Moodle 3.8 and newer changed the implementation of the Participants page whose JavaScript was being duped into serving our purposes for bulk messaging and notes, and which also operated the "select all/none" buttons. My intent is to keep using Moodle's core functionality for messages and notes where feasible to avoid the maintenance burden that comes with cloning it, and adapt the select all/none feature to make use of the core-provided checkbox toggle group feature.