I use my Google Calendar for my homework schedule, as most of my professors use Google Calendar and you can click a button to have their events integrate with your calendar.
If I finish an event (homework assignment, studying for test, etc), I want to be able to make it grey-ish, kinda like this:
I would prefer to do this without deleting it (from my calendar, I have no control over the professor's calendar) would also work.
I thought about using:
Then going to More details. However, that only shows: