NDOJ/templates/widgets/select_all.html

<div style="border:none" id="{{ select_all_name }}">
  <div class="original-checkboxes">{{ original_widget }}</div>
  {% if empty %}
    {{ _('Nothing here.') }}
  {% else %}
    <label>
      <input id="{{ select_all_id }}" name="{{ select_all_name }}"{% if all_selected %} checked{% endif %}
        type="checkbox" class="checkall"> {{ _('Check all') }}
    </label>
  {% endif %}
</div>
<style>
  div.original-checkboxes ul {
    margin: 0 0 0 2em;
    padding: 0;
    list-style-type: none;
    -moz-columns: 15em 5;
    -webkit-columns: 15em 5;
    columns: 15em 5
  }

  div.original-checkboxes ul li {
    list-style-type: none;
  }
</style>
<script type="text/javascript">
  django.jQuery(function ($) {
    var box = $('div#' + '{{ select_all_name }}');
    var original = box.find('.original-checkboxes');
    $('.checkall').click(function () {
      original.find(':checkbox').prop('checked', this.checked);
    });
  });
</script>