title: Ext Js running a function for a Yes No Msg box
body: <p>This could be a very stupid and obvious answer but I couldn't find any answer to this( a particular example by a user on Sencha Docs also didn't <a href="http://docs-origin.sencha.com/extjs/4.2.1/#!/api/Ext.window.MessageBox" rel="nofollow">work</a> ,the one in the comments section). </p>
  
  <p>I want to create a popup which will take in  yes no or cancel using Ext Js. In ExtJs 3, it is written as      </p>
  
  <pre><code>              Ext.onReady(function() {
                    Ext.Msg.show({
                        title: 'Milton',
                        msg: 'Have you seen my stapler?',
                        buttons: {
                        yes: true,
                         no: true,
                        cancel: true
                       },
                       icon: 'milton-icon',
                       fn: function(btn) {
                       Ext.Msg.alert('You Clicked', btn);
                             }
                         });
                       }); 
  </code></pre>
  
  <p>I want to do the same thing in Ext 4.2 but its not working </p>
  
  <pre><code>                 Ext.onReady(function() {
                       Ext.Msg.show({
                                 title: 'Milton',
                                 msg: 'Have you seen my stapler?',
                                 buttons: Ext.Msg.YESNOCANCEL,
                                 icon: Ext.Msg.ERROR,
                                 fn: function(btn) {
                                 Ext.Msg.alert('You clicked',btn);
                                   }
                              });
                       });
  </code></pre>
  
  <p>The function doesn't work at all. I tried them on Jsbin and Jsfiddle using SDN but they don't work. Here is the link to the <a href="http://jsbin.com/IzaRafI/1/edit" rel="nofollow">JSBin</a> code if it helps. </p>