When mousing over the panes an outline of the old frame (with corners) is shown as if the frame wasn't diagonal at all. I would not be surprised if this is related to the hitbox issue. Since I'm not sure about that one way or another I'm reporting it as a separate issue =]

Yep, I should get around to implementing that...
I'll start poking around and probably release something soon.

The bounding boxes are linked to hitboxes, so I'll close this as a duplicate.

Duplicate of #4