p.s., Re: 2 displays for one cross section (different GriddedSets)

I wrote:

> You should have a DataReference to sliceFF that's been
> linked via an addReference() call to your DisplayImplJ2D.
> When you update the FlatField in sliceFF via a setData()
> call on the DataReference, that will trigger the
> DisplayImplJ2D to re-display.

A call to FlatField.setSamples() will also trigger the
DisplayImplJ2D to re-display.

Cheers, Bill