title: Line chart is showing under bar in combochart in chartjs
body: <p>I am using combo chart using chart.js in my website.</p>
  
  <p>The problem I am facing is the line disappears when it meets the bar. I think it is because the line chart is showing below the bar chart.
  <a href="https://i.stack.imgur.com/IFHrm.png" rel="noreferrer"><img src="https://i.stack.imgur.com/IFHrm.png" alt="enter image description here"></a></p>
  
  <p>PFB the code I used.</p>
  
  <p>var PCTCtx = document.getElementById("pctdiv").getContext("2d");</p>
  
  <pre><code>    PCTChart = new Chart(PCTCtx, {
          type: 'bar',
          data: {
              datasets: [{
                  label: 'Bar Dataset',
                  data: [100, 70, 60, 40],
                  backgroundColor: ['red', 'red', 'red', 'red']
              }, {
                  label: 'Line Dataset',
                  data: [50, 50, 50, 50],
                  fill: false,
                  backgroundColor: ['#000000', '#000000', '#000000', '#000000'],
                  // Changes this dataset to become a line
                  type: 'line'
              }],
              labels: ['January', 'February', 'March', 'April']
          },
          options:  {
                      scales: {
                          yAxes: [{
                              ticks: {
                                  beginAtZero: true
                              },
                              gridLines: {
                                  display: false
                              }
                          }],
                          xAxes: [{
                              barThickness: 35,
                              gridLines: {
                                  display: false
                              }
                          }]
                      }
                  }
      });
      PCTChart.data.datasets[1].borderColor = '#000000';
      PCTChart.update();
  </code></pre>
  
  <p>I need the line to show on the bar chart.</p>
  
  <p>I have created a jsfiddle for the same <a href="https://jsfiddle.net/o7wL0j6d/4/" rel="noreferrer">here</a></p>
  
  <p>Any help would be appreciable.</p>