title: extjs rowexpander how to expand all
body: <p>I'm using <code>Ext.ux.grid.RowExpander</code></p>
  
  <pre><code>var expander = new Ext.ux.grid.RowExpander({
    tpl : new Ext.Template(
   '&lt;p&gt;{history}&lt;/p&gt;'
   )
  });
  </code></pre>
  
  <p>it's used in my grid:</p>
  
  <pre><code> var grid = new Ext.grid.GridPanel({
          store: store,
          columns: [
              expander,
          ...
  </code></pre>
  
  <p>Now i want all expander rows to be expanded by deafult.</p>
  
  <p>I'm trying to use <code>expander.expandRow(grid.view.getRow(0));</code> (i think if i make it, i'll be able to use a for loop :) but i get an error</p>
  
  <pre><code>this.mainBody is undefined @ ***/ext/ext-all.js:11
  </code></pre>
  
  <p>Please, help me to expand all rows of my grid! Thanks!</p>