Sadly I don't mean "complete things accidentally" in the sense of "whoops, I've just finished that 10,000 word essay... I didn't mean to do that until next week..."
No, I just mean your tasks in tedium. Every now and then I click on the wrong "Completed" button, and something that's still waiting to be done now has a line through it.
Until now the only way round it was to create a new task with the same contents as the one you've just incorrectly marked as done, which was a bit of a pain. Something a couple of users have reminded me about over the past week or two.
So we've added a little "Undo completed" button to each of the recently completed tasks. Rectifying an accidental completion is now just a click away.