title: How can dynamically change fieldLabel of a Textfield in Ext Js 4?
body: <p>I'm, trying to display textfield label attribute based on a combobox selection.For that i wrote a change listener for combobox and on the listener i,m checking combox value and based on this i have to change fieldLabel property of textfield. Following is the code,</p>
  
  <pre><code>                         textfield:
  
                                   xtype:'textfield',
                                   id:'firstName',
                                   fieldLabel: 'Billing',
                                  name: 'firstName',
                                  maxLength: 30,
                                  enforceMaxLength :true
  </code></pre>
  
  <p>combo-box listener method,</p>
  
  <pre><code>listeners:{
                                      change:function(field, newValue, oldValue)
                                      {   
                                          if(newValue == "billing")
                                          {
                                             var firstName = Ext.getCmp('firstName');     
                                             firstName.fieldLabel = 'Billing'
                                          }
                                          else if(newValue == "shipping"){
                                              var firstName = Ext.getCmp('firstName');
                                               firstName.fieldLabel = 'Shipping'
                                          }
                                          else if(newValue == "recipient"){
                                              var firstName = Ext.getCmp('firstName');
                                               firstName.fieldLabel = 'Receipient'
                                          }
                                      }
  </code></pre>
  
  <p>While debugging this code i can see that the field value is assigning to the fieldLabel attribute but its not reflecting in the UI. Shall i miss something here ?</p>
  
  <p>Thanks.</p>