I'm trying to make a modal popup that allows keyboard navigation. I've looked at and tried using the code in calendar/amd/src/calendar.js, lib/amd/src/addblockmodal.js, and output/popup/amd/src/message_popover_controller.js.
I've been able to add a working modal popup, however, it does not work with keyboard navigation. I've looked into using CustomEvents to add keyboard navigation. How do I use the CustomEvents library? I noticed that calendar.js does not use CustomEvents.events.activate, but I am able to use keyboard navigation to open the modal window (the functionality I want for my modal popup).