title: Ext Js combobox value after onchange is value instead of label
body: <p>Just getting frustrated by something that should be an easy fix, but I'm too simple minded to see it :)</p>
  
  <p>I'm having a grid where 1 column is a combobox. The thing works just fine and the correct value is beeing sent through my ajax request, but after I edited the grid row, the combobox disappread and the value that comes into place is not the label, but the value.</p>
  
  <pre><code>editor: new Ext.form.field.ComboBox({
              typeAhead: true,
              lazyRender: true,
              store: new Ext.data.ArrayStore({
                  fields: ['contact', 'contactLabel'],
                  data: [
                      [1,'Jan'],
                      [2,'Jeroen'],
                      [3,'Mattijs'],
                      [4,'Sven'],
                      [5,'Thomas'],
                      [6,'Yoran']
                  ]
              }),
              valueField: 'contact',
              displayField: 'contactLabel',
              hiddenName: 'contact'
          })
  </code></pre>
  
  <p>So what happens is that when I change the combobox to i.e.. "Thomas", the value of the cell becomes "5", instead of "Thomas". I thought that defining value/display fields would make a difference, but it does not.</p>
  
  <p>Anyone that knows the answer?</p>