I have submitted a naive fix for the lightbox issue.
That code should be part of the package Pier-Lightbox, not Pier-Seaside.
How does one normally get back from the lightbox? (As in back to the
structure that you came from).
Pressing the close button of the lightbox?
You still need to address the issue about validation errors being
non-resumable. They need to be raised, or modified to be resumable.
We need to get rid of those ugly exceptions all-together.