Hello
If you try to view an Open Event in an Open Group, and you are not a member of the group, you get the following error: "You have to be a member of the group to view this event."
All the content of an Open Group is visible to non-members, I think events in group should as well. But maybe the user should not be able to attend (in my case it would be OK if he can, but I'm thinking of other ES customers who may think he should not

).
Regards
.Fixed in ES 1.4.1