Do we dare ask for the option of adding or omitting quizzes from the calendar with some sort of button or window that asks "add to calendar?" maybe in the set-up field?
For our moodles which are mostly quizzes (the math ones), many of the practice quizzes will be open for a long time, and they don't need to be listed on the calendar, but there may be other times when one would want a quiz/test listed.
--Mary