title: GXT (Ext GWT) problem with SimpleComboBox
body: <p>When creating a GXT SimpleComboBox (as in the accepted answer <a href="https://stackoverflow.com/questions/1161796/how-to-use-ext-gwt-combobox/1167547#1167547">here</a>),</p>
  
  <pre><code>    final FormPanel fp = new FormPanel();
  
      SimpleComboBox&lt;String&gt; combo = new SimpleComboBox&lt;String&gt;();
      combo.add("One");
      combo.add("Two");
      combo.add("Three");
      combo.setSimpleValue("Two"); // I'd like to preselect that value
  
      fp.add(combo);
      RootPanel.get().add(fp);
  </code></pre>
  
  <p>my combo box only contains the value "Two". The values "One" and "Three" are completely removed from the combo box. This doesn't happen, when I delete the line <code>combo.setSimpleValue("Two");</code></p>
  
  <p>I'm using GXT 2.2.3 and GWT 2.2.0 (tested on Linux/Firefox and Linux/Chrome). Is this a bug / did it work in older versions of GXT/GWT, or am I doing something wrong?</p>
  
  <h1>Update</h1>
  
  <p>I accepted an answer, and it solves the problem: Add the line</p>
  
  <pre><code>combo.setTriggerAction(TriggerAction.ALL);
  </code></pre>
  
  <p>But I'm still looking for an explanation!</p>