title: pre-selecting value in Combo box in extjs
body: <p>I want to implement the following combobox in ExtJS. The question is, how to make the third option selected by default?</p>
  
  <pre><code>&lt;select name="meter_payment_option" onChange="smart_meter(this.value)"&gt; 
      &lt;option value="1"&gt;All Up-Front&lt;/option&gt; 
      &lt;option value="2"&gt;Reduced Up-Front&lt;/option&gt; 
      &lt;option value="3" selected="selected"&gt;No Up-Front&lt;/option&gt; 
  &lt;/select&gt; 
  </code></pre>
  
  <p>What I currently have is:</p>
  
  <pre><code>var meter_payment_option_values = new Ext.data.SimpleStore({
      fields: ['id', 'value'],
      data: [
          ['1', 'All Up-Front'],
          ['2', 'Reduced Up-Front'],
          ['3', 'No Up-Front']]
  });
  
  var smart_meter_term = new Ext.form.ComboBox({
      name: 'smart_meter_term',
      editable: false,
      typeAhead: false,
      allowblank: false,
      triggerAction: 'all',
      hiddenName: 'my_dropdown',
      fieldLabel: 'SmartM.T',
      store: meter_payment_option_values,
      displayField: 'value',
      valueField: 'id',
      mode: 'local'
  });
  </code></pre>
  
  <p>How do I make the 3rd option (No Up-Front) selected by default?</p>