Add a task with its subtasks to the calendar

I like to see an option where I can drag a task with all of it's subtasks to the calendar.

If the idea of subtasks is to break down a bigger task into smaller digestable chunks, then this approach makes it easier to go through the subtasks during a longer, focused session (that will be the main task).

An example – Lets say I have the task "E-mail". To that task I add a couple of e-mails that I need to send or respond to. When I add the Email-task, all the emails that I need to go through are also added "inside" the main task in the calendar.