Index: wp-admin/includes/template.php
===================================================================
--- wp-admin/includes/template.php	(revision 15173)
+++ wp-admin/includes/template.php	(working copy)
@@ -3900,7 +3900,7 @@
  * @param string $id Screen id, optional.
  */
 function set_current_screen( $id =  '' ) {
-	global $current_screen, $hook_suffix, $typenow;
+	global $current_screen, $hook_suffix, $typenow, $taxnow;
 
 	if ( empty($id) ) {
 		$current_screen = $hook_suffix;
@@ -3932,6 +3932,11 @@
 			$typenow = 'post';
 		$current_screen->id = $typenow;
 		$current_screen->post_type = $typenow;
+	} elseif ( 'edit-tags' == $current_screen->id ) {
+		if ( empty($taxnow) )
+			$taxnow = 'post_tag';
+		$current_screen->id = 'edit-' . $taxnow;
+		$current_screen->taxonomy = $taxnow;
 	}
 
 	$current_screen = apply_filters('current_screen', $current_screen);
Index: wp-admin/edit-tags.php
===================================================================
--- wp-admin/edit-tags.php	(revision 15173)
+++ wp-admin/edit-tags.php	(working copy)
@@ -296,17 +296,16 @@
 </div>
 
 <div class="clear"></div>
-<?php $table_type = ('category' == $taxonomy ? 'categories' : 'edit-tags'); ?>
 <table class="widefat tag fixed" cellspacing="0">
 	<thead>
 	<tr>
-<?php print_column_headers($table_type); ?>
+<?php print_column_headers($current_screen); ?>
 	</tr>
 	</thead>
 
 	<tfoot>
 	<tr>
-<?php print_column_headers($table_type, false); ?>
+<?php print_column_headers($current_screen, false); ?>
 	</tr>
 	</tfoot>
 
Index: wp-admin/admin.php
===================================================================
--- wp-admin/admin.php	(revision 15173)
+++ wp-admin/admin.php	(working copy)
@@ -81,10 +81,15 @@
 }
 
 if ( isset($_GET['post_type']) )
-	$typenow = sanitize_user($_GET['post_type'], true);
+	$typenow = sanitize_key($_GET['post_type']);
 else
 	$typenow = '';
 
+if ( isset($_GET['taxonomy']) )
+	$taxnow = sanitize_key($_GET['taxonomy']);
+else
+	$taxnow = '';
+
 require(ABSPATH . 'wp-admin/menu.php');
 
 if ( current_user_can( 'manage_options' ) )