title: using relayEvent
body: <p>I have simple DelButton class:</p>
  
  <pre>
  DelButton = Ext.extend(Ext.Button, {
      ,disabled: false
      ,listeners: {
          ,selectionchange: function() {
              alert('!!!!');
          }
      ,initComponent:function() {
          this.relayEvents(this.grid.getSelectionModel(), ['selectionchange']);
          DelButton.superclass.initComponent.call(this);
      }
  });
  </pre>
  
  <p><pre>
  buildTBar: function(config) {
      config.tbar = {}
      config.tbar.push(new DelButton({grid:this }))
  }
  </pre>,
  <pre>
  buildConfig:function(config) {
      this.buildTBar(config)
  }
  </pre>,</p>
  
  <pre>
  AbstractEditorGridPanel = Ext.extend(Ext.grid.EditorGridPanel, {
      initComponent:function() {
          var config = {
              defaults:{border:true, autoHeight:false }
          };
          this.buildConfig(config);
          Ext.apply(this, Ext.apply(this.initialConfig, config));
          AbstractEditorGridPanel.superclass.initComponent.call(this);
  
      }
  </pre>
  
  <p>Why relayEvent don't work in this case ? ( this.grid.getSelectionModel is exists )</p>