For example... (taken from the completion report, but I don't think that matters)
$form = new course_completion_form('completion.php?id='.$id, compact('course'));
The class that instantiates doesn't have a constructor so those parameters must be handled by the base forms class. That's new though - and (I fear) not documented. What do they do...
The actual form definition class now has picked up some extra mysteries such as...
$course = $this->_customdata['course'];
What is "_customdata" ??
Did anybody document anything?