Index: user.php
===================================================================
--- user.php	(revision 31096)
+++ user.php	(working copy)
@@ -1387,7 +1387,7 @@
 		'show_option_all' => '', 'show_option_none' => '', 'hide_if_only_one_author' => '',
 		'orderby' => 'display_name', 'order' => 'ASC',
 		'include' => '', 'exclude' => '', 'multi' => 0,
-		'show' => 'display_name', 'echo' => 1,
+		'show' => '', 'echo' => 1,
 		'selected' => 0, 'name' => 'user', 'class' => '', 'id' => '',
 		'blog_id' => $GLOBALS['blog_id'], 'who' => '', 'include_selected' => false,
 		'option_none_value' => -1
@@ -1402,7 +1402,7 @@
 	$option_none_value = $r['option_none_value'];
 
 	$query_args = wp_array_slice_assoc( $r, array( 'blog_id', 'include', 'exclude', 'orderby', 'order', 'who' ) );
-	$query_args['fields'] = array( 'ID', 'user_login', $show );
+	$query_args['fields'] = array( 'ID', 'user_login', 'display_name' );
 	$users = get_users( $query_args );
 
 	$output = '';
@@ -1431,14 +1431,14 @@
 			if ( $_selected ) {
 				$found_selected = true;
 			}
-			$display = ! empty( $user->$show ) ? $user->$show : '('. $user->user_login . ')';
+			$display = ! empty( $user->$show ) ? $user->$show : $user->display_name . ' ('. $user->user_login . ')';
 			$output .= "\t<option value='$user->ID'$_selected>" . esc_html( $display ) . "</option>\n";
 		}
 
 		if ( $r['include_selected'] && ! $found_selected && ( $r['selected'] > 0 ) ) {
 			$user = get_userdata( $r['selected'] );
 			$_selected = selected( $user->ID, $r['selected'], false );
-			$display = ! empty( $user->$show ) ? $user->$show : '('. $user->user_login . ')';
+			$display = ! empty( $user->$show ) ? $user->$show : $user->display_name . ' ('. $user->user_login . ')';
 			$output .= "\t<option value='$user->ID'$_selected>" . esc_html( $display ) . "</option>\n";
 		}