title: Enable one option group at a time
body: <pre><code>&lt;select name="campus"&gt;    
      &lt;optgroup label="Northwest"&gt;
          &lt;option value="1"&gt;Gary&lt;/option&gt;
          &lt;option value="2"&gt;Valparaiso&lt;/option&gt;
          &lt;option value="3"&gt;East Chicago&lt;/option&gt;
      &lt;/optgroup&gt;
      &lt;optgroup label="North Central"&gt;
          &lt;option value="4"&gt;South Bend&lt;/option&gt;
          &lt;option value="5"&gt;Elkhart&lt;/option&gt;
          &lt;option value="6"&gt;Warsaw&lt;/option&gt;
      &lt;/optgroup&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>I have multiple <code>&lt;optgroup&gt;</code>s in my dropdown. I am using the multiselect plugin. How can I restrict to select only one optgroup selection? That is, when one option in a group is selected, options in other groups should be disabled.</p>