14
You are looking in wrong file!
File is blocks/multimenu_functions.php
Changed the code a little, try this:
//hack
if ($new_messages > 0) {
$title = preg_replace('/{pm_new}/', '<span style="color:#ff0000; font-weight: bold;">'.$new_messages.'</span>', $title);
} else {
$title = preg_replace('/{pm_new}/', $new_messages, $title);
}
//end of hack