The visibility of coursemodules is now always set through the function set_coursemodule_visible() in order to make sure that the associated events get updated in the calendar appropriately.
If moving a coursemodule to a hidden section then the module is set to hidden as well and its events are hidden in the calendar.
If deleting a coursemodule its events are deleted from the calendar.
The function choose_from_menu() has an extra optional argument $disabled which, when set to true, will disable the menu.
For the sake of consistency the function set_groupmode_for_module has been renamed to set_coursemodule_groupmode and the functions show_course_module() and hide_course_module() have been combined to set_coursemodule_visible().
These are the changes from MOODLE_13_STABLE, merged into trunk
The tag MOODLE_13_MERGED on the MOODLE_13_STABLE branch now refers to this point
The biggest changes here are the fixes for HTML editor in all standard modules
Sections covers "weeks", "topics" and anything else that may come along.
Note, again, some databases have changed esp course_weeks -> course_sections
and several fields called "week" are now "section. Also course no longer
has an enddate, but instead has a numsections field.