiddle.net/bencarbon/jrpLh8pa/" rel="nofollow noreferrer">https://jsfiddle.net/bencarbon/jrpLh8pa/</a></p>
  
  <p>Here is the plugin:</p>
  
  <pre><code>    var keepTooltipOpenPlugin = {
  
        beforeRender: function(chart) {
  
      // We are looking for bubble which owns "keepTooltipOpen" parameter.
          var datasets = chart.data.datasets;
          chart.pluginTooltips = [];
          for (i = 0; i &lt; datasets.length; i++) {
            for (j = 0; j &lt; datasets[i].data.length; j++) {
              if (datasets[i].data[j].keepTooltipOpen &amp;&amp; !chart.getDatasetMeta(i).hidden) {
              //When we find one, we are pushing all informations to create the tooltip.
                chart.pluginTooltips.push(new Chart.Tooltip({
                  _chart: chart.chart,
                  _chartInstance: chart,
                  _data: chart.data,
                  _options: chart.options.tooltips,
                  _active: [chart.getDatasetMeta(i).data[j]]
                }, chart));
              }
            }
          }
        }, // end beforeRender
  
        afterDatasetsDraw: function(chart, easing) {
  
            // Draw tooltips
            Chart.helpers.each(chart.pluginTooltips, function(tooltip) {
              tooltip.initialize();
              tooltip.update();
              tooltip.pivot();
              tooltip.transition(easing).draw();
            });
  
  
          } // end afterDatasetsDraw
      }
  
      Chart.pluginService.register(keepTooltipOpenPlugin);
  </code></pre>
  
  <p>I use it in this way:</p>
  
  <pre><code>function handleClick(evt) {
      var activeElement = myLineChart.getElementAtEvent(evt);
      if(activeElement.length&gt;0){
          var values = myLineChart.data.datasets[activeElement[0]._datasetIndex].data[activeElement[0]._index];
          if(values.keepTooltipOpen)
              values.keepTooltipOpen = false;
          else
            values.keepTooltipOpen = true;
      }
  };
  </code></pre>
  
  <p><strong>How should I modify my plugin to display the data for each lines in the tooltip??</strong></p>
  
  <p>Thanks</p>