title: Implement Exclusive Option in Multi-Select: clear other entries on selecting it, clear it on selecting others
body: <p>I have a Multi-Select where one option must be exclusive:</p>
  <ol>
  <li>If it gets selected, any other prior selections in the Multi-Select are deselected</li>
  <li>If another option gets selected while it is selected, this option is deselected</li>
  </ol>
  <p>I was trying to examine the just-selected option, but <code>.val()</code> gives me the overall selection.</p>
  <pre><code>$('#educationLevel').on('change', function(e) {
      var selection = $(e.target).val();
      // This gives overall selection, not the just-selected one for my checks
  }
  </code></pre>
  <p>Any tips?</p>