When two or more users (owner of the domain and invited developers) open the same file, a real time collaboration feature is automatically enabled. You will see the icon in the top right corner blinking. Click on the icon to open a collaboration log and a real time text chat. Each user has a colored square which indicates the collaboration color, as well as a cursor in the editor with the identical color (see images below):
Files in a collaboration mode are saved automatically. Users are notified when someone opens or closes a collaborative file.
By default all collaborators and a domain owner are given identical rights. When a collaborator attempts to delete a file, he’s prompted to notify the user(s) currently viewing this file:
All collaborators will immediately receive a request to close the file. Once such a file is closed, a user who has initiated deletion of the file, is free to delete it.
Here’s a short video demonstrating real time collaboration in Codenvy.