title: I can't add/override a combo listeners
body: <p>I have 2 js files, one that defined the combo, the second file is a window that calls combo declaration..<br>
  in window file, I try to add or override some listener, but the listener does not work</p>
  
  <p>here is the combo: </p>
  
  <pre><code>App.form = function() {
      return {
          ComboCouch: function(config) {  
              var store = new Ext.data.JsonStore({
                  autoDestroy: true,
                  autoLoad:(config.autoLoad==true)?true:false,
                  storeId :config.storeId,
                  url: config.couchView,
                  root: 'rows',
                  fields: ['key', 'value']
              });
              var combo = new Ext.form.ComboBox({
                  store: store,
                  valueField: "key",
                  displayField: "value",
                  typeAhead: true,
                  mode: 'local',
                  forceSelection: true,
                  triggerAction: 'all',
                  selectOnFocus:true/*, this when i try to override
                  listeners: {
                      'expand': function(c) {
                          c.store.reload();
                      }
                  }*/
              });
              Ext.apply(combo,config);
              return combo;
          }
      };
  }();
  
  Ext.reg("appcombocouch",App.form.ComboCouch);
  </code></pre>
  
  <p>and this my window:</p>
  
  <pre><code>App.Download = function() {
      return {
          dialog : null,
          init : function() {
              this.baseUrl = '/';
              this.whoami = null;
  
              if (!App.urlRewrite) this.baseUrl = '/' + App.database + this.baseUrl;
  
              if (App.Privilage.length==2 &amp;&amp; (App.Privilage =="00" || App.Privilage &lt;=0)) this.whoami = "Admin";
              else if (App.Privilage.length==2 &amp;&amp; (App.Privilage !="00" || App.Privilage &gt;0)) this.whoami = "Prop";
              else this.whoami = "Kab";
          },
  
          createItems : function(){
              var items = new Array(); 
  
              if(this.whoami == "Admin"){
                  items.push({
                      fieldLabel: 'Pilih Provinsi',
                      title : 'Provinsi',
                      xtype: 'appcombocouch',
                      couchView : 'r_propinsi',
                      width:250,
                      name : 'kd_prop',
                      autoLoad : true,
                      scope : this,
                      //this, i want to add/pverride listener
                      listeners: {
                          'expand': function(c) {
                              Ext.Msg.alert("test","do you see me");// this alert never show, when the combo expanded
                              c.store.reload();
                          }
                      }
                  });
              }
  
              var form = new Ext.form.FormPanel({
                  labelWidth:110,
                  //url:'php/download.php',
                  frame:true,
                  autoHeight:true,
                  title:'Download DBF', 
                  defaultType:'textfield',
                  monitorValid:true,
                  items : [items]
              })
              return form;
          },      
  
          show : function() {
              if (!this.dialog) {
                  this.dialog = new Ext.Window({
                      items: [this.createItems()],
                  });
              }
              this.dialog.show();
          }
      };
  }();
  
  Ext.onReady(App.Download.init, App.Download, true);
  </code></pre>