title: IsSetData in gridcontrol is never true when clicking on checkEdit item
body: <p>I have this <code>DevExpress GridContro</code>l which I've added with two coloums the one containing a <code>repositoryItemCheckEdit</code> and the other normal <code>string</code> Category description.</p>
  
  <p>Now I've made the <code>repositoryItemCheckEdit</code> a unbound bool in the property section and added the <code>gridView1_CustomUnboundColumnData</code> event which fires with <code>e.IsGetData</code> true but the the <code>e.IsSetData</code> is never true when I click on the check box. Can anyone explain why this is? 
  Thanks</p>
  
  <pre><code>private void gridView1_CustomUnboundColumnData(object sender, CustomColumnDataEventArgs e)
  {
    if (e.IsGetData)
    {
      string itemKey = ((CategoryTable)(gridControl1.ViewCollection[0]).GetRow(e.RowHandle)).Category;
      if (AddressDoc == itemKey) e.Value = true
      else e.Value = false;
    }
  
    if (e.IsSetData)
      AddressDoc = ((CategoryTable)(gridControl1.ViewCollection[0]).GetRow(e.RowHandle)).Category;
  }
  </code></pre>