Note This only affects the "Add a gradebook item" helper. At this time, I believe only the assignment2 contrib tool is using this helper.
Currently, you can pass the gradebook item title via a url parameter to have the title auto-populated when the "Add a gradebook item" helper pops up. It would be nice to pass an optional due date, as well, so that the due date is auto-populated. This would not be populated if the helper is being used to edit an existing gradebook item.