title: jQuery - prevent option deselect in select multiple
body: <p>Is it possible to prevent an option from being deselected in a select multiple control? Also it must not deselect any other selected options. I have tried:</p>
  
  <pre><code>$('#selections option').click(function(){
      $(this).prop('selected', true);
  });
  </code></pre>
  
  <p>Doesn't seem to work. Anyone know how I can achieve this?</p>