Hi Matt,
Thanks for posting, and for your interest in our plugins. We don’t have a tabbed sidebar calendar like you described, but our widgets may still suit your needs. Events Calendar PRO has a Mini Calendar Widget which shows a specified number of events in a list below. You can limit the calendar to one category of events (ex. Downtown Events). So you could potentially do two calendars for your different categories, or you might be able to customize the widget to work with tabs like your current one.
You can read more about our widgets and see screenshots here. The Advanced Upcoming Events List can also display a truncated list of events, from all categories or one specific one. Let me know if you have any further questions!
Best,
Leah