#2039 by Boris Mann ("My first diff to the list"), moshe weitzman, and David Lesieur, nested lists.

CHANGELOG.txt

@@ -45,6 +45,7 @@ Drupal x.x.x, xxxx-xx-xx (development version)
 - upgrade system:
     * created space for update branches.
 - split up and removed drupal.css.
+- added nested lists generation.
 
 Drupal 4.7.0, 2006-05-01
 ------------------------

includes/theme.inc

@@ -835,8 +835,9 @@ function theme_mark($type = MARK_NEW) {
  * @param $items
  *   An array of items to be displayed in the list. If an item is a string,
  *   then it is used as is. If an item is an array, then the "data" element of
- *   the array is used as the contents of the list item and all other elements
- *   are treated as attributes of the list item element.
+ *   the array is used as the contents of the list item. If an item is an array
+ *   with a "children" element, those children are displayed in a nested list.
+ *   All other elements are treated as attributes of the list item element.
  * @param $title
  *   The title of the list.
  * @param $attributes
@@ -856,11 +857,15 @@ function theme_item_list($items = array(), $title = NULL, $type = 'ul', $attribu
     $output .= "<$type" . drupal_attributes($attributes) . '>';
     foreach ($items as $item) {
       $attributes = array();
+      $children = array();
       if (is_array($item)) {
         foreach ($item as $key => $value) {
           if ($key == 'data') {
             $data = $value;
           }
+          elseif ($key == 'children') {
+            $children = $value;
+          }
           else {
             $attributes[$key] = $value;
           }
@@ -869,6 +874,9 @@ function theme_item_list($items = array(), $title = NULL, $type = 'ul', $attribu
       else {
         $data = $item;
       }
+      if (count($children) > 0) {
+        $data .= theme_item_list($children, NULL, $type, $attributes); // Render nested list
+      }
       $output .= '<li' . drupal_attributes($attributes) . '>'. $data .'</li>';
     }
     $output .= "</$type>";