select a key in the crypto control area (you might want to let the browser remember your choice)
the log area shows the data, which is sent to the server
open a second browser window (shortcut) and see the magic of collaboration (be careful to select the very same key in the crypto control area)
please bear in mind that this is proof of concept
also bear in mind that there is only one document for all of you. So if you pic another key, it might not work. In case there are issues you can always try to reset the document here: and then reload every participating browser window.