Google launched add-ons this year, which are third-party apps that users can install for extra functionality and features. The developers of the add-ons are now creating installable App Script triggers for their add-ons, making it possible to respond to more user actions. Recent add-ons that now have installable triggers include Yet Another Mail Merge and YAMM.
We can expect to see this update in the UMICH domain in the coming weeks. For more information on Installable Triggers, see Installable triggers in add-ons for Google Docs and Sheets.