Index: trunk/core/units/admin/admin_tag_processor.php
===================================================================
diff -u -N -r5005 -r5177
--- trunk/core/units/admin/admin_tag_processor.php	(.../admin_tag_processor.php)	(revision 5005)
+++ trunk/core/units/admin/admin_tag_processor.php	(.../admin_tag_processor.php)	(revision 5177)
@@ -339,7 +339,7 @@
 		function ListCatalogTabs($params)
 		{
 			$ret = '';
-			$special = $params['special'];
+			$special = isset($params['special']) ? $params['special'] : '';
 			$block_params = Array('name' => $params['render_as']);
 			foreach ($this->Application->ModuleInfo as $module_name => $module_info) {
 				$prefix = $module_info['Var'];