OK, I tested that with your tests and checked it against the spec. Looks fine according to my (admittedly lame) understanding of CLIM, and works on my (admittedly lame) single test on Allegro CL 7.0. Committed it.
I also added a docstring to MAKE-SCALING-TRANSFORMATION. I'm inclined to favor having these added, although not enough to say that people ought to slave to put them in everywhere. But I tend to add them to the code when I'm modding it for some other reasons. How do others feel about this? Is it a Bad Thing (do you prefer to have skinnier binaries at the expense of not having docstrings)?
R