title: Tree panel in extjs 5 not rendering
body: <p>The tree panel doesn't get rendered
  Code is :</p>
  
  <pre><code>Ext.define('mainPanel',{
      extend:'Ext.form.Panel',
      layout: {
      type: 'hbox',
      align: 'stretch'
      },
      width:'100%',
      height:'100%',
      title:'SQL',
      initComponent:function()
      {
          var tableDiv = this.getTableColumn();
          var analyzerDiv = this.getAnalyzerColumn();
          var fieldDiv = this.getfieldColumn();
          this.items=[tableDiv,analyzerDiv,fieldDiv];
          this.callParent();
      },
      getTableColumn:function()
      {   
          var TableColumn = Ext.create('Ext.tree.Panel',{
                              title:'Tables',
                              width:'20%',
                              heigth:'100%',
                              layout: 'fit',
                              border:true,
                              store: tableTreeStore,
                              rootVisible: false
  
                          });
          return TableColumn;
      }
  </code></pre>
  
  <p>Pls let me know where i am going wrong. Thanks in advance
  the error i get is </p>
  
  <p>TypeError: c is not a constructor
  return new c(a[0])</p>