It would be nice and desirable ,if Day's view of zk calendar can be customized so that we can add or create columns to create events or tasks along with the subtasks.
eg.
if we have activity "Board meeting" on a particular day,then we should be able to specify sub activities for this main activity i.e from 10.00 am to 11.30 am, say topic1 would be discussed,from 11.30 am to 12.30 pm topic2 would be discussed and so on.
So,bottomline is calendar is "incomplete" till we can't define day level activities.
So,I request you to add this imp. feature as soon as possible.

Regards.