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