private function init_filter_custom_fields()
 {
     $key = 'filter_custom_fields';
     if (!$this->exec_cf_mgr) {
         $this->exec_cf_mgr = new exec_cfield_mgr($this->db, $this->args->testproject_id);
     }
     $field_names = $this->exec_cf_mgr->field_names();
     $menu = $this->exec_cf_mgr->html_table_of_custom_field_inputs(self::CF_INPUT_SIZE);
     $selection = $this->exec_cf_mgr->get_set_values();
     // BUGID 3566: show/hide CF
     $ses_string = $this->mode . "_cf_filter_collapsed";
     $collapsed = isset($_SESSION[$ses_string]) ? $_SESSION[$ses_string] : 0;
     $collapsed = isset($_REQUEST['btn_toggle_cf']) ? !$collapsed : $collapsed;
     $_SESSION[$ses_string] = $collapsed;
     $btn_label = $collapsed ? lang_get('btn_show_cf') : lang_get('btn_hide_cf');
     // asimon - 20100713
     // Fixed drag&drop error caused by this function. It always set $this->do_filtering
     // to true here because of the missing $selection in the following if condition.
     // This caused lazy loading and DD to be disabled later.
     // see: http://www.teamst.org/forum/viewtopic.php?f=11&t=3354&sid=70498c57842247114cc7233d0f4e5c51
     if (!$selection || $this->args->reset_filters) {
         // handle filter reset button
         $selection = null;
     } else {
         $this->do_filtering = true;
     }
     if (isset($selection) && is_array($selection) && count($selection)) {
         // BUGID 3414:
         // Insert values chosen by user into html select menu by regex.
         // The $menu string contains lines of which each looks like this, e.g.:
         // <tr><td class="labelHolder">cflabel</td><td><input type="text" name="custom_field_0_1"
         // id="custom_field_0_1" size="32"  maxlength="255" value=""></input></td></tr>
         // For each sent value, search the value="" part there and
         // then insert the real value into the empty "". Depending on type, of course.
         // TODO this stuff could maybe fit better into cfield_mgr class?
         // no magic number: 1 because of course only one replacement per value shall be done
         $limit = 1;
         foreach ($selection as $cf_id => $value) {
             $cf_html_name = $field_names[$cf_id]['cf_name'];
             switch ($field_names[$cf_id]['verbose_type']) {
                 case 'list':
                     // for single selection list, only one value has to be marked with "checked"
                     $pattern = '/(.*name="' . $cf_html_name . '".*value="' . $value . '")(.*)/';
                     // the numbers: 1 is the part before value, 2 after
                     $replacement = '${1} selected ${2}';
                     $menu = preg_replace($pattern, $replacement, $menu, $limit);
                     break;
                 case 'checkbox':
                 case 'multiselection list':
                     // this is similar to single selection list, but a bit more complicated
                     // and needs an additional loop because the selection can have multiple values
                     $value_arr = explode('|', $value);
                     foreach ($value_arr as $single_value) {
                         $pattern = '/(.*id="' . $cf_html_name . '".*value="' . $single_value . '")(.*)/';
                         // the numbers: 1 is the part before value, 2 after
                         $replacement = '${1} selected ${2}';
                         $menu = preg_replace($pattern, $replacement, $menu, $limit);
                     }
                     break;
                 case 'numeric':
                 case 'float':
                 case 'email':
                 case 'string':
                     // for these types, replacement is simple, only replace value=""
                     $pattern = '/(.*name="' . $cf_html_name . '".*value=")(".*)/';
                     // 1 and 2 stand for the first and second pair of braces in above line
                     $replacement = '${1}' . $value . '${2}';
                     $menu = preg_replace($pattern, $replacement, $menu, $limit);
                     break;
                 default:
                     break;
             }
             // end of switch
         }
         // end of foreach
     }
     // BUGID 3566: show/hide CF
     $this->filters[$key] = array('items' => $menu, 'btn_label' => $btn_label, 'collapsed' => $collapsed);
     $this->active_filters[$key] = $selection;
 }