Index: includes/bootstrap.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/bootstrap.inc,v
retrieving revision 1.192
diff -u -p -r1.192 bootstrap.inc
--- includes/bootstrap.inc	10 Sep 2007 12:19:11 -0000	1.192
+++ includes/bootstrap.inc	27 Sep 2007 18:31:21 -0000
@@ -996,6 +996,7 @@ function drupal_maintenance_theme() {
   unicode_check();
   drupal_add_css(drupal_get_path('module', 'system') .'/defaults.css', 'module');
   drupal_add_css(drupal_get_path('module', 'system') .'/system.css', 'module');
+  drupal_add_css(drupal_get_path('module', 'system') .'/system-menus.css', 'module');
   $theme = '';
 
   // Special case registry of theme functions used by the installer
Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.689
diff -u -p -r1.689 common.inc
--- includes/common.inc	27 Sep 2007 17:11:07 -0000	1.689
+++ includes/common.inc	28 Sep 2007 15:27:51 -0000
@@ -1541,6 +1541,32 @@ function drupal_add_css($path = NULL, $t
     if (!isset($css[$media])) {
       $css[$media] = array('module' => array(), 'theme' => array());
     }
+
+    // Allow themes to insert overrides of previously added module CSS files when they share the same name.
+    // This would cause themes/garland/system-menus.css to replace modules/system/system-menus.css.
+    // The preprocess flag from the module is maintained and the order of the override depends on the order
+    // it is set inside the theme's .info file and/or the order this function directly called by the theme.
+    if ($type == 'theme') {
+      foreach ($css[$media]['module'] as $old_path => $old_preprocess) {
+        // Match by style sheet name.
+        if (basename($path) == basename($old_path)) {
+          unset($css[$media]['module'][$old_path]);
+
+          // If the current language is RTL, add the CSS file with RTL overrides.
+          if (defined('LANGUAGE_RTL') && $language->direction == LANGUAGE_RTL) {
+            $rtl_path = str_replace('.css', '-rtl.css', $path);
+            if (file_exists($rtl_path)) {
+              $rtl_old_path = str_replace('.css', '-rtl.css', $old_path);
+              unset($css[$media]['module'][$rtl_old_path]);
+            }
+          }
+          // Set the preprocess state of the current module.
+          $preprocess = $old_preprocess;
+          // Match was made and processed for the override style so exit the search loop.
+          continue;
+        }
+      }
+    }
     $css[$media][$type][$path] = $preprocess;

     // If the current language is RTL, add the CSS file with RTL overrides.
Index: modules/system/system-menus-rtl.css
===================================================================
RCS file: modules/system/system-menus-rtl.css
diff -N modules/system/system-menus-rtl.css
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ modules/system/system-menus-rtl.css	27 Sep 2007 18:31:21 -0000
@@ -0,0 +1,18 @@
+/* $Id$ */
+
+ul.menu {
+  text-align:right;
+}
+ul.menu li {
+  margin: 0 0.5em 0 0;
+}
+li.expanded {
+  padding: 0.2em 0 0 0.5em;
+}
+li.collapsed {
+  list-style-image: url(../../misc/menu-collapsed-rtl.png);
+  padding: 0.2em 0 0 0.5em;
+}
+li.leaf {
+  padding: 0.2em 0 0 0.5em;
+}
Index: modules/system/system-menus.css
===================================================================
RCS file: modules/system/system-menus.css
diff -N modules/system/system-menus.css
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ modules/system/system-menus.css	27 Sep 2007 18:31:22 -0000
@@ -0,0 +1,50 @@
+/* $Id$ */
+
+ul.menu {
+  list-style: none;
+  border: none;
+  text-align:left; /* LTR */
+}
+ul.menu li {
+  margin: 0 0 0 0.5em; /* LTR */
+}
+li.expanded {
+  list-style-type: circle;
+  list-style-image: url(../../misc/menu-expanded.png);
+  padding: 0.2em 0.5em 0 0; /* LTR */
+  margin: 0;
+}
+li.collapsed {
+  list-style-type: disc;
+  list-style-image: url(../../misc/menu-collapsed.png); /* LTR */
+  padding: 0.2em 0.5em 0 0; /* LTR */
+  margin: 0;
+}
+li.leaf {
+  list-style-type: square;
+  list-style-image: url(../../misc/menu-leaf.png);
+  padding: 0.2em 0.5em 0 0; /* LTR */
+  margin: 0;
+}
+li a.active {
+  color: #000;
+}
+td.menu-disabled {
+  background: #ccc;
+}
+ul.links {
+  margin: 0;
+  padding: 0;
+}
+ul.links.inline {
+  display: inline;
+}
+ul.links li {
+  display: inline;
+  list-style-type: none;
+  padding: 0 0.5em;
+}
+.block ul {
+  margin: 0;
+  padding: 0 0 0.25em 1em; /* LTR */
+}
Index: modules/system/system-rtl.css
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system-rtl.css,v
retrieving revision 1.3
diff -u -p -r1.3 system-rtl.css
--- modules/system/system-rtl.css	8 Jun 2007 06:04:15 -0000	1.3
+++ modules/system/system-rtl.css	27 Sep 2007 18:31:22 -0000
@@ -21,22 +21,7 @@ dl.multiselect dt, dl.multiselect dd {
   float: right;
   margin: 0 0 0 1em;
 }
-ul.menu {
-  text-align:right;
-}
-ul.menu li {
-  margin: 0 0.5em 0 0;
-}
-li.expanded {
-  padding: 0.2em 0 0 0.5em;
-}
-li.collapsed {
-  list-style-image: url(../../misc/menu-collapsed-rtl.png);
-  padding: 0.2em 0 0 0.5em;
-}
-li.leaf {
-  padding: 0.2em 0 0 0.5em;
-}
+
 .block ul {
   padding: 0 1em 0.25em 0;
 }
Index: modules/system/system.css
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.css,v
retrieving revision 1.34
diff -u -p -r1.34 system.css
--- modules/system/system.css	6 Sep 2007 13:06:13 -0000	1.34
+++ modules/system/system.css	27 Sep 2007 18:31:22 -0000
@@ -182,58 +182,6 @@ dl.multiselect .form-item {
 }
 
 /*
-** Menus
-*/
-ul.menu {
-  list-style: none;
-  border: none;
-  text-align:left; /* LTR */
-}
-ul.menu li {
-  margin: 0 0 0 0.5em; /* LTR */
-}
-li.expanded {
-  list-style-type: circle;
-  list-style-image: url(../../misc/menu-expanded.png);
-  padding: 0.2em 0.5em 0 0; /* LTR */
-  margin: 0;
-}
-li.collapsed {
-  list-style-type: disc;
-  list-style-image: url(../../misc/menu-collapsed.png); /* LTR */
-  padding: 0.2em 0.5em 0 0; /* LTR */
-  margin: 0;
-}
-li.leaf {
-  list-style-type: square;
-  list-style-image: url(../../misc/menu-leaf.png);
-  padding: 0.2em 0.5em 0 0; /* LTR */
-  margin: 0;
-}
-li a.active {
-  color: #000;
-}
-td.menu-disabled {
-  background: #ccc;
-}
-ul.links {
-  margin: 0;
-  padding: 0;
-}
-ul.links.inline {
-  display: inline;
-}
-ul.links li {
-  display: inline;
-  list-style-type: none;
-  padding: 0 0.5em;
-}
-.block ul {
-  margin: 0;
-  padding: 0 0 0.25em 1em; /* LTR */
-}
-
-/*
 ** Tab navigation
 */
 ul.primary {
Index: modules/system/system.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.module,v
retrieving revision 1.534
diff -u -p -r1.534 system.module
--- modules/system/system.module	27 Sep 2007 13:12:26 -0000	1.534
+++ modules/system/system.module	27 Sep 2007 18:31:22 -0000
@@ -451,6 +451,7 @@ function system_init() {
   // Add the CSS for this module.
   drupal_add_css(drupal_get_path('module', 'system') .'/defaults.css', 'module');
   drupal_add_css(drupal_get_path('module', 'system') .'/system.css', 'module');
+  drupal_add_css(drupal_get_path('module', 'system') .'/system-menus.css', 'module');
 }
 
 /**