textfield click 이벤트

            {xtype: 'textfield',    id:'vendor_name',  x: 230, y: 185, width: 120, value: '',
             listeners: {        
                 afterrender: function( field ) {
                     field.getEl().on('click', function( event, el ) {
                         alert('aaa');
                     });        
                  }    
             }
            }