title: Enable/disable checkbox in extjs
body: <p>I want to enable or disable checkboxes in EXTJS</p>
  
  <pre><code> dockedItems: [{
          xtype: 'toolbar',
          dock: 'top',
          items: [{
              xtype: 'radiofield',
              id: 'all',
              name: 'show',
              boxLabel: 'All',
              checked: true,
              inputValue: 'all'
          }, {
              xtype: 'radiofield',
              id: 'online',
              name: 'show',
              boxLabel: 'Online',
              inputValue: 'online'
          }, {
              xtype: 'radiofield',
              id: 'offline',
              name: 'show',
              boxLabel: 'Offline',
              inputValue: 'offline'
          }, {
              xtype: 'checkboxfield',
              id: 'cb1',
              boxLabel: 'Sometimes',
              checked: true,
              inputValue: 'sometimes'
          }, {
              xtype: 'checkboxfield',
              id: 'cb2',
              boxLabel: 'Always',
              checked: true,
              inputValue: 'always'
          }],
          listeners: {
              change: function (field, newValue, oldValue) {
                  var value = newValue.show;
                  if (value == 'all') {
                      var cb1 = Ext.getCmp('cb1');
                      var cb2 = Ext.getCmp('cb2');
  
                      cb1.disable();
                      cb2.disable();
                  }
                  if (value == 'online') {
                      var cb1 = Ext.getCmp('cb1');
                      var cb2 = Ext.getCmp('cb2');
  
                      cb1.disable();
                      cb2.disable();
                  }
                  if (value == 'offline') {
  
                      var cb1 = Ext.getCmp('cb1');
                      var cb2 = Ext.getCmp('cb2');
  
                      cb1.enable();
                      cb2.enable();
  
                  }
  
              }
          }
      }]
  </code></pre>
  
  <p>How can I enable these checkboxes? They should be enabled when the user selects the offline option and disabled when the user selects other option.</p>
  
  <p>Thanks for your help!</p>