title: extjs hidden panel flicker when slide in on show
body: <p>I need to show a panel on a click event. The panel needs to slide into view on show and it needs to be anchored to the button once shown (the one that has the click event). </p>
  
  <p>The panel config (helpPanel) is as follows:</p>
  
  <pre><code>{
      xtype: 'container',
      autoScroll: true,
      hidden: true,
      floating: true,
      shadow: false,
      listeners: {
          show: function(panel) {
              panel.el.slideIn('r', {
                  easing: 'easeOut',
                  duration: 500
              })
          }
      }
  }
  </code></pre>
  
  <p>The panel is shown in the button's click event handler:</p>
  
  <pre><code>helpPanel.showBy(helpButton, 'tr-br');
  </code></pre>
  
  <p>It works fine, except there is a quick / small flicker before the panel is shown. A bit like the panel is shown and then it is hidden before sliding into the view again.</p>
  
  <p>Is this the right way to implement a slide-in show?</p>
  
  <p>Thank you</p>
  
  <p>Fiddle:
  <a href="http://jsfiddle.net/cs2014/nwvahc60/" rel="nofollow"><a href="http://jsfiddle.net/cs2014/nwvahc60/" rel="nofollow">http://jsfiddle.net/cs2014/nwvahc60/</a></a></p>