anchor.diff:                  var input = cell.getElementsByTagName("INPUT")[0]
                   registerCellInputHandlers(input)
               });
  -            Event.observe('add-activity-button', "click", addActivityRow)
  +            Event.observe('add-activity-button', 'click', addActivityRow)
  +            Event.observe('select-activity-type', 'change', updateActivitySelector)
           }
   
           Event.observe(window, "load", registerHandlers)
           Event.observe(window, "load", showEmptyMessage)
  +        Event.observe(window, "load", updateActivitySelector)
       </script>
       <style type="text/css">
           #no-activities-message td {
  
positive.code:     <title>Set up Period ${period.name} of ${study.name}</title>
      <tags:includeScriptaculous/>
      <script type="text/javascript">
          function currentActivityCount() {
              return $$('.input-row').length;
          }
  
negative.code:         }
  
          function selectedActivity() {
              return selectedValue('add-activity')
          }
  
          function selectedValue(selectorName) {
              var selector = $(selectorName)
              var selected = selector.options[selector.selectedIndex]
              return {
                  name: selected.text,
  