Index: modules/system/system.api.php
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.api.php,v
retrieving revision 1.49
diff -u -r1.49 system.api.php
--- modules/system/system.api.php	15 Jul 2009 02:08:41 -0000	1.49
+++ modules/system/system.api.php	15 Jul 2009 09:40:31 -0000
@@ -151,18 +151,36 @@
  * to the header at this point, and developers wishing to do so should use
  * hook_init() instead.
  *
- * @param $main
- *   Whether the current page is the front page of the site.
  * @return
  *   The HTML to be inserted.
  */
-function hook_footer($main = 0) {
+function hook_footer() {
   if (variable_get('dev_query', 0)) {
-    return '<div style="clear:both;">' . devel_query_table() . '</div>';
+    return array('devel' => array(
+        '#markup' => '<div style="clear:both;">' . devel_query_table() . '</div>',
+      ),
+    );
   }
 }
 
 /**
+ * Alter closing HTML.
+ *
+ * This hook enables modules to alter HTML just before the \</body\> closing
+ * tag of web pages. This is useful for changing HTML added by other modules
+ * using hook_footer.
+ *
+ * @param $closure
+ *   A renderable array as returned by hook_footer
+ * @return
+ *   Altered HTML to be inserted.
+ */
+function hook_footer_alter($closure) {
+  // Change the css file used to style the toolbar.
+  $closure['toolbar']['#attached_css'][0] = drupal_get_path('mymodule', '/toolbar.css');
+}
+
+/**
  * Perform necessary alterations to the JavaScript before it is presented on
  * the page.
  *
Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.934
diff -u -r1.934 common.inc
--- includes/common.inc	14 Jul 2009 10:22:15 -0000	1.934
+++ includes/common.inc	15 Jul 2009 09:40:28 -0000
@@ -3731,6 +3731,21 @@
 }
 
 /**
+ * Execute hook_footer() which is run at the end of the page right before the
+ * close of the body tag.
+ *
+ * @return
+ *   A string containing the results of the hook_footer() calls.
+ *
+ * @see hook_footer_alter()
+ */
+function drupal_render_footer() {
+  $closure = module_invoke_all('footer');
+  drupal_alter('footer', $closure);
+  return drupal_render($closure);
+}
+
+/**
  * Renders HTML given a structured array tree.
  *
  * Recursively iterates over each of the array elements, generating HTML code.
Index: includes/theme.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/theme.inc,v
retrieving revision 1.498
diff -u -r1.498 theme.inc
--- includes/theme.inc	14 Jul 2009 10:22:17 -0000	1.498
+++ includes/theme.inc	15 Jul 2009 09:40:29 -0000
@@ -1703,20 +1703,6 @@
 }
 
 /**
- * Execute hook_footer() which is run at the end of the page right before the
- * close of the body tag.
- *
- * @param $main (optional)
- *   Whether the current page is the front page of the site.
- * @return
- *   A string containing the results of the hook_footer() calls.
- */
-function theme_closure($main = 0) {
-  $footer = module_invoke_all('footer', $main);
-  return implode("\n", $footer) . drupal_get_js('footer');
-}
-
-/**
  * Format a username.
  *
  * @param $object
@@ -1951,7 +1937,7 @@
   $variables['rdf_namespaces']    = drupal_get_rdf_namespaces();
   $variables['grddl_profile']     = 'http://ns.inria.fr/grddl/rdfa/';
   // Closure should be filled last.
-  $variables['closure']           = theme('closure');
+  $variables['closure'] = drupal_render_footer();
 
   if ($node = menu_get_object()) {
     $variables['node'] = $node;