Allow to manually reorder "normal" folders

program/actions/settings/folder_edit.php

@@ -156,6 +156,16 @@ public static function folder_form($attrib)
                 'label' => $rcmail->gettext('parentfolder'),
                 'value' => $select->show($selected),
             ];
+
+            $upBtn = new html_button(['id' => 'move-folder-up', 'class' => 'move-folder-up']);
+            $downBtn = new html_button(['id' => 'move-folder-down', 'class' => 'move-folder-down']);
+            $form['props']['fieldsets']['location']['content']['order'] = [
+                'label' => $rcmail->gettext('reorder_folder'),
+                'value' => html::div([], [
+                    $upBtn->show($rcmail->gettext('reorder_folder_up')),
+                    $downBtn->show($rcmail->gettext('reorder_folder_down')),
+                ]),
+            ];
         }
 
         // Settings

program/actions/settings/folder_reorder.php

@@ -0,0 +1,22 @@
+<?php
+
+class rcmail_action_settings_folder_reorder extends rcmail_action_settings_folders
+{
+    protected static $mode = self::MODE_AJAX;
+
+    /**
+     * Request handler.
+     *
+     * @param array $args Arguments from the previous step(s)
+     */
+    #[\Override]
+    public function run($args = [])
+    {
+        $rcmail = rcmail::get_instance();
+        $list = array_flip(rcube_utils::get_input_value('folderorder', rcube_utils::INPUT_POST, true));
+        $rcmail->user->save_prefs(['folder_order' => $list]);
+
+        $rcmail->output->show_message('successfullysaved', 'confirmation');
+        $rcmail->output->send();
+    }
+}

program/actions/settings/folders.php

@@ -34,6 +34,7 @@ public function run($args = [])
         $storage = $rcmail->get_storage();
 
         $rcmail->output->set_pagetitle($rcmail->gettext('folders'));
+        $rcmail->output->set_env('folder_ordered_manually', !empty($rcmail->user->get_prefs()['folder_order']));
         $rcmail->output->set_env('prefix_ns', $storage->get_namespace('prefix'));
         $rcmail->output->set_env('quota', (bool) $storage->get_capability('QUOTA'));
         $rcmail->output->include_script('treelist.js');
@@ -262,6 +263,10 @@ public static function folder_tree_element($folders, &$key, &$js_folders)
             'id' => $idx,
             'class' => trim($data['class'] . ' mailbox'),
         ];
+        // Only allow reordering of non-protected folders.
+        if ($data['protected']) {
+            $attribs['class'] .= ' protected';
+        }
 
         if (!isset($data['level'])) {
             $data['level'] = 0;