Index: program/include/main.inc
===================================================================
--- program/include/main.inc	(revision 532844b67740c96396d668745f4c59f7ebec81b2)
+++ program/include/main.inc	(revision 5e804573838afbfea4ccfcb321eca7ddd3be79ce)
@@ -843,4 +843,7 @@
   {
   global $DB, $CONFIG, $sess_user_lang;
+  
+  // merge (partial) prefs array with existing settings
+  $a_user_prefs += (array)$_SESSION['user_prefs'];
   
   $DB->query("UPDATE ".get_table_name('users')."