It is now much easier to join an existing co-editing session when a file is already being edited by a user in an application that allows co-editing: Microsoft Office Online or Google Workspace.
On folder listing, instead of the "lock" icon, a special "collaboration" icon is shown in this case:
When a user hovers over the file, a big blue "Co-Edit" button shows up:
Upon clicking the "Co-edit" button, a new tab will be opened, and it will be possible to co-edit the file - together with the user who started co-editing the document earlier.
The same "Co-Edit" button is shown in File Preview:
Desktop App, Mobile App, etc.
In Desktop App, the file will be "locked" - except for the case when the file is being opened by the same user who had started editing the file in Microsoft Office Online or Google Workspace (v3 integration) earlier.
Note. Legacy Google integrations - old, deprecated Google Docs and the domain-wide Google Drive integrations - are not supported and their means of collaboration remains unchanged.