@gangwang After you finish editing a calendar and click the “OK” button, the calendar dialog displays again in view mode. When you have only one calendar, this makes it appear nothing happened after you click the OK button. When you have more than one calendar, the calendar dialog in view mode will display time slots for all calendars in different colors, so that the user gets a glimpse of the overall picture.
Thanks for bringing this to our attention. We’ll work on making this more intuitive.