As a GH user, I want to work with a tree view of my epics within the planning board

We are drowning in tasks, and collecting them into some sort of hierarchy would be one way of managing them. Epics seem like the natural way to create a hierarchy, but they're not visible enough in the planning board.

What I would like is to view a tree hierarchy of my epics which I can expand and collapse - e.g.

[-] Do funky stuff
..[-] Funky feature 1
....[-] funk task
....[-] funk task 2
..[-] Funky feature 2
....[-] funk task A
[-] Do boring stuff
..[-] Boring feature 1
....[-] Boring task
..[-] Boring task 2
..[-] Boring feature 3
....[-] F3 part 1
......[-] Boring stuff
......[-] More boring stuff
....[-] Tedious stuff

I want to be able to expand and collapse the epics so I can control whether I view their sub-tasks.
I want to be able to drag and drop tasks/epics/... onto epics to make them children of the drop target.
I want to be able to rank epics against other epics at the same level of hierarchy.

However, I want to manage epics which span multiple iterations, and are in parallel with other epics which also span multiple iterations...

Not sure how epics should be ranked when sub-issues are ranked interleaved with each other - maybe the parent should be ranked before the first child at all times. If a child gets dragged earlier, the epic moves with it.

Having the epic tree view to give coarse ranking will speed up the prioritisation process, and being able to collapse epics will speed up bringing new tasks to the top of the priority when there is a long list of tasks.

This reproduces functionality which I would get if I used Rally or VersionOne.

[We're still on 4.3 because we our JIRA has dependencies on Plugins which don't yet support JIRA 4.1, so the sysadmins won't upgrade JIRA, so we can't upgrade Greenhopper, but I can't see anything in the Greenhopper list or documentation which suggests this has been implemented in 5.x]

Cheers,

Ian