Comment 2 for bug 1210540

When user tries to delete an assigned security group, the Nova function in charge of destroying it, throws an exception with the message: "Security group is still in use" (see destroy function in nova/nova/compute/api.py). Also, the code is prepared to manage its translations.
We could add that message to the current one ("Unable to delete: group_name") when the exception is caught and the UI message is printed. The only thing to consider is that the method is general and it manages several exceptions, then we would print all the exception messages (see handle function in horizon/horizon/tables/actions.py). Is that ok?