Editing 'Show only busy' task always changes summary to 'busy'

[raimund-schluessler]

I am actually not sure, whether this is a server issue, if we should handle this in the CalDAV apps or if this is a non-issue. Originally reported in #412 (comment). Input is very welcome.

Steps to reproduce

1. Share a calendar with write privileges to user B.
2. Create a task in said calendar and set the privacy setting to show only busy.
3. User B edits the task.

Actual behaviour

The edits are saved (as one would expect?), but the title is set to Busy if nothing else is put there.

Expected behaviour

Actually not really sure, what should happen. User B has write privileges to the calendar, so I guess it is ok, that he can change tasks. But for a show only busy task he doesnt get any more information than the title Busy, so changing any property potentially overwrites values without him knowing, as it happens for the title for example.

Tasks version:
v0.11.0 (as this supports sharing only), but happens before if you share via Calendar app.

Since the same thing happens in the Calendar app, I would like to hear what @nextcloud/calendar thinks about this. Potentially also @nextcloud/designers has an opinion.

[rkaraba]

Maybe show only busy should work only for read only Task lists (calendars) and it should be ignored in editable Task lists (calendars).
If shared Task list (calendar) is editable then act like show only busy = show full event
I think for most people there in no reason to use show only busy in editable Task lists (calendars) but someone can set it by mistake

[raimund-schluessler]

So, this is a server issue nextcloud/server#5551 in the first place, but we should forbid editing Show only busy tasks that are shared with you from the client side as well.

[raimund-schluessler]

We also have to prevent setting the access class to something else than PUBLIC if you are not owner of the calendar, is this correct @georgehrke ?

[georgehrke]

@raimund-schluessler Yes, ref nextcloud/calendar#657