Index: program/include/rcube_ui.php
===================================================================
--- program/include/rcube_ui.php	(revision 0c259682f65eaaf23ea4ccb56a706d6baf3007e4)
+++ program/include/rcube_ui.php	(revision 651da7934ed4c13e2cbc2e4a82caf2ebaba87373)
@@ -843,5 +843,5 @@
             $title        = null;
             $folder_class = self::folder_classname($folder['id']);
-            $collapsed    = strpos($collapsed, '&'.rawurlencode($folder['id']).'&') !== false;
+            $is_collapsed = strpos($collapsed, '&'.rawurlencode($folder['id']).'&') !== false;
             $unread       = $msgcounts ? intval($msgcounts[$folder['id']]['UNSEEN']) : 0;
 
@@ -897,5 +897,5 @@
                 html::a($link_attrib, $html_name) .
                 (!empty($folder['folders']) ? html::div(array(
-                    'class' => ($collapsed ? 'collapsed' : 'expanded'),
+                    'class' => ($is_collapsed ? 'collapsed' : 'expanded'),
                     'style' => "position:absolute",
                     'onclick' => sprintf("%s.command('collapse-folder', '%s')", JS_OBJECT_NAME, $js_name)
@@ -909,5 +909,5 @@
 
             if (!empty($folder['folders'])) {
-                $out .= html::tag('ul', array('style' => ($collapsed ? "display:none;" : null)),
+                $out .= html::tag('ul', array('style' => ($is_collapsed ? "display:none;" : null)),
                     self::render_folder_tree_html($folder['folders'], $mbox_name, $jslist, $attrib, $nestLevel+1));
             }