When in the "Update Participants" mode for an event record, after selecting your participant query and field that you wish to update, it does not currently give you the option to "check all" or "uncheck all". Today's example of how it would be useful: I have 85 participants who we accidently marked as attended. I need to uncheck most of them as having NOT attended. To do that, I have to scroll through the entire list of 85 and uncheck each one. Annoying.