title: How to Add Listeners to RadioButtons in EXTJS4
body: <p>I'm very new to ExtJs and I wanted to display an alert box on clicking one of the radio buttons, but it does not seem to work. Could anyone guide me through this step? The listener does not seem to work.</p>
  
  <pre class="lang-js prettyprint-override"><code>{
      xtype: 'radiogroup',
      fieldLabel: 'Does Nodes have DHCP IP Scheme?',
      id:'dhcpRadio',
      columns: [50, 50],
      // Arrange radio buttons into two columns, distributed vertically
      columns: 2,
      vertical: true,
      items: [{
      boxLabel: 'Yes',
          name: 'rb', 
          inputValue: 'yes',
          listeners: {
              check: function(rb,value){
                  if(value=='yes') 
                      alert('yes');
                  else alert('no');
              }
          }
      },{
          boxLabel: 'No',
          name: 'rb',
          inputValue: 'no',
          checked: true
      }]
  }
  </code></pre>