Ticket #28350: 28350-3.patch

wp-includes/admin-bar.php

@@ -493 +493 @@
                         && ( $post_type_object->public )
                         && ( $post_type_object->show_in_admin_bar ) )
                 {
-                        $wp_admin_bar->add_menu( array(
-                                'id' => 'view',
-                                'title' => $post_type_object->labels->view_item,
-                                'href' => get_permalink( $post->ID )
-                        ) );
+                        if( 'draft' == $post->post_status ) {
+                                $preview_link = set_url_scheme( get_permalink( $post->ID ) );
+                                /** This filter is documented in wp-admin/includes/meta-boxes.php */
+                                $preview_link = esc_url( apply_filters( 'preview_post_link', add_query_arg( 'preview', 'true', $preview_link ) ) );
+                                $wp_admin_bar->add_menu( array(
+                                        'id' => 'preview',
+                                        'title' => __( 'Preview' ),
+                                        'href' => $preview_link
+                                ) );
+                        } else {
+                                $wp_admin_bar->add_menu( array(
+                                        'id' => 'view',
+                                        'title' => $post_type_object->labels->view_item,
+                                        'href' => get_permalink( $post->ID )
+                                ) );
+                        }
                 } elseif ( 'edit-tags' == $current_screen->base
                         && isset( $tag ) && is_object( $tag )
                         && ( $tax = get_taxonomy( $tag->taxonomy ) )