Index: wp-admin/edit-comments.php
===================================================================
--- wp-admin/edit-comments.php	(revision 16587)
+++ wp-admin/edit-comments.php	(working copy)
@@ -206,7 +206,6 @@
 	<input type="text" id="comment-search-input" name="s" value="<?php _admin_search_query(); ?>" />
 	<?php submit_button( __( 'Search Comments' ), 'button', 'submit', false ); ?>
 </p>
-<input type="hidden" name="mode" value="<?php echo esc_attr($mode); ?>" />
 <?php if ( $post_id ) : ?>
 <input type="hidden" name="p" value="<?php echo esc_attr( intval( $post_id ) ); ?>" />
 <?php endif; ?>
Index: wp-admin/includes/class-wp-comments-list-table.php
===================================================================
--- wp-admin/includes/class-wp-comments-list-table.php	(revision 16588)
+++ wp-admin/includes/class-wp-comments-list-table.php	(working copy)
@@ -21,11 +21,7 @@
 	var $pending_count = array();
 
 	function WP_Comments_List_Table() {
-		global $mode;
-
-		$mode = ( empty( $_REQUEST['mode'] ) ) ? 'detail' : $_REQUEST['mode'];
-
-		if ( get_option('show_avatars') && 'single' != $mode )
+		if ( get_option('show_avatars') )
 			add_filter( 'comment_author', 'floated_admin_avatar' );
 
 		parent::WP_List_Table( array(
@@ -232,7 +228,7 @@
 	}
 
 	function get_columns() {
-		global $mode;
+		global $post_id;
 
 		$columns = array();
 
@@ -242,7 +238,7 @@
 		$columns['author'] = __( 'Author' );
 		$columns['comment'] = _x( 'Comment', 'column name' );
 
-		if ( 'single' !== $mode )
+		if ( !$post_id )
 			$columns['response'] = _x( 'In Response To', 'column name' );
 
 		return $columns;