If, as a teacher, I want to change a student's choice, I either have to ask them to do it, or else modify the Moodle database directly. It would be useful to be able to do this, especially where Choice is being used to allow students to select seminar groups.
This patch will allow a teacher (or anyone who has mod/choice:deleteresponses capability) to select one or more users in the results table, and change their choice. If the users are in the 'unanswered' column, then they get assigned to the new option. The last-modified time is unchanged by this operation.
If the target option is already full, this will be indicated in the drop-down, but if you attempt to move the user anyway, nothing will happen.
If you attempt to delete a user from the "unanswered" column, nothing will happen.