title: JqueryFlot inconsistent issue IE8
body: <p>i am using Jquery Flot chart library and i was able to create a Time Line Chart but i have a problem with IE 8.</p>
  
  <p>Basically  the hover event works only for some points.
  Using instead Google Chrome i don't face this issue.</p>
  
  <p>Here the tooltip part:</p>
  
  <pre><code>var previousPoint = null, previousLabel = null;
  var monthNames = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];
  
  $.fn.UseTooltip = function () {
      $(this).bind("plothover", function (event, pos, item) {
          if (item) {         
  
              if ((previousLabel != item.series.label) || (previousPoint != item.dataIndex)) {
                  previousPoint = item.dataIndex;
                  previousLabel = item.series.label;
                  $("#tooltip").remove();
  
                  var x = item.datapoint[0];
                  var y = item.datapoint[1];                
  
                  var color = item.series.color;
                 // var month = new Date(x).getMonth();
  
                      showTooltip(item.pageX,
                              item.pageY,
                              color,
                              "&lt;strong&gt;" +  y + "&lt;/strong&gt;");
  
              }
          } else {
              $("#tooltip").remove();
              previousPoint = null;
          }
      });
  };
  
  function showTooltip(x, y, color, contents) {
      $('&lt;div id="tooltip"&gt;' + contents + '&lt;/div&gt;').css({
          position: 'absolute',
          display: 'none',
          top: y - 40,
          left: x - 120,
          border: '2px solid ' + color,
          padding: '3px',
          'font-size': '9px',
          'border-radius': '5px',
          'background-color': '#fff',
          'font-family': 'Verdana, Arial, Helvetica, Tahoma, sans-serif',
          opacity: 0.9
      }).appendTo("body").fadeIn(200);
  }
  </code></pre>
  
  <p>Could you please help me to find the root cause and a possible solution?</p>
  
  <p>Thanks in advance!</p>