function displayTree(Collections $elem, $html, $value, $name, $user = null)
 {
     $img_expand = 'blue_expand.png';
     $img_expand_up = 'blue_expand_up.png';
     if ($elem->hasChild()) {
         $html .= '<ul>';
         foreach ($elem->getChilds() as $child) {
             $html .= "<li class=\"rid_" . $child->getId() . "\"";
             if ($child->isEncodable()) {
                 $html .= ' data-enc="true" ';
             }
             $html .= "><div class=\"col_name\">";
             $html .= image_tag($img_expand, array('alt' => '+', 'class' => 'tree_cmd collapsed'));
             $html .= image_tag($img_expand_up, array('alt' => '-', 'class' => 'tree_cmd expanded hidden'));
             $html .= "<span>" . $child->getName() . "</span>";
             $options = array('type' => 'checkbox', 'class' => 'col_check', 'value' => $child->getId(), 'name' => $name);
             if (is_array($value) && in_array($child->getId(), $value)) {
                 $options['checked'] = "checked";
             }
             if ($name != '') {
                 $html .= '<label class="chk">' . $this->renderTag('input', $options) . '</label>';
             } else {
                 if (!$this->getOption('is_choose')) {
                     $html .= ' ' . image_tag('info.png', array('title' => 'info', 'class' => 'extd_info', 'data-manid' => $child->getMainManagerRef(), 'data-staffid' => $child->getStaffRef()));
                     if ($user->isA(Users::ADMIN) || $user->isAtLeast(Users::MANAGER) && $child->getTypeInCol() >= Users::MANAGER) {
                         $html .= link_to(image_tag('edit.png', array('title' => 'Edit Collection', 'class' => 'collection_edit')), 'collection/edit?id=' . $child->getId());
                         $html .= link_to(image_tag('duplicate.png', array('title' => 'Duplicate Collection')), 'collection/new?duplicate_id=' . $child->getId());
                     }
                 }
             }
             $html .= "</div>";
             $html .= $this->displayTree($child, '', $value, $name, $user) . '</li>';
         }
         $html .= '</ul>';
     }
     return $html;
 }