ok - now I see / #3100

we have some more user-rights for users. Cause we're working together, everybody is allowed to "see anything", concerning people/projects/tasks/...

I think, that's the problem here. A user (no admin) who is allowed to "see anything", is allowed to see the private taks, but cannot open it. In that case, the user shouldn't see private tasks, he is not related to at all.