I've detected various problems trying to save one online submission in the assignment activity. Steps to reproduce them:

1) create one assignment of type "online".
2) connect as student
3) Introduce the submission (in the html editor). PROBLEM1: I'm not able to upload any file there, should I?
4) Click on "save button. "Your changes have been saved", but with PROBLEM2:: Fatal error: Class 'portfolio_add_button' not found in '/moodle_head/mod/assignment/type/online/assignment.class.php on line 111