improve popup use when "submit level" validation occurs in the popup

Follwing jira http://jira.springframework.org/browse/SWF-1008, I would like to have this improvement to the popup.

When I display a popup and execute validation on the fields in it (submit level validation precisely), I would like the popup
to redisplay itself correctly when I display errors.

At the moment, we need to precise the processIds attribute that needs to point at the popup container in the tree so that things happen as
expected.

This requires a quite good understanding of webflow in order to make things happen as expected.

The fact is that when there is an error in a popup, we should not have to specify the region to be redraw. The popup function should know
that it only needs to redraw the popup. This, I think should be managed by the framework. As of now, it is not very intuitive.

If this improvement is too complicated in the short term, could it be possible to add a thorough example to the reference guide and reference application
so that newbies can at least copy the functionality and make it work ?