I have one calendar item “Appointments” which gets crowded out by the many other items present making it very awkward to view and find only appointments easily. If we could Select None and then choose one (in my case “Appointments”) the Calendar immediately becomes much more powerful and useful. I already have 10 different Calendar items on my Calendar and can imagine there may eventually be 10 more. It is prohibitively cumbersome to uncheck all but one just to view that one. It is also cumbersome to recheck All of the Calendar items, thus the need for a “Select All” option as well.