Index: includes/form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.367
diff -u -p -r1.367 form.inc
--- includes/form.inc	27 Aug 2009 04:40:12 -0000	1.367
+++ includes/form.inc	27 Aug 2009 15:35:05 -0000
@@ -992,6 +992,15 @@ function form_builder($form_id, $element
     }
   }
 
+  // Load additional files needed by the element.
+  if (!empty($element['#include_files'])) {
+    foreach ($element['#include_files'] as $file) {
+      if (!empty($file) && file_exists($file)) {
+        require_once DRUPAL_ROOT . '/' . $file;
+      }
+    }
+  }
+
   if (!isset($element['#id'])) {
     $element['#id'] = form_clean_id('edit-' . implode('-', $element['#parents']));
   }