--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/program/steps/mail/pagenav.inc	Thu Jan 04 15:52:31 2018 -0500
@@ -0,0 +1,66 @@
+<?php
+
+/**
+ +-----------------------------------------------------------------------+
+ | program/steps/mail/pagenav.inc                                        |
+ |                                                                       |
+ | This file is part of the Roundcube Webmail client                     |
+ | Copyright (C) 2005-2016, The Roundcube Dev Team                       |
+ |                                                                       |
+ | Licensed under the GNU General Public License version 3 or            |
+ | any later version with exceptions for skins & plugins.                |
+ | See the README file for a full license statement.                     |
+ |                                                                       |
+ | PURPOSE:                                                              |
+ |   Updates message page navigation controls                            |
+ |                                                                       |
+ +-----------------------------------------------------------------------+
+ | Author: Aleksander Machniak <alec@alec.pl>                            |
+ +-----------------------------------------------------------------------+
+*/
+
+$uid   = rcube_utils::get_input_value('_uid', rcube_utils::INPUT_GET);
+$index = $RCMAIL->storage->index(null, rcmail_sort_column(), rcmail_sort_order());
+$cnt   = $index->count_messages();
+
+if ($cnt && ($pos = $index->exists($uid, true)) !== false) {
+    $prev  = $pos ? $index->get_element($pos-1) : 0;
+    $first = $pos ? $index->get_element('FIRST') : 0;
+    $next  = $pos < $cnt-1 ? $index->get_element($pos+1) : 0;
+    $last  = $pos < $cnt-1 ? $index->get_element('LAST') : 0;
+}
+else {
+    // error, this will at least disable page navigation
+    $OUTPUT->command('set_rowcount', '');
+    $OUTPUT->send();
+}
+
+// Set UIDs and activate navigation buttons
+if ($prev) {
+    $OUTPUT->set_env('prev_uid', $prev);
+    $OUTPUT->command('enable_command', 'previousmessage', 'firstmessage', true);
+}
+
+if ($next) {
+    $OUTPUT->set_env('next_uid', $next);
+    $OUTPUT->command('enable_command', 'nextmessage', 'lastmessage', true);
+}
+
+if ($first) {
+    $OUTPUT->set_env('first_uid', $first);
+}
+
+if ($last) {
+    $OUTPUT->set_env('last_uid', $last);
+}
+
+// Don't need a real messages count value
+$OUTPUT->set_env('messagecount', 1);
+
+// Set rowcount text
+$OUTPUT->command('set_rowcount', $RCMAIL->gettext(array(
+    'name' => 'messagenrof',
+    'vars' => array('nr'  => $pos+1, 'count' => $cnt)
+)));
+
+$OUTPUT->send();