An useful way to test if you have correctly implemented these changes is to activate RTL in your local copy of ImpressCMS by going to "ICMS_ROOT/language/your_language/global.php" and change the value of "_ADM_USE_RTL" to "1" like this:
define("_ADM_USE_RTL","1");
This Post was from: https://www.impresscms.org/iforum/viewtopic.php?topic_id=2599&post_id=24389