Index: modules/system/system.admin.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/system/system.admin.inc,v
retrieving revision 1.309
diff -u -p -r1.309 system.admin.inc
--- modules/system/system.admin.inc	24 Sep 2010 21:36:22 -0000	1.309
+++ modules/system/system.admin.inc	28 Sep 2010 07:12:28 -0000
@@ -210,7 +210,9 @@ function system_themes_page() {
     if (!empty($theme->info['hidden'])) {
       continue;
     }
-    $admin_theme_options[$theme->name] = $theme->info['name'];
+    if (empty($theme->info['type']) || !($theme->info['type'] === 'frontend-theme')) {
+      $admin_theme_options[$theme->name] = $theme->info['name'];
+    }
     $theme->is_default = ($theme->name == $theme_default);
 
     // Identify theme screenshot.
@@ -264,12 +266,14 @@ function system_themes_page() {
             'query' => $query,
             'attributes' => array('title' => t('Disable !theme theme', array('!theme' => $theme->info['name']))),
           );
-          $theme->operations[] = array(
-            'title' => t('Set default'),
-            'href' => 'admin/appearance/default',
-            'query' => $query,
-            'attributes' => array('title' => t('Set !theme as default theme', array('!theme' => $theme->info['name']))),
-          );
+          if(empty($theme->info['type']) || ($theme->info['type'] !== 'admin-theme')) {
+            $theme->operations[] = array(
+              'title' => t('Set default'),
+              'href' => 'admin/appearance/default',
+              'query' => $query,
+              'attributes' => array('title' => t('Set !theme as default theme', array('!theme' => $theme->info['name']))),
+            );
+          }
         }
       }
       else {
@@ -279,12 +283,14 @@ function system_themes_page() {
           'query' => $query,
           'attributes' => array('title' => t('Enable !theme theme', array('!theme' => $theme->info['name']))),
         );
-        $theme->operations[] = array(
-          'title' => t('Enable and set default'),
-          'href' => 'admin/appearance/default',
-          'query' => $query,
-          'attributes' => array('title' => t('Enable !theme as default theme', array('!theme' => $theme->info['name']))),
-        );
+        if (empty($theme->info['type']) || ($theme->info['type'] !== 'admin-theme')) {
+          $theme->operations[] = array(
+            'title' => t('Enable and set default'),
+            'href' => 'admin/appearance/default',
+            'query' => $query,
+            'attributes' => array('title' => t('Enable !theme as default theme', array('!theme' => $theme->info['name']))),
+          );
+        }
       }
     }