title: How to use HighStock's tickPositioner to set tick at end of month?
body: <p><a href="http://highcharts.uservoice.com/forums/55896-highcharts-javascript-api/suggestions/4959862-adjusting-the-automatic-tickplacement-on-a-datetim" rel="nofollow">This highcharts admin response</a> explains this is not natively possible: </p>
  
  <blockquote>
    <p>There's no option for using the last date of the month, but you can
    create your own tickPositioner callback</p>
  </blockquote>
  
  <p>I've followed the advice, however nothing seems to change regardless of the tickPositioner function! <strong><a href="http://jsfiddle.net/2dnxqs2f/3/" rel="nofollow">I've created an isolated demo of the issue here.</a></strong> [It's just <a href="http://www.highcharts.com/stock/demo/basic-line" rel="nofollow">this example</a> with the tick positioner added.]</p>
  
  <p>In the jsFiddle example you can see my tickPositioner below. I subtract one day (<code>60*60*24*1000</code>) 15 times (<code>*15</code>).  Fifteen is random just to show there's not affect.  </p>
  
  <pre><code>        xAxis:{
              //LOOK HERE!
              tickPositioner:function(){
                  return _.forEach(this.tickPositions, function(date){                         
                      console.log('date',date, new Date(date), new Date(date - 60*60*24*1000*15));
                      //return date;   //uncomment to show orginal dates                     
                      return (date - 60*60*24*1000*15);
                  });
              //LOOK HERE!
              }
          },
  </code></pre>
  
  <hr>
  
  <p>Extra notes: </p>
  
  <p>I can tell the tickpositioner is doing something because I can:</p>
  
  <ul>
  <li>remove the ticks altogether if the function is setup incorrectly</li>
  <li>oddly format the the dates if the dates are incorrect</li>
  <li>not change the date ticks at all if everything is correctly set up.  </li>
  </ul>
  
  <p><strong>I suspect</strong> there is something going on with the formatting of the dates and minimum tick intervals.  In the official highcharts <a href="http://jsfiddle.net/gh/get/jquery/1.7.2/highslide-software/highcharts.com/tree/master/samples/highcharts/xaxis/tickpositions-tickpositioner/" rel="nofollow">example</a> for tickpositioner there I can see it working, but if you decrease the custom increment they setup you can see a similar issue where there's no affect on the tick positions.</p>