title: how can dojo.FilteringSelect be configured to match wildcard values?
body: <p>Below is a sample of a filteringSelect populated with user data. My goal is to have perform wilcard match on the displayed values. for example, if the user types 'son', the dropdown matches will be "homer simpSON' and 'carl calSON'. 
  By default, the match will only be on the beginning of the label.</p>
  
  <p>I tried changing dijit.byId('userselect').searchAttr, but setting it to anything but a string causes erronious behaviour.</p>
  
  <pre><code>&lt;input id="userselect"&gt;
  
  &lt;script type="text/javascript"&gt;
      dojo.require("dijit.form.FilteringSelect");
      dojo.require("dojo.data.ItemFileReadStore");
  
      var user_data = {
          "itentifier":"user_id",
          "label":"label",
          "items":[
              {"first_name":"Waylon","last_name":"Smithers","label":"Waylon Smithers","user_id":7}
              ,{"first_name":"Carl","last_name":"Carlson","label":"Carl Carlson","user_id":6}
              ,{"first_name":"Homer","last_name":"Simpson","label":"Homer Simpson","user_id":4}
              ,{"first_name":"Lenny","last_name":"Leonard","label":"Lenny Leonard","user_id":5}
              ,{"first_name":"Montgomery","last_name":"Burns","label":"Montgomery Burns","user_id":8}
              ]
          };
  
      dojo.addOnLoad(function() {
          var userStore = new dojo.data.ItemFileReadStore({
              //url: "/user/lookup",
              data: user_data
          });
          var filteringSelect = new dijit.form.FilteringSelect({
              id: "userselect",
              name: "userselect",
              store: userStore,
              searchAttr: 'label' //["first_name", "last_name", "oasis"]
          },
          "userselect");
      });
  &lt;/script&gt;
  </code></pre>