title: Devexpress SearchLookUpEdit get column value
body: <p>I can't get column value from <code>SearchLookUpEdit</code>. 
  With <code>LookUpEdit</code> i can get it </p>
  
  <pre><code>cbMarket.GetColumnValue("MarketId")
  </code></pre>
  
  <p>in my <code>SearchLookUpEdit</code> there are two table fields. i can get <code>displaytext</code> or <code>valuemember</code>. but specified field i cant.
  thanks for help</p>