If you’re publishing a skuid event, just use some inline javascript to subscribe to that event.

Alternatively, you could think about using a model action on the calendar’s source model that looks for changes on the start datetime or room fields?

If you’re using javascript, you can build your popup in js, too: https://community.skuid.com/t/trigger-popup-from-javascript

Alterntively, you can use mBlazonry’s template component to listen for your event and use the action framework to build the popup. See https://community.skuid.com/t/template-component-with-action-framework and https://community.skuid.com/t/another-use-for-mb-template-w-action-framework-call-action-…