I can't think of any appropriate roles for this sort of thing, and I don't see them coming along until the specs start dealing with web-based image editors more. Roles for dragging and dropping have been removed from aria 1.0, and the only other roles that might work would be very generic, like region. I'm not entirely certain I would use any roles. I would have probably toggle buttons representing the 4 edges/corners: toggle-on meaning arrows move things, toggle-off means they don't, and to hijack arrows, an application role might be needed. The whole image cropping thing could be an application role but then you'd have to be really careful with text anywhere as you're removing navigation abilities from SRs.