dmitriid: Edit: After this was posted, Ilya K pointed out that this is not a functionality provided by Apple. It’s a behaviour enabled by an extension, and it baheaves as well as it can given the constraints.

nikitonsky: Which window is active? Yep – the one on the right. You can tell by red traffic light

Beehives in the Muniellos Nature Reserve, Asturias province, Spain (© ABB Photo/Shutterstock)

This specification updates the iCalendar RELATED-TO property defined in RFC 5545 by adding new relation types and introduces new iCalendar