title: Add an item ("---Please select---") to a combo box with a data source
body: <p>I have a combo box with data source but I want to add an item.</p>
  
  <p>I want it to look like this.</p>
  
  <pre><code>----Please select one---     //the item I want to add 
  Tokyo                        //the items that came from the database
  Osaka                        //the items that came from the database
  Boston                       //the items that came from the database
  Manila                       //the items that came from the database
  </code></pre>
  
  <p>How do I remedy this?</p>
  
  <p>Thanks </p>