title: How to disable button Ext JS
body: <p>I have a button with id of <code>btnAdd</code> and I want to disable it when some event is fired. The event occurs when some window is closed. So I tried the following code and it does not work.</p>
  
  <pre><code>Ext.create('Ext.window.Window', {
      // Some initialization code goes here...
      listeners: {
         close: function(panel, eOpts){
            Ext.get('btnAdd').disable(); // this does not work;
            Ext.get('btnAdd').setDisabled(); // this one does not either
            Ext.get('btnAdd').disabled = true; // And this one also seems to do nothing
         }
      }
  });
  </code></pre>
  
  <p>How can I do that? This may seem to be pretty easy question but don't judge me bad. I'm quite new to Ext JS. I could not find the answer in the API Documentation either.</p>