[+validationmessage+] - This should be somewhere in your form template or document. It is used for any validation error messages. From 1.4.2 the way the placehloder is entered has changed. Firstly you no longer need to place it in the form template. You can now place it anywhere in your document (or even in the global page template). Secondly you don't need to place any hml tags around the placeholder (in fact you probably should not). Any html markup is now included in the $_lang['ef_validation_message'] variable in the eform language files (which you can change as required).
When there is an error, eForm generates new content, taken from the lang file. The English version:
$_lang["ef_validation_message"] = "<div class=\"errors\"><strong>Some errors were detected in your form:</strong><br />[+ef_wrapper+]</div>";
You use the [+validationmessage+] placeholder to position this div element on your page. Your javascript could look for this div (or you could modify this to whatever you choose) and open the toggle block if it exists or is not empty.