Is the calendar read-only?

I'm sorry for long delay to answer question. Been away. Is the calendar read-only? No! If it were, it wouldn't be possible to create any events, would it?

Messing around with Calendar, I realized where the error message comes from: If I copy an event that is on a calendar and try to paste it onto the task 'calendar', the error message is the result. So that's one piece of the puzzle solved: You can't paste calendar events into the task 'calendar', but you can paste them into a event calendar. To do so, you must click on the destination calendar in the list so that the item is highlighted.

That is, you can paste them, but sometimes the result is truly bizarre:

I have an event on Monday, Mar 2. If I copy it and paste it into Mar 3, it gets pasted into Mar 2. Ok, I thought, so pasting into a different day doesn't change the date automatically. I can deal with that. BUT--if you paste into Mar 10, say, I get 7 days of repeating event with the time set to 12 hours ahead of the original time, plus, -thhis is amazing- one event 25 hours ahead.

Now, I can't reproduce any of this strange behavior in an empty month. I am enclosing a true example of a screen shot of a busy month of March, with the two examples in green. (Copying a red calendar event and pasting with the green calendar highlighted) The green '12:05 PM FL' on Mar 2 resulted from a paste into Mar3. Pasting the original Mar 2 event into Mar 10 resulted in a) the green '12:05 AM Untitled' going for a week, and also the green '11:05 AM FL' on Mar 9!

Having spent some time testing all these scenarios, I'm getting familiar enough with Calendar to handle my needs, and don't actually need help. But the program truly needs some attention; these bugs may have far worse consequences.

To the maintainers, thanks for your time and effort past and future. I'm truly grateful to have a usable multi-platform calendar.