[Gimp-user] liquid rescale to fill transparent areas

[Gary Aitken <gimp dreamchaser org>]

Can someone tell me how to get the liquid rescale plugin to expand
into transparent areas?  I have a panorama with stepped transparent
areas of sky in one part of the image.  I would like to expand the
sky into the transparent areas, but I can't get it to work.  The
image as a whole does not need to be resized.

I started by painting a preserve mask over everything but sky,
but the result looks like nothing was done.
I then tried using a rigidity mask and no preserve mask, with the
same result.

Is it even possible to use LqR to do this?  Is there a better way?

Thanks for any insights,

Gary