title: How to override tick() to lower FPS in multiple Stages
body: <p>Assuming we have 2 Stages and <code>Ticker.setFPS(30)</code>, how can i override the ticker for the second stage to have let's say 15fps?</p>
  
  <pre class="lang-js prettyprint-override"><code>// Targeting 30fps
  Stage['GUI'] = new createjs.Stage(gui_canvas);
  createjs.Ticker.useRAF = true;
  createjs.Ticker.setFPS(30);
  createjs.Ticker.addEventListener('tick', Stage['GUI']);
  // Targeting 15fps
  Stage['Background'] = new createjs.Stage(bg_canvas);
  /* Overriding ticker goes here */
  createjs.Ticker.addEventListener('tick', Stage['Background']);
  </code></pre>
  
  <p><strong>solved using markE's solution</strong></p>
  
  <pre class="lang-js prettyprint-override"><code>stage['background'] = new createjs.Stage(bg_canvas);
  
  var delay = 3;
  var ticker = function(params){
    if(delay===0){
      delay = -1;
      stage['background'].update();
      delay = 3;
    }
    delay--;
  };
  createjs.Ticker.addEventListener('tick', ticker);
  </code></pre>
  
  <p><strong>another solution for getting targeted FPS</strong></p>
  
  <pre class="lang-js prettyprint-override"><code>stage['background'] = new createjs.Stage(bg_canvas);
  
  var timestamp = new Date().getTime();
  var ticker = function(){
    var now = new Date().getTime();
    if ((now - timestamp) &gt; (1000/15)){
        stage['background'].update();
        timestamp = new Date().getTime();
    }
  };
  createjs.Ticker.addEventListener('tick', ticker);
  </code></pre>