anchor.diff:  
     <div class="row-fluid">
       <div class="span4">
  -      <%= select_tag(:event_type, options_for_select([
  -        ['Please select an event type', ''],
  +      Event type<br>
  +      <select id="event_type" name="event_type">
  +      <%= options_for_select([
  +        ['', ''],
           ['Cites Animal Committee', 'cites_acs'],
  -        ['Cites Plant Committee', 'cites_pcs']
  -      ])) %>
  +        ['Cites Plant Committee', 'cites_pcs'],
  +        ['Cites Technical Committee', 'cites_tcs'],
  +        ['Cites Extraordinary Meetings', 'cites_extraordinary_meetings'],
  +        ['European Commission SRG', 'ec_srgs']
  +      ]) %>
  +      </select>
       </div>
       <div class="span4" >
  -      <select id="event" name="events" style="visibility: hidden"></select>
  +      Event<br>
  +      <select id="event" name="event" disabled>
  +        <option value=""></option>
  +      </select>
       </div>
  -    <div class="span4">...</div>
  +    <div class="span4">
  +      Document type<br>
  +      <select id="document_type" name="document_type" disabled>
  +        <option value=""></option>
  +      </select>
  +    </div>
     </div>
   
     <div class="row-fluid">
  -    <a href="" id="event_link" style="visibility: hidden">
  +    <a href="" id="event_link" style="visibility: hidden" disabled>
         Go to event upload document page
       </a>
     </div>
  
positive.code:     $event = $('#event'),
      $event_link = $('#event_link');
  
    function disableElements(selectors) {
      $.each(selectors, function() {
        this.css('visibility', 'hidden');
      });
    }
  
    function enableElements(selectors) {
      $.each(selectors, function() {
        this.css('visibility', 'visible');
      });
    }
  
    $event_type.change( function() {
      var event_type = $(this).val();
      if (event_type) {
        enableElements([$event]);
        $.getJSON(event_type+'.json', function( data ) {
          var items = ['<option value="">Please select an event</option>'];
          $.each(data, function( idx, obj ) {
            items.push(
              "<option value='" + obj.value + "'>" + obj.text + "</option>");
  
negative.code:         $('#event').html(items.join( "" ));
        });
      } else {
        $event.attr('disabled', true);
        $event_link.css('visibility', 'hidden');
      }
    });
  
    $event.change( function() {
      var event = $(this).val();
      if (event) {
        $event_link.attr('disabled', false);
        $event_link.css('visibility', 'visible');
        $event_link.attr('href', 'events/'+event+'/documents');
      } else {
        $event_link.css('visibility', 'hidden');
      }
    });
  
  