title: Pixi is not changing position when click on sprite
body: <p>I was trying to create a sample pixi application. Where I had an image, when user clicks on the image, it should move its position.</p>
  
  <pre><code>var canvasWidth = window.innerWidth;
  var canvasHight = window.innerHeight
  
  var renderer = PIXI.autoDetectRenderer(canvasWidth, canvasHight);
  document.body.appendChild(renderer.view);
  var stage = new PIXI.Container();
  
  PIXI.loader
      .add('images/sample.png')
      .add('images/background.jpg')
      .load(setup);
  
  function setup() {
      var backGround = new PIXI.Sprite(
          PIXI.loader.resources["images/background.jpg"].texture);
      var steve = new PIXI.Sprite(
          PIXI.loader.resources["images/sample.png"].texture);
      backGround.hieght = canvasHight;
      backGround.width = canvasWidth;
      setPropertiesToSteve(steve);
      stage.addChild(backGround);
      stage.addChild(steve);
      renderer.render(stage);
  }
  
  // Function just to set properties for steve
  function setPropertiesToSteve(steve) {
      steve.interactive = true;
      steve.position.x = canvasWidth/2;
      steve.position.x = canvasWidth/4;
      steve.on('pointerdown',function(){
          steve.position.x = steve.position.x + 10;
      });
  }
  </code></pre>
  
  <p>But when I click on the object nothing happening. I am very much new to pixijs.SO don't know how to handle this.  </p>