title: how to callback after store.sync are failure?
body: <pre><code>    function onButtonClick(){
                 var grid = Ext.getCmp('mygridpanel')
                 var row = grid.getSelectionModel().getSelection()[0];
                 var txtVehicleID = Ext.getCmp('txtVehicleID').getValue();
                 var txtPlat_No = Ext.getCmp('txtPlat_No').getValue();
                 console.log(txtVehicleID);
  
                  var record = UserStore.findRecord('_id', txtVehicleID);
                  record.set('_id', txtVehicleID);
                  record.set('Plat_No',txtPlat_No);
  
                  UserStore.sync({
                      success: function(batch) {
                                  Ext.MessageBox.show({
                                      title: "Information",
                                      msg: batch.operations[0].request.scope.reader.jsonData["message"],
                                      icon: Ext.MessageBox.INFO,
                                      buttons: Ext.MessageBox.OK,
                                      fn: function(buttonId) {
                                          if (buttonId === "ok") {
                                              EditWin.close();
                                          }
                                      }
                                  });  
                      },
                          failure: function(batch){
                                         Ext.MessageBox.show({
                                      title: "Error",
                                      msg: batch.operations[0].request.scope.reader.jsonData["message"],
                                      icon: Ext.MessageBox.ERROR,
                                      buttons: Ext.MessageBox.OK,
                                      fn: function(buttonId) {
                                          if (buttonId === "ok") {
                                                  // Call back at here
                                      EditWin.close();
                                          }
                                      }
                          });  
  
                      }
                  });
                  //console.log("clicked");
      }
  </code></pre>
  
  <p>how to callback after store.sync are failure ?</p>